Spring控制反转（IOC）和注入（DI）

2020-10-17  本文已影响0人  凡哥爱丽姐

例1、DI注入，通过set方法注入值

1.1、添加依赖pom.xml

 <dependencies>
        <!-- Spring的核心工具包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <!--在基础IOC功能上提供扩展服务，还提供许多企业级服务的支持，有邮件服务、任务调度、远程访问、缓存以及多种视图层框架的支持-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

        <!-- Spring IOC的基础实现，包含访问配置文件、创建和管理bean等 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

        <!-- Spring context的扩展支持，用于MVC方面 -->

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <!-- Spring表达式语言 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>

1.2、User实体类

package com.fan.entity;

public class User {
    private String name;
    private Integer age;

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public Integer getAge() {
        return age;
    }
}

1.3、UserController类

package com.fan.controller;

import com.fan.entity.User;

public class UserController {
    private User user1;

    public void setUser1(User user1) {
        this.user1 = user1;
    }

    public User getUser1(){
        return user1;
    }
}

1.4、UserTest类

public class UserTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("applicationContext.xml");
        UserController userController =(UserController)applicationContext.getBean("usercontroller");
        System.out.println(userController);//com.fan.controller.UserController@4973813a
        System.out.println(userController.getUser1().getName()+" "+userController.getUser1().getAge());//韦凡 11

        User user = (User)applicationContext.getBean("user");
        System.out.println(user.getName()+" "+user.getAge());//韦凡 11
    }
}

1.5、配置applicationContext.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
                           http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="user" class="com.fan.entity.User">      <!--创建一个user对象-->
        <property name="name" value="韦凡" ></property>     <!-- DI注入 通过set方法注入值-->
        <property name="age" value="11"></property>
    </bean>
    <bean id="usercontroller" class="com.fan.controller.UserController">
        <property name="user1" ref="user"></property>
    </bean>
</beans>

例2、DI注入，通过构造方法注入值

2.1、添加依赖pom.xml

<dependencies>
        <!-- Spring的核心工具包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <!--在基础IOC功能上提供扩展服务，还提供许多企业级服务的支持，有邮件服务、任务调度、远程访问、缓存以及多种视图层框架的支持-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

        <!-- Spring IOC的基础实现，包含访问配置文件、创建和管理bean等 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

        <!-- Spring context的扩展支持，用于MVC方面 -->

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <!-- Spring表达式语言 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>

2.2、定义一个Person类(User类是上面的)

package com.fan.entity;

public class Person {
    private String name;
    private Integer age;
    private User user;

    //构造方法注入DI
    public Person(String name,Integer age,User user){
        this.name=name;
        this.age=age;
        this.user=user;
    }


    public String getName() {
        return name;
    }

    public Integer getAge() {
        return age;
    }

    public User getUser() {
        return user;
    }
}

2.3、PersonTest类

public class PersonTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("applicationContext.xml");
   
       //构造方法注入测试
        Person person = (Person)applicationContext.getBean("person");
        System.out.println(person.getName()+" "+person.getAge()+" 她的学生是："+person.getUser().getName());
    }
}

2.4、配置applicationContext.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
                           http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="user" class="com.fan.entity.User">      <!--创建一个user对象-->
        <property name="name" value="韦凡" ></property>     <!-- DI注入 通过set方法注入值-->
        <property name="age" value="11"></property>
    </bean>

    <!--构造方法注入-->
    <bean id="person" class="com.fan.entity.Person">
        <constructor-arg name="name" value="红红" type="java.lang.String"></constructor-arg> <!--通过构造方法注入-->
        <constructor-arg name="age" value="50"></constructor-arg>
        <constructor-arg name="user" ref="user"></constructor-arg>    <!-- 引用属性类型值注入-->
    </bean>
</beans>

例3、p命名空间注入(需要调用set方法注入)

3.1、在pom.xml添加依赖的jar包

<dependencies>
        <!-- Spring的核心工具包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <!--在基础IOC功能上提供扩展服务，还提供许多企业级服务的支持，有邮件服务、任务调度、远程访问、缓存以及多种视图层框架的支持-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

        <!-- Spring IOC的基础实现，包含访问配置文件、创建和管理bean等 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

        <!-- Spring context的扩展支持，用于MVC方面 -->

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <!-- Spring表达式语言 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>

3.2、定义个Man类(User类时例1中的)

package com.fan.entity;

public class Man {
    private String name;
    private Integer age;
    private User user;

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public void setUser(User user) {
        this.user = user;
    }


    public String getName() {
        return name;
    }

    public Integer getAge() {
        return age;
    }

    public User getUser() {
        return user;
    }
}

3.3、创建一个ManTest类

public class UserTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("applicationContext.xml");
  
       //p命名空间注入测试
        Man man=(Man)applicationContext.getBean("man");
        System.out.println(man.getName()+" "+man.getAge());
    }
}

3.4、applicationContext.xml配置

<?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:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
                           http://www.springframework.org/schema/beans/spring-beans.xsd">


    <!--p命名空间注入-->
    <bean id="man" class="com.fan.entity.Man" p:name="龙哥" p:age="50"  p:user-ref="user"></bean><!--p命名空间注入  通过set方法注入值-->
</beans>

需要注意配置文件中添加命名空间p （这是与上面文件不同的地方）xmlns:p="http://www.springframework.org/schema/p"

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