Spring与SpringBoot

1、Spring能做什么

1.1、Spring的能力

1.2、Spring的生态

https://spring.io/projects/spring-boot

覆盖了：

web开发

数据访问

安全控制

分布式

消息服务

移动开发

批处理

……

1.3、Spring5重大升级

1.3.1、响应式编程

1.3.2、内部源码设计

基于Java8的一些新特性，如：接口默认实现。重新设计源码架构。

2、为什么用SpringBoot

Spring Boot makes it easy to create stand-alone, production-grade Spring based Applications that you can “just run”.

能快速创建出生产级别的Spring应用

2.1、SpringBoot优点

• Create stand-alone Spring applications
• • 创建独立Spring应用
• Embed Tomcat, Jetty or Undertow directly (no need to deploy WAR files)
• • 内嵌web服务器
• Provide opinionated ‘starter’ dependencies to simplify your build configuration
• • 自动starter依赖，简化构建配置
• Automatically configure Spring and 3rd party libraries whenever possible
• • 自动配置Spring以及第三方功能
• Provide production-ready features such as metrics, health checks, and externalized configuration
• • 提供生产级别的监控、健康检查及外部化配置
• Absolutely no code generation and no requirement for XML configuration
• • 无代码生成、无需编写XML

SpringBoot是整合Spring技术栈的一站式框架

SpringBoot是简化Spring技术栈的快速开发脚手架

2.2、SpringBoot缺点

• 人称版本帝，迭代快，需要时刻关注变化
• 封装太深，内部原理复杂，不容易精通

3、时代背景

3.1、微服务

James Lewis and Martin Fowler (2014) 提出微服务完整概念。https://martinfowler.com/microservices/

In short, the microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. These services are built around business capabilities and independently deployable by fully automated deployment machinery. There is a bare minimum of centralized management of these services, which may be written in different programming languages and use different data storage technologies.— James Lewis and Martin Fowler (2014)

• 微服务是一种架构风格
• 一个应用拆分为一组小型服务
• 每个服务运行在自己的进程内，也就是可独立部署和升级
• 服务之间使用轻量级HTTP交互
• 服务围绕业务功能拆分
• 可以由全自动部署机制独立部署
• 去中心化，服务自治。服务可以使用不同的语言、不同的存储技术

3.2、分布式

分布式的困难

• 远程调用
• 服务发现
• 负载均衡
• 服务容错
• 配置管理
• 服务监控
• 链路追踪
• 日志管理
• 任务调度
• ……

分布式的解决

• SpringBoot + SpringCloud

3.3、云原生

原生应用如何上云。 Cloud Native

上云的困难

• 服务自愈
• 弹性伸缩
• 服务隔离
• 自动化部署
• 灰度发布
• 流量治理
• ……

上云的解决

4、如何学习SpringBoot

4.1、官网文档架构

查看版本新特性；

https://github.com/spring-projects/spring-boot/wiki#release-notes

SpringBoot2入门

1、系统要求

• Java 8 & 兼容java14 .
• Maven 3.3+
• idea 2019.1.2

1.1、maven设置

<mirrors>
      <mirror>
        <id>nexus-aliyun</id>
        <mirrorOf>central</mirrorOf>
        <name>Nexus aliyun</name>
        <url>http://maven.aliyun.com/nexus/content/groups/public</url>
      </mirror>
  </mirrors>
  <profiles>
         <profile>
              <id>jdk-1.8</id>
              <activation>
                <activeByDefault>true</activeByDefault>
                <jdk>1.8</jdk>
              </activation>
              <properties>
                <maven.compiler.source>1.8</maven.compiler.source>
                <maven.compiler.target>1.8</maven.compiler.target>
                <maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
              </properties>
         </profile>
  </profiles>

2、HelloWorld

需求：浏览发送/hello请求，响应 Hello，Spring Boot 2

2.1、创建maven工程

…

2.2、引入依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

2.3、创建主程序

/**
 * 主程序类
 * @SpringBootApplication：这是一个SpringBoot应用
 */
@SpringBootApplication
public class MainApplication {
    public static void main(String[] args) {
        SpringApplication.run(MainApplication.class,args);
    }
}

2.4、编写业务

@RestController
public class HelloController {
    @RequestMapping("/hello")
    public String handle01(){
        return "Hello, Spring Boot 2!";
    }
}

2.5、测试

直接运行main方法

2.6、简化配置

application.properties

server.port=8888

2.7、简化部署

 <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

把项目打成jar包，直接在目标服务器执行即可。

注意点：

• 取消掉cmd的快速编辑模式

自动配置原理

1、SpringBoot特点

1.1、依赖管理

• 父项目做依赖管理

依赖管理    
<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>
</parent>
他的父项目
 <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-dependencies</artifactId>
    <version>2.3.4.RELEASE</version>
  </parent>
几乎声明了所有开发中常用的依赖的版本号,自动版本仲裁机制

• 开发导入starter场景启动器
  1、见到很多 spring-boot-starter- ： 就某种场景
  2、只要引入starter，这个场景的所有常规需要的依赖我们都自动引入
  3、SpringBoot所有支持的场景
  https://docs.spring.io/spring-boot/docs/current/reference/html/using-spring-boot.html#using-boot-starter
  4、见到的 -spring-boot-starter： 第三方为我们提供的简化开发的场景启动器。
  5、*所有场景启动器最底层的依赖org.springframework.boot

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter</artifactId>
  <version>2.3.4.RELEASE</version>
  <scope>compile</scope>
</dependency>

场景依赖例图：

• 无需关注版本号，自动版本仲裁
  1、引入依赖默认都可以不写版本
  2、引入非版本仲裁的jar，要写版本号
• 可以修改默认版本号
  1、查看spring-boot-dependencies里面规定当前依赖的版本 用的 key。
  2、在当前项目里面重写配置

<properties>
    <mysql.version>5.1.43</mysql.version>
</properties>

1.2、自动配置

• 自动配好Tomcat
• • 引入Tomcat依赖。
  • 配置Tomcat

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
      <version>2.3.4.RELEASE</version>
      <scope>compile</scope>
    </dependency>

• 自动配好SpringMVC
• • 引入SpringMVC全套组件
  • 自动配好SpringMVC常用组件（功能）
• 自动配好Web常见功能，如：字符编码问题
• • SpringBoot帮我们配置好了所有web开发的常见场景
• 默认的包结构
• • 主程序所在包及其下面的所有子包里面的组件都会被默认扫描进来
  • 无需以前的包扫描配置
• • 想要改变扫描路径
    • @SpringBootApplication(scanBasePackages=“com.atguigu”)
• • • 或者@ComponentScan 指定扫描路径

@SpringBootApplication
等同于
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan("com.atguigu.boot")

• 各种配置拥有默认值
• • 默认配置最终都是映射到某个类上，如：MultipartProperties
  • 配置文件的值最终会绑定每个类上，这个类会在容器中创建对象
• 按需加载所有自动配置项
• • 非常多的starter
  • 引入了哪些场景这个场景的自动配置才会开启
• • SpringBoot所有的自动配置功能都在 spring-boot-autoconfigure 包里面
• ……

2、容器功能

2.1、组件添加

1、@Configuration

• 基本使用
• Full模式与Lite模式
• • 示例
  • 最佳实战
• • 配置 类组件之间无依赖关系用Lite模式加速容器启动过程，减少判断
  • 配置类组件之间有依赖关系，方法会被调用得到之前单实例组件，用Full模式
  • bean类：
  • ```java package boot.bean;

public class User { private String userName; private int age; private Pet pet;

public User() {
}
public User(String userName, int age, Pet pet) {
    this.userName = userName;
    this.age = age;
    this.pet = pet;
}
public Pet getPet() {
    return pet;
}
public void setPet(Pet pet) {
    this.pet = pet;
}
public String getUserName() {
    return userName;
}
public void setUserName(String userName) {
    this.userName = userName;
}
public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}
@Override
public String toString() {
    return "User{" +
            "userName='" + userName + '\'' +
            ", age=" + age +
            ", pet=" + pet +
            '}';
}

}

   -   
```java
package boot.bean;
public class Pet {
    private String petName;
    public Pet(String petName) {
        this.petName = petName;
    }
    public Pet() {
    }
    public String getPetName() {
        return petName;
    }
    public void setPetName(String petName) {
        this.petName = petName;
    }
    @Override
    public String toString() {
        return "Pet{" +
                "petName='" + petName + '\'' +
                '}';
    }
}

• 配置实例:

• ```java Configuration使用示例 /**

  • 1、配置类里面使用@Bean标注在方法上给容器注册组件，默认也是单实例的
  • 2、配置类本身也是组件
  • 3、proxyBeanMethods：代理bean的方法
  • Full(proxyBeanMethods = true)、【保证每个@Bean方法被调用多少次返回的组件都是单实例的】
  • Lite(proxyBeanMethods = false)【每个@Bean方法被调用多少次返回的组件都是新创建的】
  • 组件依赖必须使用Full模式默认。其他默认是否Lite模式 / @Configuration(proxyBeanMethods = false) //告诉SpringBoot这是一个配置类 == 配置文件 public class MyConfig {

  /**

  • Full:外部无论对配置类中的这个组件注册方法调用多少次获取的都是之前注册容器中的单实例对象
  • @return */ @Bean //给容器中添加组件。以方法名作为组件的id。返回类型就是组件类型。返回的值，就是组件在容器中的实例 public User user01(){ User zhangsan = new User(“zhangsan”, 18); //user组件依赖了Pet组件 zhangsan.setPet(tomcatPet()); return zhangsan; }

  @Bean(“tom”)//定义个组件的id，而不是方法名 public Pet tomcatPet(){ return new Pet(“tomcat”); } }

  ##########################@Configuration测试代码如下

  @SpringBootApplication public class MainApplication {

  public static void main(String[] args) { //1、返回我们IOC容器 ConfigurableApplicationContext run = SpringApplication.run(MainApplication.class, args);

  //2、查看容器里面的组件 String[] names = run.getBeanDefinitionNames(); for (String name : names) {

   System.out.println(name);

  }

  //3、从容器中获取组件

  Pet tom01 = run.getBean(“tom”, Pet.class);

  Pet tom02 = run.getBean(“tom”, Pet.class);

  System.out.println(“组件：”+(tom01 == tom02));

    //4、com.atguigu.boot.config.MyConfig$$EnhancerBySpringCGLIB$$51f1e1ca@1654a892
    MyConfig bean = run.getBean(MyConfig.class);
    System.out.println(bean);
    //如果@Configuration(proxyBeanMethods = true)代理对象调用方法。SpringBoot总会检查这个组件是否在容器中有。
    //保持组件单实例
    User user = bean.user01();
    User user1 = bean.user01();
    System.out.println(user == user1);
    User user01 = run.getBean("user01", User.class);
    Pet tom = run.getBean("tom", Pet.class);
    System.out.println("用户的宠物："+(user01.getPet() == tom));
}

}

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#### 2、@Bean、@Component、@Controller、@Service、[@Repository ](/Repository ) 
- spring已经讲过
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#### 3、@ComponentScan、[@Import ](/Import ) 
-  import用法: <br />验证注入的组件: <br />结果可知：boot.bean.User，newUser import创建的是全类名的组件 
```java
 /*
 *    @Import({User.class, DBHelper.class})
 *      给容器中自动创建出这两个类型的组件、默认组件的名字就是全类名
 */
@Import({User.class, DBHelper.class})
@Configuration(proxyBeanMethods = false) //告诉SpringBoot这是一个配置类 == 配置文件
public class MyConfig {
}

//获取import导入组件的bean
String[] users = run.getBeanNamesForType(User.class);
for (String s : users) {
    System.out.println(s);
}

4、@Conditional

• 条件装配：满足Conditional指定的条件，则进行组件注入

=====================测试条件装配==========================
@Configuration(proxyBeanMethods = false) //告诉SpringBoot这是一个配置类 == 配置文件
//@ConditionalOnBean(name = "tom")
@ConditionalOnMissingBean(name = "tom")
public class MyConfig {
    /**
     * Full:外部无论对配置类中的这个组件注册方法调用多少次获取的都是之前注册容器中的单实例对象
     * @return
     */
    @Bean //给容器中添加组件。以方法名作为组件的id。返回类型就是组件类型。返回的值，就是组件在容器中的实例
   // @ConditionalOnMissingBean(name="tom")
    public User user01(){
        User zhangsan = new User("zhangsan", 18);
        //user组件依赖了Pet组件
        zhangsan.setPet(tomcatPet());
        return zhangsan;
    }
    @Bean("tom22")
    public Pet tomcatPet(){
        return new Pet("tomcat");
    }
}
public static void main(String[] args) {
        //1、返回我们IOC容器
        ConfigurableApplicationContext run = SpringApplication.run(MainApplication.class, args);
        //2、查看容器里面的组件
        String[] names = run.getBeanDefinitionNames();
        for (String name : names) {
            System.out.println(name);
        }
        boolean tom = run.containsBean("tom");
        System.out.println("容器中Tom组件："+tom);
        boolean user01 = run.containsBean("user01");
        System.out.println("容器中user01组件："+user01);
        boolean tom22 = run.containsBean("tom22");
        System.out.println("容器中tom22组件："+tom22);
    }

2.2、原生配置文件引入

@ImportResource

• 可以引入配置文件，将配置文件组件自动注入IOC

  ======================beans.xml=========================
  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:context="http://www.springframework.org/schema/context"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
   <bean id="haha" class="com.atguigu.boot.bean.User">
       <property name="name" value="zhangsan"></property>
       <property name="age" value="18"></property>
   </bean>
   <bean id="hehe" class="com.atguigu.boot.bean.Pet">
       <property name="name" value="tomcat"></property>
   </bean>
  </beans>

  ```java @ImportResource(“classpath:beans.xml”) public class MyConfig {}

======================测试================= boolean haha = run.containsBean(“haha”); boolean hehe = run.containsBean(“hehe”); System.out.println(“haha：”+haha);//true System.out.println(“hehe：”+hehe);//true

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#### 2.3、配置绑定
-  如何使用Java读取到properties文件中的内容，并且把它封装到JavaBean中，以供随时使用；  
```java
public class getProperties {
     public static void main(String[] args) throws FileNotFoundException, IOException {
         Properties pps = new Properties();
         pps.load(new FileInputStream("a.properties"));
         Enumeration enum1 = pps.propertyNames();//得到配置文件的名字
         while(enum1.hasMoreElements()) {
             String strKey = (String) enum1.nextElement();
             String strValue = pps.getProperty(strKey);
             System.out.println(strKey + "=" + strValue);
             //封装到JavaBean。
         }
     }
 }

springboot提供更简洁的注解方式

• @ConfigurationProperties使用(@Component + @ConfigurationProperties)

  • 配置文件:

    mycar.brand=BMW
    mycar.price=1000000

  • Car类：
    ```java package boot.bean;

import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.stereotype.Component;

/**

• 只有在容器中的组件，才会拥有SpringBoot提供的强大功能 */ @Component @ConfigurationProperties(prefix = “mycar”) public class Car { private String brand; public Integer price;

  public Car(String brand, Integer price) {

   this.brand = brand;
   this.price = price;

  }

  public Car() { }

  public String getBrand() {

   return brand;

  }

  public void setBrand(String brand) {

   this.brand = brand;

  }

  public Integer getPrice() {

   return price;

  }

  public void setPrice(Integer price) {

   this.price = price;

  }

  @Override public String toString() {

   return "Car{" +
           "brand='" + brand + '\'' +
           ", price=" + price +
           '}';

  } }

  -  在控制器类中可以自动获取  
  ```java
  @RestController
  public class FirstController {
   @Autowired
   Car car;
   @RequestMapping("/car")
   public Car car(){
       return car;
   }
  }

• @ConfigurationProperties使用(@EnableConfigurationProperties + @ConfigurationProperties)
  • 需要在配置类加入注解(在为第三方包的对象，无法使用@Component时可以使用)

    @EnableConfigurationProperties(Car.class)
    public class MyConfig {

3、自动配置原理入门

3.1、引导加载自动配置类

@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
        @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication{}
======================

1、@SpringBootConfiguration

@Configuration。代表当前是一个配置类

2、@ComponentScan

指定扫描哪些，Spring注解；

3、@EnableAutoConfiguration

@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {}

1、@AutoConfigurationPackage

自动配置包？指定了默认的包规则

@Import(AutoConfigurationPackages.Registrar.class)  //给容器中导入一个组件
public @interface AutoConfigurationPackage {}
//利用Registrar给容器中导入一系列组件
//将指定的一个包下的所有组件导入进来？MainApplication 所在包下。

2、@Import(AutoConfigurationImportSelector.class)

1、利用getAutoConfigurationEntry(annotationMetadata);给容器中批量导入一些组件
2、调用List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes)获取到所有需要导入到容器中的配置类
3、利用工厂加载 Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader)；得到所有的组件
4、从META-INF/spring.factories位置来加载一个文件。
    默认扫描我们当前系统里面所有META-INF/spring.factories位置的文件
    spring-boot-autoconfigure-2.3.4.RELEASE.jar包里面也有META-INF/spring.factories

文件里面写死了spring-boot一启动就要给容器中加载的所有配置类
spring-boot-autoconfigure-2.3.4.RELEASE.jar/META-INF/spring.factories
# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration,\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.solr.SolrRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.rsocket.RSocketSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration

3.2、按需开启自动配置项

• 虽然我们127个场景的所有自动配置启动的时候默认全部加载。xxxxAutoConfiguration
  按照条件装配规则（@Conditional），最终会按需配置。

3.3、修改默认配置

• 解析web一些配置:

@Configuration(
    proxyBeanMethods = false
)
@Conditional({DispatcherServletAutoConfiguration.DefaultDispatcherServletCondition.class})
//包含此类的组件则实行下面的方法
@ConditionalOnClass({ServletRegistration.class})
//1.将配置文件与组件绑定2.在注入到配置文件
@EnableConfigurationProperties({WebMvcProperties.class})
protected static class DispatcherServletConfiguration {
    protected DispatcherServletConfiguration() {
    }
    @Bean(
        name = {"dispatcherServlet"}
    )
    //不用在手动的配置DispatcherServlet，springboot会new一个,并返回
    public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties) {
        DispatcherServlet dispatcherServlet = new DispatcherServlet();
        dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());
        dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());
        dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());
        dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());
        dispatcherServlet.setEnableLoggingRequestDetails(webMvcProperties.isLogRequestDetails());
        return dispatcherServlet;
    }

        @Bean
        @ConditionalOnBean(MultipartResolver.class)  //容器中有这个类型组件
        @ConditionalOnMissingBean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME) //容器中没有这个名字 multipartResolver 的组件,SpringBoot会才会自动配置，如果自己@Bean一个multipartResolver组件，就不会配置
        public MultipartResolver multipartResolver(MultipartResolver resolver) {
            //给@Bean标注的方法传入了对象参数，这个参数的值就会从容器中找。
            //SpringMVC multipartResolver。防止有些用户配置的文件上传解析器不符合规范
            // Detect if the user has created a MultipartResolver but named it incorrectly
            return resolver;
        }
给容器中加入了文件上传解析器；

• SpringBoot默认会在底层配好所有的组件。但是如果用户自己配置了以用户的优先

@Bean
//不包含CharacterEncodingFilter会执行方法,自动创建
@ConditionalOnMissingBean
public CharacterEncodingFilter characterEncodingFilter() {
    CharacterEncodingFilter filter = new OrderedCharacterEncodingFilter();
    filter.setEncoding(this.properties.getCharset().name());
    filter.setForceRequestEncoding(this.properties.shouldForce(org.springframework.boot.web.servlet.server.Encoding.Type.REQUEST));
    filter.setForceResponseEncoding(this.properties.shouldForce(org.springframework.boot.web.servlet.server.Encoding.Type.RESPONSE));
    return filter;
}

@Bean
    @ConditionalOnMissingBean
    public CharacterEncodingFilter characterEncodingFilter() {
    }

总结：

• SpringBoot先加载所有的自动配置类 xxxxxAutoConfiguration
• 每个自动配置类按照条件进行生效，默认都会绑定配置文件指定的值。xxxxProperties里面拿。xxxProperties和配置文件进行了绑定
• 生效的配置类就会给容器中装配很多组件
• 只要容器中有这些组件，相当于这些功能就有了
• 定制化配置
• • 用户直接自己@Bean替换底层的组件
  • 用户去看这个组件是获取的配置文件什么值就去修改。

xxxxxAutoConfiguration —-> 组件 —-> xxxxProperties里面拿值 ——> application.properties

3.4、最佳实践

• 引入场景依赖
• • https://docs.spring.io/spring-boot/docs/current/reference/html/using-spring-boot.html#using-boot-starter
• 查看自动配置了哪些（选做）
• • 自己分析，引入场景对应的自动配置一般都生效了
  • 配置文件中debug=true开启自动配置报告。Negative（不生效）\Positive（生效）
• 是否需要修改
• • 参照文档修改配置项
• • • https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-application-properties.html#common-application-properties
    • 自己分析。xxxxProperties绑定了配置文件的哪些。
• • 自定义加入或者替换组件
• • • @Bean、@Component。。。
• • 自定义器 XXXXXCustomizer；
  • ……

4、开发小技巧

4.1、Lombok

• 简化JavaBean开发
  idea中搜索安装lombok插件

   <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
   </dependency>

  ```java ===============================简化JavaBean开发=================================== @NoArgsConstructor //@AllArgsConstructor @Data @ToString @EqualsAndHashCode public class User {

  private String name; private Integer age;

  private Pet pet;

  public User(String name,Integer age){

   this.name = name;
   this.age = age;

  }

}

================================简化日志开发=================================== @Slf4j @RestController public class HelloController { @RequestMapping(“/hello”) public String handle01(@RequestParam(“name”) String name){

    log.info("请求进来了....");
    return "Hello, Spring Boot 2!"+"你好："+name;
}

}

<a name="1c2f70d9"></a>
### 4.2、dev-tools
```xml
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

项目或者页面修改以后：Ctrl+F9；

4.3、Spring Initailizr（项目初始化向导）

0、选择我们需要的开发场景

1、自动依赖引入

2、自动创建项目结构

3、自动编写好主配置类

配置文件

1、文件类型

1.1、properties

同以前的properties用法

1.2、yaml

1.2.1、简介

YAML 是 “YAML Ain’t Markup Language”（YAML 不是一种标记语言）的递归缩写。在开发的这种语言时，YAML 的意思其实是：”Yet Another Markup Language”（仍是一种标记语言）。

非常适合用来做以数据为中心的配置文件

1.2.2、基本语法

• key: value；kv之间有空格
• 大小写敏感
• 使用缩进表示层级关系
• 缩进不允许使用tab，只允许空格
• 缩进的空格数不重要，只要相同层级的元素左对齐即可
• ‘#’表示注释
• 字符串无需加引号，如果要加，’’与””表示字符串内容 会被 转义/不转义

1.2.3、数据类型

• 字面量：单个的、不可再分的值。date、boolean、string、number、null

k: v

• 对象：键值对的集合。map、hash、set、object

行内写法：  k: {k1:v1,k2:v2,k3:v3}
#或
k: 
    k1: v1
  k2: v2
  k3: v3

• 数组：一组按次序排列的值。array、list、queue

行内写法：  k: [v1,v2,v3]
#或者
k:
 - v1
 - v2
 - v3

1.2.4、示例

@Data
public class Person {
    private String userName;
    private Boolean boss;
    private Date birth;
    private Integer age;
    private Pet pet;
    private String[] interests;
    private List<String> animal;
    private Map<String, Object> score;
    private Set<Double> salarys;
    private Map<String, List<Pet>> allPets;
}
@Data
public class Pet {
    private String name;
    private Double weight;
}

# yaml表示以上对象
person:
#单引号会将 \n 作为字符串输出 双引号会将\n作为换行输出
#双引号不会转义，单引号会转义
  userName: zhangsan
  boss: false
  birth: 2019/12/12 20:12:33
  age: 18
  pet: 
    name: tomcat
    weight: 23.4
  interests: [篮球,游泳]
  animal: 
    - jerry
    - mario
  score:
    english: 
      first: 30
      second: 40
      third: 50
    math: [131,140,148]
    chinese: {first: 128,second: 136}
  salarys: [3999,4999.98,5999.99]
  allPets:
    sick:
      - {name: tom}
      - {name: jerry,weight: 47}
    health: [{name: mario,weight: 47}]

注意：使用yml时报

导入依赖:（编写时有提示）

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>

2、配置提示

自定义的类和配置文件绑定一般没有提示。

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
 <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.springframework.boot</groupId>
                            <artifactId>spring-boot-configuration-processor</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

Web开发

1、SpringMVC自动配置概览

Spring Boot provides auto-configuration for Spring MVC that works well with most applications.(大多场景我们都无需自定义配置)

The auto-configuration adds the following features on top of Spring’s defaults:

• Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.
• • 内容协商视图解析器和BeanName视图解析器
• Support for serving static resources, including support for WebJars (covered later in this document)).
• • 静态资源（包括webjars）
• Automatic registration of Converter, GenericConverter, and Formatter beans.
• • 自动注册 Converter，GenericConverter，Formatter
• Support for HttpMessageConverters (covered later in this document).
• • 支持 HttpMessageConverters （后来我们配合内容协商理解原理）
• Automatic registration of MessageCodesResolver (covered later in this document).
• • 自动注册 MessageCodesResolver （国际化用）
• Static index.html support.
• • 静态index.html 页支持
• Custom Favicon support (covered later in this document).
• • 自定义 Favicon
• Automatic use of a ConfigurableWebBindingInitializer bean (covered later in this document).
• • 自动使用 ConfigurableWebBindingInitializer ，（DataBinder负责将请求数据绑定到JavaBean上）

If you want to keep those Spring Boot MVC customizations and make more MVC customizations (interceptors, formatters, view controllers, and other features), you can add your own @Configuration class of type WebMvcConfigurer but without @EnableWebMvc.

不用@EnableWebMvc注解。使用 **@Configuration** + **WebMvcConfigurer** 自定义规则

If you want to provide custom instances of RequestMappingHandlerMapping, RequestMappingHandlerAdapter, or ExceptionHandlerExceptionResolver, and still keep the Spring Boot MVC customizations, you can declare a bean of type WebMvcRegistrations and use it to provide custom instances of those components.

声明 **WebMvcRegistrations** 改变默认底层组件

If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with @EnableWebMvc, or alternatively add your own @Configuration-annotated DelegatingWebMvcConfiguration as described in the Javadoc of @EnableWebMvc.

使用 **@EnableWebMvc+@Configuration+DelegatingWebMvcConfiguration 全面接管SpringMVC**

2、简单功能分析

2.1、静态资源访问

1、静态资源目录

只要静态资源放在类路径下： called /static (or /public or /resources or /META-INF/resources

访问 ： 当前项目根路径/ + 静态资源名

原理： 静态映射/**。

请求进来，先去找Controller看能不能处理。不能处理的所有请求又都交给静态资源处理器。静态资源也找不到则响应404页面

改变默认的静态资源路径

spring:
  mvc:
    static-path-pattern: /res/**
  web:
    resources:
      static-locations: [classpath:/haha/]    //classpath后面没空格

2、静态资源访问前缀

默认无前缀

spring:
  mvc:
    static-path-pattern: /res/**

当前项目 + static-path-pattern + 静态资源名 = 静态资源文件夹下找

3、webjar

自动映射 /webjars/**

https://www.webjars.org/

        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.5.1</version>
        </dependency>

访问地址：http://localhost:8080/webjars/jquery/3.5.1/jquery.js 后面地址要按照依赖里面的包路径

2.2、欢迎页支持

• 静态资源路径下 index.html
• • 可以配置静态资源路径
  • 但是不可以配置静态资源的访问前缀。否则导致 index.html不能被默认访问

spring:
#  mvc:
#    static-path-pattern: /res/**   这个会导致welcome page功能失效
  resources:
    static-locations: [classpath:/haha/]

• controller能处理/index

2.3、自定义 Favicon

favicon.ico 放在静态资源目录下即可。

spring:
#  mvc:
#    static-path-pattern: /res/**   这个会导致 Favicon 功能失效

2.4、静态资源配置原理

• SpringBoot启动默认加载 xxxAutoConfiguration 类（自动配置类）
• SpringMVC功能的自动配置类 WebMvcAutoConfiguration，生效

@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
        ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {}

• 给容器中配了什么。

    @Configuration(proxyBeanMethods = false)
    @Import(EnableWebMvcConfiguration.class)
    @EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
    @Order(0)
    public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {}

• 配置文件的相关属性和xxx进行了绑定。WebMvcProperties==spring.mvc、ResourceProperties==spring.resources

1、配置类只有一个有参构造器

    //有参构造器所有参数的值都会从容器中确定
//ResourceProperties resourceProperties；获取和spring.resources绑定的所有的值的对象
//WebMvcProperties mvcProperties 获取和spring.mvc绑定的所有的值的对象
//ListableBeanFactory beanFactory Spring的beanFactory
//HttpMessageConverters 找到所有的HttpMessageConverters
//ResourceHandlerRegistrationCustomizer 找到 资源处理器的自定义器。=========
//DispatcherServletPath  
//ServletRegistrationBean   给应用注册Servlet、Filter....
    public WebMvcAutoConfigurationAdapter(ResourceProperties resourceProperties, WebMvcProperties mvcProperties,
                ListableBeanFactory beanFactory, ObjectProvider<HttpMessageConverters> messageConvertersProvider,
                ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
                ObjectProvider<DispatcherServletPath> dispatcherServletPath,
                ObjectProvider<ServletRegistrationBean<?>> servletRegistrations) {
            this.resourceProperties = resourceProperties;
            this.mvcProperties = mvcProperties;
            this.beanFactory = beanFactory;
            this.messageConvertersProvider = messageConvertersProvider;
            this.resourceHandlerRegistrationCustomizer = resourceHandlerRegistrationCustomizerProvider.getIfAvailable();
            this.dispatcherServletPath = dispatcherServletPath;
            this.servletRegistrations = servletRegistrations;
        }

2、资源处理的默认规则

@Override
        public void addResourceHandlers(ResourceHandlerRegistry registry) {
            if (!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
                return;
            }
            Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
            CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
            //webjars的规则
            if (!registry.hasMappingForPattern("/webjars/**")) {
                customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
                        .addResourceLocations("classpath:/META-INF/resources/webjars/")
                        .setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
            }
            //
            String staticPathPattern = this.mvcProperties.getStaticPathPattern();
            if (!registry.hasMappingForPattern(staticPathPattern)) {
                customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
                        .addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
                        .setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
            }
        }
spring:
#  mvc:
#    static-path-pattern: /res/**
  resources:
    add-mappings: false   禁用所有静态资源规则
@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties {
    private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
            "classpath:/resources/", "classpath:/static/", "classpath:/public/" };
    /**
     * Locations of static resources. Defaults to classpath:[/META-INF/resources/,
     * /resources/, /static/, /public/].
     */
    private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;

3、欢迎页的处理规则

    HandlerMapping：处理器映射。保存了每一个Handler能处理哪些请求。    
    @Bean
        public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
                FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
            WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
                    new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
                    this.mvcProperties.getStaticPathPattern());
            welcomePageHandlerMapping.setInterceptors(getInterceptors(mvcConversionService, mvcResourceUrlProvider));
            welcomePageHandlerMapping.setCorsConfigurations(getCorsConfigurations());
            return welcomePageHandlerMapping;
        }
    WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
            ApplicationContext applicationContext, Optional<Resource> welcomePage, String staticPathPattern) {
        if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
            //要用欢迎页功能，必须是/**
            logger.info("Adding welcome page: " + welcomePage.get());
            setRootViewName("forward:index.html");
        }
        else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
            // 调用Controller  /index
            logger.info("Adding welcome page template: index");
            setRootViewName("index");
        }
    }

4、favicon

• 浏览器会发送/favicon.ioc请求获取到图标，整个session期间不再获取

3、请求参数处理

请求映射

1、rest使用与原理

• @xxxMapping；
• Rest风格支持（使用HTTP请求方式动词来表示对资源的操作）
• • 以前：*/getUser 获取用户 /deleteUser 删除用户 /editUser 修改用户 /saveUser 保存用户
  • 现在： /user GET-获取用户 DELETE-删除用户 PUT-修改用户 POST-保存用户
• • 核心Filter；HiddenHttpMethodFilter
• • • 用法： 表单method=post，隐藏域 _method=put
    • SpringBoot中手动开启
• • 扩展：如何把_method 这个名字换成我们自己喜欢的。
  • 测试:

• ```java @RequestMapping(value = “/user”,method = RequestMethod.GET) public String getUser(){

  return "GET-张三";

  }

  @RequestMapping(value = “/user”,method = RequestMethod.POST) public String saveUser(){

  return "POST-张三";

  }

@RequestMapping(value = "/user",method = RequestMethod.PUT)
public String putUser(){
    return "PUT-张三";
}
@RequestMapping(value = "/user",method = RequestMethod.DELETE)
public String deleteUser(){
    return "DELETE-张三";
}
@Bean
@ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
@ConditionalOnProperty(prefix = "spring.mvc.hiddenmethod.filter", name = "enabled", matchIfMissing = false)
public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
    return new OrderedHiddenHttpMethodFilter();
}

//自定义filter @Bean public HiddenHttpMethodFilter hiddenHttpMethodFilter(){ HiddenHttpMethodFilter methodFilter = new HiddenHttpMethodFilter(); methodFilter.setMethodParam(“_m”); return methodFilter; }

-   
```html
测试REST风格；
<form action="/user" method="get">
    <input value="REST-GET 提交" type="submit"/>
</form>
<form action="/user" method="post">
    <input value="REST-POST 提交" type="submit"/>
</form>
<form action="/user" method="post">
    <input name="_method" type="hidden" value="delete"/>
    <input name="_m" type="hidden" value="delete"/>
    <input value="REST-DELETE 提交" type="submit"/>
</form>
<form action="/user" method="post">
    <input name="_method" type="hidden" value="PUT"/>
    <input value="REST-PUT 提交" type="submit"/>
</form>
<hr/>

• Rest原理（表单提交要使用REST的时候）

  • protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
    HttpServletRequest requestToUse = request;
    if ("POST".equals(request.getMethod()) && request.getAttribute("javax.servlet.error.exception") == null) {
     String paramValue = request.getParameter(this.methodParam);
     if (StringUtils.hasLength(paramValue)) {
         //会将请求都转化为大写，因此小写不影响
         String method = paramValue.toUpperCase(Locale.ENGLISH);
         if (ALLOWED_METHODS.contains(method)) {
             requestToUse = new HiddenHttpMethodFilter.HttpMethodRequestWrapper(request, method);
         }
     }
    }
     //将包装后的requesWrapper放行
     filterChain.doFilter((ServletRequest)requestToUse, response);
    }

  • 表单提交会带上_method=PUT

  • 请求过来被HiddenHttpMethodFilter拦截
  • • 请求是否正常，并且是POST
  • • • 获取到_method的值。
      • 兼容以下请求；PUT.DELETE.PATCH
  • • • 原生request（post），包装模式requesWrapper重写了getMethod方法，返回的是传入的值。
        ```java //是原生的selevet，并重写了getMethod private static class HttpMethodRequestWrapper extends HttpServletRequestWrapper { private final String method;

    public HttpMethodRequestWrapper(HttpServletRequest request, String method) { super(request); this.method = method; }

    public String getMethod() { return this.method; } }

       -  **过滤器链放行的时候用wrapper。以后的方法调用getMethod是调用requesWrapper的。** 
       -   
    ```yml
    spring:
    mvc:
    hiddenmethod:
    filter:
      enabled: true     #开启页面表单的Rest功能

• Rest使用客户端工具

  • 如PostMan直接发送Put、delete等方式请求，无需Filter。

• 如何把_method字段改成我们喜欢的

  • 自己注入一个组件

    @Configuration(proxyBeanMethods = false)
    public class WebConfig /*implements WebMvcConfigurer*/ {
    @Bean
    public HiddenHttpMethodFilter hiddenHttpMethodFilter(){
       HiddenHttpMethodFilter methodFilter = new HiddenHttpMethodFilter();
       methodFilter.setMethodParam("_m");
       return methodFilter;
    }
    }

2、请求映射原理

SpringMVC功能分析都从 org.springframework.web.servlet.DispatcherServlet-》doDispatch（）

protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
        HttpServletRequest processedRequest = request;
        HandlerExecutionChain mappedHandler = null;
        boolean multipartRequestParsed = false;
        WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
        try {
            ModelAndView mv = null;
            Exception dispatchException = null;
            try {
                processedRequest = checkMultipart(request);
                multipartRequestParsed = (processedRequest != request);
                // 找到当前请求使用哪个Handler（Controller的方法）处理
                mappedHandler = getHandler(processedRequest);
                //HandlerMapping：处理器映射。/xxx->>xxxx

RequestMappingHandlerMapping：保存了所有@RequestMapping 和handler的映射规则。

所有的请求映射都在HandlerMapping中。

• SpringBoot自动配置欢迎页的 WelcomePageHandlerMapping 。访问 /能访问到index.html；
• SpringBoot自动配置了默认 的 RequestMappingHandlerMapping
• 请求进来，挨个尝试所有的HandlerMapping看是否有请求信息。
• • 如果有就找到这个请求对应的handler
    已经找到DELETE的Handler
    
  • 如果没有就是下一个 HandlerMapping
• 我们需要一些自定义的映射处理，我们也可以自己给容器中放HandlerMapping。自定义 HandlerMapping

  @Nullable
    protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
        if (this.handlerMappings != null) {
            Iterator var2 = this.handlerMappings.iterator();
            while(var2.hasNext()) {
                HandlerMapping mapping = (HandlerMapping)var2.next();
                HandlerExecutionChain handler = mapping.getHandler(request);
                if (handler != null) {
                    return handler;
                }
            }
        }
        return null;
    }

普通参数与基本注解

1.1、注解：

• @PathVariable、@RequestHeader、@ModelAttribute、@RequestParam、@MatrixVariable、@CookieValue、@RequestBody
  ```java @RestController public class ParameterTestController {

//  car/2/owner/zhangsan
@GetMapping("/car/{id}/owner/{username}")
public Map<String,Object> getCar(@PathVariable("id") Integer id,
                                 @PathVariable("username") String name,
                                 @PathVariable Map<String,String> pv,
                                 @RequestHeader("User-Agent") String userAgent,
                                 @RequestHeader Map<String,String> header,
                                 @RequestParam("age") Integer age,
                                 @RequestParam("inters") List<String> inters,
                                 @RequestParam Map<String,String> params,
                                 @CookieValue("_ga") String _ga,
                                 @CookieValue("_ga") Cookie cookie){
    Map<String,Object> map = new HashMap<>();

// map.put(“id”,id); // map.put(“name”,name); // map.put(“pv”,pv); // map.put(“userAgent”,userAgent); // map.put(“headers”,header); map.put(“age”,age); map.put(“inters”,inters); map.put(“params”,params); map.put(“_ga”,_ga); System.out.println(cookie.getName()+”===>”+cookie.getValue()); return map; }

@PostMapping("/save")
public Map postMethod(@RequestBody String content){
    Map<String,Object> map = new HashMap<>();
    map.put("content",content);
    return map;
}
//1、语法： 请求路径：/cars/sell;low=34;brand=byd,audi,yd
//2、SpringBoot默认是禁用了矩阵变量的功能
//      手动开启：原理。对于路径的处理。UrlPathHelper进行解析。
//              removeSemicolonContent（移除分号内容）支持矩阵变量的
//再配置类中配置
  @Bean
public WebMvcConfigurer webMvcConfigurer() {
    return new WebMvcConfigurer() {
        @Override
        public void configurePathMatch(PathMatchConfigurer configurer) {
            UrlPathHelper urlPathHelper = new UrlPathHelper();
            //不溢出；后面的内容，矩阵变量功能就可以生效
            urlPathHelper.setRemoveSemicolonContent(false);
            configurer.setUrlPathHelper(urlPathHelper);
        }
    };
}
//3、矩阵变量必须有url路径变量才能被解析
@GetMapping("/cars/{path}")
public Map carsSell(@MatrixVariable("low") Integer low,
                    @MatrixVariable("brand") List<String> brand,
                    @PathVariable("path") String path){
    Map<String,Object> map = new HashMap<>();
    map.put("low",low);
    map.put("brand",brand);
    map.put("path",path);
    return map;
}
// /boss/1;age=20/2;age=10
@GetMapping("/boss/{bossId}/{empId}")
public Map boss(@MatrixVariable(value = "age",pathVar = "bossId") Integer bossAge,
                @MatrixVariable(value = "age",pathVar = "empId") Integer empAge){
    Map<String,Object> map = new HashMap<>();
    map.put("bossAge",bossAge);
    map.put("empAge",empAge);
    return map;
}

}

<a name="2bffb82f"></a>
## 5、视图解析与模板引擎
- 视图解析：**SpringBoot默认不支持 JSP，需要引入第三方模板引擎技术实现页面渲染。**
<a name="44c30e47"></a>
### 1、视图解析
![](https://gitee.com/ljlGitee001/pictures/raw/master/img/202203112221522.png#crop=0&crop=0&crop=1&crop=1&id=WQn1t&originHeight=264&originWidth=516&originalType=binary&ratio=1&rotation=0&showTitle=false&status=done&style=none&title=)
<a name="b3068996"></a>
#### 1、视图解析原理流程
1、目标方法处理的过程中，所有数据都会被放在 **ModelAndViewContainer 里面。包括数据和视图地址**
**2、方法的参数是一个自定义类型对象（从请求参数中确定的），把他重新放在** **ModelAndViewContainer**
**3、任何目标方法执行完成以后都会返回 ModelAndView（数据和视图地址）。**
**4、processDispatchResult  处理派发结果（页面改如何响应）**
-  1、**render**(**mv**, request, response); 进行页面渲染逻辑 
-  
   - 1、根据方法的String返回值得到 **View** 对象【定义了页面的渲染逻辑】
-  
   -  
      - 1、所有的视图解析器尝试是否能根据当前返回值得到**View**对象
      - 2、得到了  **redirect:/main.html** --> Thymeleaf new **RedirectView**()
-  
   -  
      - 3、ContentNegotiationViewResolver 里面包含了下面所有的视图解析器，内部还是利用下面所有视图解析器得到视图对象。
      - 4、view.render(mv.getModelInternal(), request, response);   视图对象调用自定义的render进行页面渲染工作
-  
   -  
      -  
         - **RedirectView 如何渲染【重定向到一个页面】**
         - **1、获取目标url地址**
-  
   -  
      -  
         - **2、response.sendRedirect(encodedURL);**
**视图解析：**
-  
   - **返回值以 forward: 开始： new InternalResourceView(forwardUrl); -->  转发request.getRequestDispatcher(path).forward(request, response);**
   - **返回值以** **redirect: 开始：** **new RedirectView() --》 render就是重定向**
-  
   - **返回值是普通字符串： new ThymeleafView（）--->**
自定义视图解析器+自定义视图； **大厂学院。**
![](https://cdn.nlark.com/yuque/0/2020/png/1354552/1605680247945-088b0f17-185c-490b-8889-103e8b4d8c07.png?x-oss-process=image%2Fwatermark%2Ctype_d3F5LW1pY3JvaGVp%2Csize_16%2Ctext_YXRndWlndS5jb20g5bCa56GF6LC3%2Ccolor_FFFFFF%2Cshadow_50%2Ct_80%2Cg_se%2Cx_10%2Cy_10#crop=0&crop=0&crop=1&crop=1&id=I1FT5&originHeight=136&originWidth=577&originalType=binary&ratio=1&rotation=0&showTitle=false&status=done&style=none&title=)
![](https://cdn.nlark.com/yuque/0/2020/png/1354552/1605680247945-088b0f17-185c-490b-8889-103e8b4d8c07.png?x-oss-process=image%2Fwatermark%2Ctype_d3F5LW1pY3JvaGVp%2Csize_16%2Ctext_YXRndWlndS5jb20g5bCa56GF6LC3%2Ccolor_FFFFFF%2Cshadow_50%2Ct_80%2Cg_se%2Cx_10%2Cy_10#crop=0&crop=0&crop=1&crop=1&id=voAK2&originHeight=136&originWidth=577&originalType=binary&ratio=1&rotation=0&showTitle=false&status=done&style=none&title=)
![](https://cdn.nlark.com/yuque/0/2020/png/1354552/1605679959020-54b96fe7-f2fc-4b4d-a392-426e1d5413de.png?x-oss-process=image%2Fwatermark%2Ctype_d3F5LW1pY3JvaGVp%2Csize_23%2Ctext_YXRndWlndS5jb20g5bCa56GF6LC3%2Ccolor_FFFFFF%2Cshadow_50%2Ct_80%2Cg_se%2Cx_10%2Cy_10#crop=0&crop=0&crop=1&crop=1&id=ngvWr&originHeight=197&originWidth=824&originalType=binary&ratio=1&rotation=0&showTitle=false&status=done&style=none&title=)
![](https://cdn.nlark.com/yuque/0/2020/png/1354552/1605679471537-7db702dc-b165-4dc6-b64a-26459ee5fd6c.png?x-oss-process=image%2Fwatermark%2Ctype_d3F5LW1pY3JvaGVp%2Csize_17%2Ctext_YXRndWlndS5jb20g5bCa56GF6LC3%2Ccolor_FFFFFF%2Cshadow_50%2Ct_80%2Cg_se%2Cx_10%2Cy_10#crop=0&crop=0&crop=1&crop=1&id=d7NKD&originHeight=217&originWidth=590&originalType=binary&ratio=1&rotation=0&showTitle=false&status=done&style=none&title=)
![](https://cdn.nlark.com/yuque/0/2020/png/1354552/1605679913592-151a616a-c754-4da3-a2c1-91dc0230a48d.png?x-oss-process=image%2Fwatermark%2Ctype_d3F5LW1pY3JvaGVp%2Csize_22%2Ctext_YXRndWlndS5jb20g5bCa56GF6LC3%2Ccolor_FFFFFF%2Cshadow_50%2Ct_80%2Cg_se%2Cx_10%2Cy_10#crop=0&crop=0&crop=1&crop=1&id=tJ2NZ&originHeight=317&originWidth=764&originalType=binary&ratio=1&rotation=0&showTitle=false&status=done&style=none&title=)
<a name="680ecbd2"></a>
### 2、模板引擎-Thymeleaf
<a name="8be32646"></a>
#### 1、thymeleaf简介
-  Thymeleaf is a modern server-side Java template engine for both web and standalone environments, capable of processing HTML, XML, JavaScript, CSS and even plain text. 
-  **现代化、服务端Java模板引擎** 
<a name="25e14243"></a>
#### 2、基本语法
<a name="15d35776"></a>
##### 1、表达式
| 表达式名字 | 语法 | 用途 |
| --- | --- | --- |
| 变量取值 | ${...} | 获取请求域、session域、对象等值 |
| 选择变量 | *{...} | 获取上下文对象值 |
| 消息 | #{...} | 获取国际化等值 |
| 链接 | @{...} | 生成链接 |
| 片段表达式 | ~{...} | jsp:include 作用，引入公共页面片段 |
<a name="366dca5b"></a>
##### 2、字面量
-  文本值: **'one text'** **,** **'Another one!'** **,…**数字: **0** **,** **34** **,** **3.0** **,** **12.3** **,…**布尔值: **true** **,** **false** 
-  空值: **null** 
-  变量： one，two，.... 变量不能有空格 
<a name="747ebdd0"></a>
##### 3、文本操作
-  字符串拼接: **+** 
-  变量替换: **|The name is ${name}|** 
<a name="fc4eaaf9"></a>
##### 4、数学运算
- 运算符: + , - , * , / , %
<a name="17e851c3"></a>
##### 5、布尔运算
-  运算符:  **and** **,** **or** 
-  一元运算: **!** **,** **not** 
<a name="ee3b4091"></a>
##### 6、比较运算
- 比较: **>** **,** **<** **,** **>=** **,** **<=** **(** **gt** **,** **lt** **,** **ge** **,** **le** **)**等式: **==** **,** **!=** **(** **eq** **,** **ne** **)**
<a name="4252a13f"></a>
##### 7、条件运算
-  If-then: **(if) ? (then)** 
-  If-then-else: **(if) ? (then) : (else)** 
-  Default: (value) **?: (defaultvalue)** 
<a name="2624a096"></a>
##### 8、特殊操作
- 无操作： _
<a name="fed8d207"></a>
#### 3、设置属性值-th:attr
-  设置单个值  
```html
<form action="subscribe.html" th:attr="action=@{/subscribe}">
  <fieldset>
    <input type="text" name="email" />
    <input type="submit" value="Subscribe!" th:attr="value=#{subscribe.submit}"/>
  </fieldset>
</form>

• 设置多个值

<img src="../../images/gtvglogo.png"  th:attr="src=@{/images/gtvglogo.png},title=#{logo},alt=#{logo}" />

• 以上两个的代替写法 th:xxxx

<input type="submit" value="Subscribe!" th:value="#{subscribe.submit}"/>
<form action="subscribe.html" th:action="@{/subscribe}">

所有h5兼容的标签写法

https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#setting-value-to-specific-attributes

4、迭代

<tr th:each="prod : ${prods}">
        <td th:text="${prod.name}">Onions</td>
        <td th:text="${prod.price}">2.41</td>
        <td th:text="${prod.inStock}? #{true} : #{false}">yes</td>
</tr>

<tr th:each="prod,iterStat : ${prods}" th:class="${iterStat.odd}? 'odd'">
  <td th:text="${prod.name}">Onions</td>
  <td th:text="${prod.price}">2.41</td>
  <td th:text="${prod.inStock}? #{true} : #{false}">yes</td>
</tr>

5、条件运算

<a href="comments.html"
th:href="@{/product/comments(prodId=${prod.id})}"
th:if="${not #lists.isEmpty(prod.comments)}">view</a>

<div th:switch="${user.role}">
  <p th:case="'admin'">User is an administrator</p>
  <p th:case="#{roles.manager}">User is a manager</p>
  <p th:case="*">User is some other thing</p>
</div>

6、属性优先级

3、thymeleaf使用

1、引入Starter

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

2、自动配置好了thymeleaf

@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(ThymeleafProperties.class)
@ConditionalOnClass({ TemplateMode.class, SpringTemplateEngine.class })
@AutoConfigureAfter({ WebMvcAutoConfiguration.class, WebFluxAutoConfiguration.class })
public class ThymeleafAutoConfiguration { }

自动配好的策略

• 1、所有thymeleaf的配置值都在 ThymeleafProperties
• 2、配置好了 SpringTemplateEngine
• 3、配好了 ThymeleafViewResolver
• 4、我们只需要直接开发页面

    public static final String DEFAULT_PREFIX = "classpath:/templates/";
    public static final String DEFAULT_SUFFIX = ".html";  //xxx.html