概念

  • 依赖注入（Dependency Injection,DI）
  • 依赖 : 指Bean对象的创建依赖于容器 . Bean对象的依赖资源
  • 注入 : 指Bean对象所依赖的资源 , 由容器来设置和装配

    1. 构造器注入

    我们在之前的案例已经讲过了

    2. Set方式注入【重点】

    【环境搭建】
  1. 复杂类型属性
  2. 真实测试对象

要求被注入的属性，必须有set方法，set方法的方法名有set +属性首字母大写，如果属性是boolean类型，没有set方法，是is

1）pojo包

  1. public class Address {
  2.     private String address;
  4.     public String getAddress() {
  5.         return address;
  6.     }
  8.     public void setAddress(String address) {
  9.         this.address = address;
  10.     }
  11. }
  1. package cn.edu.jxust.pojo;
  3. import java.util.*;
  5. public class Student {
  6.     private String name;
  7.     private Address address;
  8.     private String[] books;
  9.     private List<String> hobbys;
  10.     private Map<String,String> card;
  11.     private Set<String> game;
  12.     private String wife;
  13.     private Properties info;
  15.     @Override
  16.     public String toString() {
  17.         return "Student{" +
  18.                 "name='" + name + '\'' +
  19.                 ", address=" + address +
  20.                 ", books=" + Arrays.toString(books) +
  21.                 ", hobbys=" + hobbys +
  22.                 ", card=" + card +
  23.                 ", game=" + game +
  24.                 ", wife='" + wife + '\'' +
  25.                 ", info=" + info +
  26.                 '}';
  27.     }
  29.     public String getName() {
  30.         return name;
  31.     }
  33.     public void setName(String name) {
  34.         this.name = name;
  35.     }
  36. }

2）beans.xml文件

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans"
  3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.        xsi:schemaLocation="http://www.springframework.org/schema/beans
  5.                            https://www.springframework.org/schema/beans/spring-beans.xsd">
  6.   <!--    第一种，普通值注入，value-->
  7.   <bean id="student" class="cn.edu.jxust.pojo.Student">
  8.     <property name="name" value="浔阳江头月送客，枫叶荻花秋瑟瑟" />
  9.   </bean>
  10. </beans>

3)MyTest测试

  1. import cn.edu.jxust.pojo.Student;
  2. import org.springframework.context.ApplicationContext;
  3. import org.springframework.context.support.ClassPathXmlApplicationContext;
  5. public class MyTest {
  6.     public static void main(String[] args) {
  7.         ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
  8.         Student student = (Student) context.getBean("student");
  9.         System.out.println(student.getName());
  10.     }
  11. }

3. 拓展方式注入

常量注入、Bean注入、数组、List、Map、Set注入、Null注入、properties注入、p命名和c命名

1）beans.xml文件

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans"
  3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.        xsi:schemaLocation="http://www.springframework.org/schema/beans
  5.                            https://www.springframework.org/schema/beans/spring-beans.xsd">
  6.   <bean id="address" class="cn.edu.jxust.pojo.Address" />
  7.   <!--    第一种，普通值注入，value-->
  8.   <bean id="student" class="cn.edu.jxust.pojo.Student">
  9.     <property name="name" value="浔阳江头月送客，枫叶荻花秋瑟瑟" />
  10.     <!--        第二种，Bean注入，ref-->
  11.     <property name="address" ref="address" />
  12.     <!--        数组-->
  13.     <property name="books">
  14.       <array>
  15.         <value>红楼梦</value>
  16.         <value>西游记</value>
  17.         <value>三国</value>
  18.         <value>三国演义</value>
  19.       </array>
  20.     </property>
  21.     <!--        List-->
  22.     <property name="hobbys">
  23.       <list>
  24.         <value>听歌</value>
  25.         <value>敲代码</value>
  26.         <value>看电影</value>
  27.       </list>
  28.     </property>
  29.     <!--        Map-->
  30.     <property name="card">
  31.       <map>
  33.         <entry key="身份证" value="361127200000000000"/>
  34.         <entry key="银行卡" value="555555555555555555" />
  35.       </map>
  36.     </property>
  37.     <!--        set注入-->
  38.     <property name="game">
  39.       <set>
  40.         <value>LOL</value>
  41.         <value>BOB</value>
  42.         <value>COC</value>
  43.       </set>
  44.     </property>
  45.     <!--    null注入-->
  46.     <property name="wife">
  47.       <null />
  48.     </property>
  49.     <property name="info">
  50.       <props>
  51.         <prop key="学号">57200181636</prop>
  52.         <prop key="性别">男</prop>
  53.       </props>
  54.     </property>
  55.   </bean>
  57. </beans>

2）pojo包

  1. package cn.edu.jxust.pojo;
  3. public class Address {
  4.     private String address;
  6.     public String getAddress() {
  7.         return address;
  8.     }
  10.     public void setAddress(String address) {
  11.         this.address = address;
  12.     }
  14.     @Override
  15.     public String toString() {
  16.         return "Address{" +
  17.                 "address='" + address + '\'' +
  18.                 '}';
  19.     }
  20. }
  1. package cn.edu.jxust.pojo;
  3. import java.util.*;
  5. public class Student {
  6.     private String name;
  7.     private Address address;
  8.     private String[] books;
  9.     private List<String> hobbys;
  10.     private Map<String,String> card;
  11.     private Set<String> game;
  12.     private String wife;
  13.     private Properties info;
  17.     public String getName() {
  18.         return name;
  19.     }
  21.     public void setName(String name) {
  22.         this.name = name;
  23.     }
  25.     public Address getAddress() {
  26.         return address;
  27.     }
  29.     public void setAddress(Address address) {
  30.         this.address = address;
  31.     }
  33.     public String[] getBooks() {
  34.         return books;
  35.     }
  37.     public void setBooks(String[] books) {
  38.         this.books = books;
  39.     }
  41.     public List<String> getHobbys() {
  42.         return hobbys;
  43.     }
  45.     public void setHobbys(List<String> hobbys) {
  46.         this.hobbys = hobbys;
  47.     }
  49.     public Map<String, String> getCard() {
  50.         return card;
  51.     }
  53.     public void setCard(Map<String, String> card) {
  54.         this.card = card;
  55.     }
  57.     public Set<String> getGame() {
  58.         return game;
  59.     }
  61.     public void setGame(Set<String> game) {
  62.         this.game = game;
  63.     }
  65.     public String getWife() {
  66.         return wife;
  67.     }
  69.     public void setWife(String wife) {
  70.         this.wife = wife;
  71.     }
  73.     public Properties getInfo() {
  74.         return info;
  75.     }
  77.     public void setInfo(Properties info) {
  78.         this.info = info;
  79.     }
  81.     @Override
  82.     public String toString() {
  83.         return "Student{" +
  84.                 "name='" + name + '\'' +
  85.                 ", address=" + address.toString() +
  86.                 ", books=" + Arrays.toString(books) +
  87.                 ", hobbys=" + hobbys +
  88.                 ", card=" + card +
  89.                 ", game=" + game +
  90.                 ", wife='" + wife + '\'' +
  91.                 ", info=" + info +
  92.                 '}';
  93.     }
  94. }

3）测试

  1. import cn.edu.jxust.pojo.Student;
  2. import org.springframework.context.ApplicationContext;
  3. import org.springframework.context.support.ClassPathXmlApplicationContext;
  5. public class MyTest {
  6.     public static void main(String[] args) {
  7.         ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
  8.         Student student = (Student) context.getBean("student");
  9.         System.out.println(student.toString());
  10.         /*
  11.         Student{
  12.         name='浔阳江头月送客，枫叶荻花秋瑟瑟',
  13.         address=Address{address='null'},
  14.         books=[红楼梦, 西游记, 三国, 三国演义],
  15.         hobbys=[听歌, 敲代码, 看电影],
  16.         card={
  17.             身份证=361127200000000000,
  18.             银行卡=555555555555555555
  19.         },
  20.         game=[LOL, BOB, COC],
  21.         wife='null',
  22.         info={学号=57200181636,
  23.         性别=男}
  24.         }
  25.          */
  26.     }
  27. }

4）p命名和c命名注入

4.1 p命名（运用无参）

P命名空间注入 : 需要在头文件中加入约束文件 导入约束 : xmlns:p=”http://www.springframework.org/schema/p”

User类
  1. package cn.edu.jxust.pojo;
  3. public class User {
  4.     private String name;
  5.     private int age;
  7.     public String getName() {
  8.         return name;
  9.     }
  11.     public void setName(String name) {
  12.         this.name = name;
  13.     }
  15.     public int getAge() {
  16.         return age;
  17.     }
  19.     public void setAge(int age) {
  20.         this.age = age;
  21.     }
  23.     @Override
  24.     public String toString() {
  25.         return "User{" +
  26.             "name='" + name + '\'' +
  27.             ", age=" + age +
  28.             '}';
  29.     }
  30. }

userbeans.xml
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans"
  3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.        xmlns:p="http://www.springframework.org/schema/p"
  5.        xsi:schemaLocation="http://www.springframework.org/schema/beans
  6.                            https://www.springframework.org/schema/beans/spring-beans.xsd">
  7.   <!--P(属性: properties)命名空间 , 属性依然要设置set方法-->
  8.   <bean id="user" class="cn.edu.jxust.pojo.User" p:name="杨辉" p:age="18" />
  9. </beans>

4.2 c命名（运用有参）

c 命名空间注入 : 需要在头文件中加入约束文件 导入约束 : xmlns:c=”http://www.springframework.org/schema/c”

User类
  1. package cn.edu.jxust.pojo;
  3. public class User {
  4.     private String name;
  5.     private int age;
  7.     public User(){
  9.     }
  10.     //与p不同，多了有参构造函数
  11.     public User(String name, int age){
  12.         this.name = name;
  13.         this.age = age;
  14.     }
  15.     public String getName() {
  16.         return name;
  17.     }
  19.     public void setName(String name) {
  20.         this.name = name;
  21.     }
  23.     public int getAge() {
  24.         return age;
  25.     }
  27.     public void setAge(int age) {
  28.         this.age = age;
  29.     }
  31.     @Override
  32.     public String toString() {
  33.         return "User{" +
  34.                 "name='" + name + '\'' +
  35.                 ", age=" + age +
  36.                 '}';
  37.     }
  38. }

userbeans.xml
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans"
  3.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.        xmlns:p="http://www.springframework.org/schema/p"
  5.        xmlns:c="http://www.springframework.org/schema/c"
  6.        xsi:schemaLocation="http://www.springframework.org/schema/beans
  7.                            https://www.springframework.org/schema/beans/spring-beans.xsd">
  8.   <!--P(属性: properties)命名空间 , 属性依然要设置set方法-->
  9.   <bean id="user" class="cn.edu.jxust.pojo.User" p:name="杨辉" p:age="18" />
  10.   <!--C(构造: Constructor)命名空间 , 属性依然要设置set方法-->
  11.   <bean id="user2" class="cn.edu.jxust.pojo.User" c:name="杨杨" c:age="19" />
  12. </beans>

4.3 MyTest测试

  1. import cn.edu.jxust.pojo.Student;
  2. import cn.edu.jxust.pojo.User;
  3. import org.junit.Test;
  4. import org.springframework.context.ApplicationContext;
  5. import org.springframework.context.support.ClassPathXmlApplicationContext;
  7. public class MyTest {
  8.     @Test
  9.     public void Test(){
  10.         ApplicationContext context = new ClassPathXmlApplicationContext("userbeans.xml");
  11.         //p命名操作
  12.         User user = (User) context.getBean("user");
  13.         //c命名操作
  14.         User user = (User) context.getBean("user2");
  15.         System.out.println(user.toString());
  16.     }
  17. }

5）Bean的作用域

image.png

5.1 单例模式（spring默认机制）

  1. <bean id="ServiceImpl" class="cn.csdn.service.ServiceImpl" scope="singleton">

5.2 原型模式

每次从容器中get的时候，都会产生一个新对象！

  1. <bean id="accountService" class="com.something.DefaultAccountService" scope="prototype"

5.3 其余的request、session、application，这些个只能在web开发中使用到！