Spring SpringMVC Mybatis框架配置

一、简介

• SSM是目前比较流行的Java Web框架，具体我就不多介绍了，网上一大堆。但是关于SSM的配置，网上很多教程使用的是比较老的Spring版本，总会有问题。本文的目的是帮助读者快速搭建起一套SSM的环境，而并非解析该框架或者说清楚每处配置的具体含义。

二、环境要求

• JDK 11（1.8以上应该都适用）
• Eclipse - Java EE，2019-03
• Spring Framework 5.1.6.RELEASE
• Mybatis 3.5.1
• Tomcat 9.0.x

三、配置Gradle项目

• 首先我们新建项目，在项目列表中选择Others，然后搜索“Gradle”，选择Gradle Project，如果找不到Gradle Project，请升级你的Eclipse版本。这里不对单独安装Gradle进行说明。
• 按照默认配置进行Gradle Project设置即可，可以自己定义项目名称更改项目位置，直到创建完成。这样我们便得到了一个Gradle Project项目。

四、配置Dynamic Web Module项目

• 这时候我们得到的仅仅是一个Gradle项目，如果你是做普通的Java SE开发，那么到这就可以关掉了。但是我们是要配置SSM，而SSM是基于Java EE的项目的。所以我们在项目上右击，选择最下面的Properties，然后在左侧边栏找到Project Facets，这时候Eclipse会提示我们说“This project is not configured to use project facets. Converting this project to faceted form will allow you to easily control the available technologies.”，我们直接点击下面的Convent to faceted from，就得到了一个菜单。
• 在这个菜单里我们找到Dynamic Web Module，然后勾选它，右侧可以选择版本，默认是3.0，可以选更高的版本比如3.1或者4.0,当然就需要更高的Tomcat版本来支持（例如4.0只支持Tomcat 9.x），这里我们选的是4.0。
• 这时候先不要急着点击Apply，下面会出现一个“Further configuration avaliable”的按钮，我们点击他来进行Dynamic Web Module的配置，这样可以节省一些步骤。
• 在弹出的窗口中，其他选项保持不动，然后勾选“Generate web.xml deployment descriptor”，这样Eclipse会自动为我们生成web.xml这个文件，方便我们配置Servlet等Java EE组件，然后确定退出即可。

五、配置build.gradle

• 上一个步骤我们得到了一个基于Gradle的Dynamic Web Module项目，然后我们就开始配置SSM。首先打开build.gradle配置我们需要的包，除了必须的SSM组件之外还包括一些加解密、JSON序列化、文件上传所用的包。这里将不在解释每个包是干什么用的，就先贴出来，这样的配置对于常规的Java Web应用都足够了。

/*
 * This build file was generated by the Gradle 'init' task.
 *
 * This generated file contains a sample Java Library project to get you started.
 * For more details take a look at the Java Libraries chapter in the Gradle
 * user guide available at https://docs.gradle.org/4.3/userguide/java_library_plugin.html
 */
// Apply the java-library plugin to add support for Java Library
apply plugin: 'java-library'
// Apply the war plugin to add support for Java Web war package
apply plugin: 'war'
// In this section you declare where to find the dependencies of your project
repositories {
    // Use jcenter for resolving your dependencies.
    // You can declare any Maven/Ivy/file repository here.
    jcenter()
}
dependencies {
// https://mvnrepository.com/artifact/mysql/mysql-connector-java
compile group: 'mysql', name: 'mysql-connector-java', version: '8.0.15'
// https://mvnrepository.com/artifact/commons-codec/commons-codec
compile group: 'commons-codec', name: 'commons-codec', version: '1.12'
// https://mvnrepository.com/artifact/org.apache.commons/commons-collections4
compile group: 'org.apache.commons', name: 'commons-collections4', version: '4.3'
// https://mvnrepository.com/artifact/commons-logging/commons-logging
compile group: 'commons-logging', name: 'commons-logging', version: '1.2'
// https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-core
compile group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.11.2'
// https://mvnrepository.com/artifact/org.springframework/spring-core
compile group: 'org.springframework', name: 'spring-core', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-beans
compile group: 'org.springframework', name: 'spring-beans', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-web
compile group: 'org.springframework', name: 'spring-web', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-webmvc
compile group: 'org.springframework', name: 'spring-webmvc', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-jdbc
compile group: 'org.springframework', name: 'spring-jdbc', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-aop
compile group: 'org.springframework', name: 'spring-aop', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-aspects
compile group: 'org.springframework', name: 'spring-aspects', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-context-support
compile group: 'org.springframework', name: 'spring-context-support', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-instrument
compile group: 'org.springframework', name: 'spring-instrument', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-instrument-tomcat
compile group: 'org.springframework', name: 'spring-instrument-tomcat', version: '4.3.22.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-jms
compile group: 'org.springframework', name: 'spring-jms', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-messaging
compile group: 'org.springframework', name: 'spring-messaging', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-orm
compile group: 'org.springframework', name: 'spring-orm', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-oxm
compile group: 'org.springframework', name: 'spring-oxm', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-test
testCompile group: 'org.springframework', name: 'spring-test', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-tx
compile group: 'org.springframework', name: 'spring-tx', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-webmvc
compile group: 'org.springframework', name: 'spring-webmvc', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework/spring-websocket
compile group: 'org.springframework', name: 'spring-websocket', version: '5.1.6.RELEASE'
// https://mvnrepository.com/artifact/org.springframework.security/spring-security-core
compile group: 'org.springframework.security', name: 'spring-security-core', version: '5.1.5.RELEASE'
// https://mvnrepository.com/artifact/org.springframework.security/spring-security-web
compile group: 'org.springframework.security', name: 'spring-security-web', version: '5.1.5.RELEASE'
// https://mvnrepository.com/artifact/org.springframework.security/spring-security-config
compile group: 'org.springframework.security', name: 'spring-security-config', version: '5.1.5.RELEASE'
// https://mvnrepository.com/artifact/org.apache.commons/commons-dbcp2
compile group: 'org.apache.commons', name: 'commons-dbcp2', version: '2.6.0'
// https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload
compile group: 'commons-fileupload', name: 'commons-fileupload', version: '1.4'
// https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils
compile group: 'commons-beanutils', name: 'commons-beanutils', version: '1.9.3'
// https://mvnrepository.com/artifact/commons-codec/commons-codec
compile group: 'commons-codec', name: 'commons-codec', version: '1.12'
// https://mvnrepository.com/artifact/org.apache.commons/commons-collections4
compile group: 'org.apache.commons', name: 'commons-collections4', version: '4.3'
// https://mvnrepository.com/artifact/org.apache.commons/commons-lang3
compile group: 'org.apache.commons', name: 'commons-lang3', version: '3.8.1'
// https://mvnrepository.com/artifact/org.mybatis/mybatis-spring
compile group: 'org.mybatis', name: 'mybatis-spring', version: '2.0.1'
// https://mvnrepository.com/artifact/org.mybatis/mybatis
compile group: 'org.mybatis', name: 'mybatis', version: '3.5.1'
// https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api
compile group: 'javax.servlet', name: 'javax.servlet-api', version: '4.0.1'
// https://mvnrepository.com/artifact/org.json/json
compile group: 'org.json', name: 'json', version: '20180813'
// https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind
compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.8'
// https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core
compile group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.9.8'
// https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk15on
compile group: 'org.bouncycastle', name: 'bcprov-jdk15on', version: '1.61'
}

• 在保存build.gradle之后，右击项目，在Gradle菜单中选择Refresh Gradle Project，就可以下载依赖了，该过程需要网络连接。

六、配置web.xml

• 在web.xml里，我们要为Spring MVC配置Servlet，Spring MVC是单Servlet的结构，所以我们配置如下，同样地不过多解释每个配置的详细含义。

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
<display-name>SecIoT</display-name>
<!-- 欢迎文件，设置在直接访问路径的时候默认寻找的文件名称 -->
<welcome-file-list>
    <welcome-file>index.html</welcome-file>
</welcome-file-list>
<!-- Spring的字符编码过滤器 -->
<filter>
    <filter-name>Character Encoding</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
</filter>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
    <listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>
</listener>
<!-- 配置Spring配置文件的位置 -->
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/spring/*.xml</param-value>
</context-param>
<!-- 配置Spring MVC的DispatcherServlet以及其配置文件的位置 -->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/springmvc-config.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<!-- 配置Spring MVC的Servlet映射 -->
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>
<!-- 配置Spring Security过滤器，如不需要登录和身份认证可以去掉 -->
<filter> 
    <filter-name>springSecurityFilterChain</filter-name> 
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> 
</filter> 
<filter-mapping> 
    <filter-name>springSecurityFilterChain</filter-name> 
    <url-pattern>/*</url-pattern> 
</filter-mapping>
</web-app>

七、配置Spring MVC配置文件

• 根据web.xml的配置，我们需要在对应路径创建Spring MVC配置文件，首先我们创建/WEB-INF/spring/springmvc-config.xml，先新建文件夹再新建xml文件，该文件的配置内容如下。

<?xml version="1.0" encoding="UTF-8"?>
<beans default-lazy-init="true"
    xmlns="http://www.springframework.org/schema/beans" 
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
       http://www.springframework.org/schema/beans   
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd  
       http://www.springframework.org/schema/mvc   
       http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd   
       http://www.springframework.org/schema/context  
       http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <!-- 配置组件扫描的包为项目的全部包 -->
    <context:component-scan base-package="com.wrlus.seciot"/>
    <!-- 配置默认Servlet Handler -->
    <mvc:default-servlet-handler />
    <!-- 启用注解扫描功能 -->
    <mvc:annotation-driven />
    <!-- 启用基于commons-fileupload的文件上传功能 -->
    <bean id="multipartResolver" 
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
        p:defaultEncoding="UTF-8" />
</beans>

• 这里说下网上一个流传较广的配置，即配置InternelRecourceViewResolver的prefix和suffix，分别为”/WEB-INF/jsp“和“.jsp”，他的功能仅仅是让你在访问某个链接的时候自动跳到对应的JSP文件执行。而这里我们完全不使用JSP，而是采用前后端分离的方式，所以不需要这样的配置。

八、配置Spring配置文件

• 配置好了Spring MVC，我们再进行Spring的配置并整合Mybatis。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://www.springframework.org/schema/beans" 
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
                        http://www.springframework.org/schema/jdbc 
                        http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
                        http://www.springframework.org/schema/context   
                        http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <!-- 主要数据库的配置 -->
    <bean id="mainDataSource" class="org.apache.commons.dbcp2.BasicDataSource"
        destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost/seciot?serverTimezone=UTC" />
        <property name="username" value="root" /> 
        <property name="password" value="*********" /> 
    </bean>
    <!-- 认证数据库的配置 -->
    <bean id="securityDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost/seciot?serverTimezone=UTC" />
        <property name="username" value="root" /> 
        <property name="password" value="*********" />
    </bean>
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="mainDataSource" />
        <property name="configLocation" value="/WEB-INF/mybatis/mybatis-config.xml" />
        <property name="mapperLocations" value="classpath:com/wrlus/seciot/*/dao/*.xml" />
    </bean>
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.wrlus.seciot" />
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
    </bean>
</beans>

• 这里面有两个数据库的配置，其中第一个是为Mybatis而配置，第二个是为Spring Security而配置，如果没有用到Spring Security则可以删除第二个bean，而且如果使用的是Mybatis的注解方法而不是xml方法，还可以省略mapperLocations。而且同时如果需要在启动和关闭服务器的时候自动做一些操作，也可以再添加其他的Bean。

九、配置Mybatis配置文件

• Mybatis其实没什么需要配置的，但是配置文件好像必须得有：/WEB-INF/mybatis/mybatis-config.xml。

<?xml version="1.0" encoding="UTF-8" ?>  
<!DOCTYPE configuration  
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"  
"http://mybatis.org/dtd/mybatis-3-config.dtd">  
<configuration>
</configuration>

十、配置Spring Security配置文件（可选）

• Spring Security可以根据自己的需求来配置：/WEB-INF/spring/spring-security.xml

<b:beans xmlns="http://www.springframework.org/schema/security"
    xmlns:b="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/security 
        http://www.springframework.org/schema/security/spring-security.xsd">
    <!-- 无条件允许访问css路径 -->
    <http pattern="/css/**" security="none" />
    <!-- 无条件允许访问js路径 -->
    <http pattern="/js/**" security="none" />
    <!-- 配置访问权限控制 -->
    <http auto-config="true" use-expressions="true">
        <!-- 所有路径必须经过鉴权才可访问 -->
        <intercept-url pattern="/**" access="authenticated" />
        <!-- 无条件禁止访问uploads路径 -->
        <intercept-url pattern="/attach/uploads/**" access="none" />
        <!-- 开启XSS防护 -->
        <headers>
            <xss-protection />
        </headers>
        <!-- 配置默认目标，此处还可以配置替换默认的登录页面和自定义注销页面 -->
        <form-login default-target-url="/index.html" always-use-default-target="true" />
        <!-- 关闭CSRF防护，如需开启需要配置jsp文件 -->
        <csrf disabled="true" />
    </http>
    <!-- 认证管理器 -->
    <authentication-manager>
        <!-- 配置认证提供者为JDBC，并指明数据源的bean和密码编码方式 -->
        <authentication-provider>
            <jdbc-user-service data-source-ref="securityDataSource"/>
            <password-encoder ref="passwordEncoder" />
        </authentication-provider>
    </authentication-manager>
    <!-- 配置密码为明文存储，请勿用于生产用途，如需哈希加盐存储可更换class，有SHA-1等算法可选 -->
    <b:bean id="passwordEncoder"
        class="org.springframework.security.crypto.password.NoOpPasswordEncoder" 
        factory-method="getInstance"/>
</b:beans>

• 另外数据库表需要两个，一个存储用户，一个存储角色，因为Spring Security是基于角色的权限控制。

CREATE TABLE `users` (
  `username` varchar(50) NOT NULL,
  `password` varchar(256) NOT NULL,
  `enabled` tinyint(1) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `authorities` (
  `username` varchar(50) NOT NULL,
  `authority` varchar(50) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

十一、配置log4j配置文件

• 为了显示日志需要配置log4j2,在源代码目录下创建log4j2.xml，内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/2002/xmlspec/dtd/2.10/xmlspec.dtd">
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout
                pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <!-- 日志级别为Debug，生产系统请更改为Warn以上级别 -->
        <Root level="Debug">
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration>

十二、请求映射实例

• 截止上面SSM的配置就完成了，但是需要代码运作还需要编写Java代码，下面给出一个请求映射的实际例子。

package com.wrlus.seciot.dashboard.controller;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.wrlus.seciot.util.Status;

@Controller
@RequestMapping("/dashboard")
public class DashboardController {

    @ResponseBody
    @RequestMapping("/refresh")
    public Map<String, Object> refresh(HttpServletRequest request, HttpServletResponse response) {
        Map<String, Object> data=new HashMap<String, Object>();
        data.put("Status", Status.SUCCESS);
        return data;
    }
}

• 其中关键点为@Controller注解，这样该类会被Spring容器自动实例化。然后则是两个RequestMapping，这样配置的话，这个方法所拦截的请求就是：http://[host:port]/[project_name]/dashboard/refresh，同时配置@ResponseBody注解表示这个类直接返回一个JSON或者XML的形式，更方便前端或者移动客户端做处理。

十三、数据库映射实例

• 除此之外再给出一个Mybatis数据库映射的实例，这种映射一般需要四个包，分别为controller，service，dao和model，其中dao这个名字是可以在Spring配置文件中配置的。

package com.wrlus.seciot.platform.model;

public class PlatformRiskDao {
    private String id;
    private String name;
    private String description;
    private String level;
    private String platform;
    private String payload;
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public String getLevel() {
        return level;
    }
    public void setLevel(String level) {
        this.level = level;
    }
    public String getPlatform() {
        return platform;
    }
    public void setPlatform(String platform) {
        this.platform = platform;
    }
    public String getPayload() {
        return payload;
    }
    public void setPayload(String payload) {
        this.payload = payload;
    }

}

package com.wrlus.seciot.platform.service;

import java.util.List;

import com.wrlus.seciot.platform.model.PlatformRiskDao;

public interface PlatformRiskService {
    public List<PlatformRiskDao> getPlatformRiskAll();
    public List<PlatformRiskDao> getPlatformRiskById(String id);
    public List<PlatformRiskDao> getPlatformRiskByCategory(String category);
}

package com.wrlus.seciot.platform.service;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.wrlus.seciot.platform.dao.PlatformRiskMapper;
import com.wrlus.seciot.platform.model.PlatformRiskDao;

@Service
public class PlatformRiskServiceImpl implements PlatformRiskService {
    @Autowired
    private PlatformRiskMapper dao;

    @Override
    public List<PlatformRiskDao> getPlatformRiskAll() {
        return dao.getPlatformRiskAll();
    }

    @Override
    public List<PlatformRiskDao> getPlatformRiskById(String id) {
        return dao.getPlatformRiskById(id);
    }

    @Override
    public List<PlatformRiskDao> getPlatformRiskByCategory(String category) {
        return dao.getPlatformRiskByCategory(category);
    }
}

package com.wrlus.seciot.platform.dao;

import java.util.List;

import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import com.wrlus.seciot.platform.model.PlatformRiskDao;

@Repository
public interface PlatformRiskMapper {
    @Select("select * from platform_risk;")
    public List<PlatformRiskDao> getPlatformRiskAll();

    @Select("select * from platform_risk where id = #{id};")
    public List<PlatformRiskDao> getPlatformRiskById(@Param("id") String id);

    @Select("select * from platform_risk where id in (select id from platform_risk_category where category = #{category});")
    public List<PlatformRiskDao> getPlatformRiskByCategory(@Param("category") String category);

}

• 其中@Autowired
  ，@Service注解不能忘记，如果忽略了会找不到这些类，另外在Mapper中，如果需要其他语句也可直接使用@Insert，@Update和@Delete，但要注意返回值为int类型。同时如果传入参数为model对象，则不需要@Param，只需要参数名字和model中名称以及数据库中列名对应即可。如果为基本类型，就需要@Param