SpringDI--依赖注入（配置文件方式）

方式一：Set注入

UserDao:

package com.spring.demo02;

public class UserDao {
    public void save() {
        System.out.println("持久层。。。");
    }
}

UserService:

package com.spring.demo02;

public class UserService {
    //配置文件注入：提供成员属性,设置set方法
    private UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    public void save() {
        System.out.println("业务层。。。");
        //调用
        userDao.save();
    }
}

配置文件设置依赖注入：

<?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">

       <!-- 演示的依赖注入 -->
       <bean id="userDao" class="com.spring.demo02.UserDao"/>

       <bean id="userService" class="com.spring.demo02.UserService">
           <property name="userDao" ref="userDao"/>
       </bean>

</beans>

测试依赖注入：

package com.spring.demo02;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestDI {
    @Test
    public void run() {
        //创建容器对象，加载配置文件，创建userDao对象，userService也被创建
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取userService对象
        UserService userService = (UserService) context.getBean("userService");
        //调用save方法
        userService.save();
    }
}

运行结果：

方式二：构造函数注入

User：

package com.spring.demo03;

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

    public User(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "User [name=" + name + ", age=" + age + "]";
    }

}

配置文件设置依赖注入：

<?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">

       <!-- 方式一：Set注入 -->
       <bean id="userDao" class="com.spring.demo02.UserDao"/>

       <bean id="userService" class="com.spring.demo02.UserService">
           <property name="userDao" ref="userDao"/>
       </bean>

       <!-- 方式二：构造方法的注入方式:name是属性名称，value是注入的值，如果要出入引用使用raf标签 -->
       <bean id="user" class="com.spring.demo03.User">
           <constructor-arg name="name" value="Tom"/>
           <constructor-arg name="age" value="18"/>

           <!-- 第二种方式  index写序号就行 -->
           <!-- <constructor-arg index="0" value="Tom"/>
           <constructor-arg name="1" value="18"/> -->

       </bean>

测试：

package com.spring.demo03;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestDI {
    @Test
    public void run() {
        //创建容器对象，加载配置文件，创建User类的对象，并构造函数初始化
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取user对象
        User user = (User) context.getBean("user");
        System.out.println(user);
    }
}

运行结果：

方式三：p命名空间注入方式

User:

package com.spring.demo03;

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;
    }

    @Override
    public String toString() {
        return "User [name=" + name + ", age=" + age + "]";
    }

}

配置文件设置依赖注入：

<?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">

    <!-- 方式三：p命名空间注入方式 -->
    <bean id="user" class="com.spring.demo03.User" p:name="Tom" p:age="18" />        

</beans>

配置文件中需要设置命名空间p

测试:

package com.spring.demo03;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestDI {
    @Test
    public void run() {
        //创建容器对象，加载配置文件，创建User类的对象，并构造函数初始化
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取user对象
        User user = (User) context.getBean("user");
        System.out.println(user);
    }
}

运行结果;

方式四：集合方式

原文地址：https://www.cnblogs.com/jumpkin1122/p/11623374.html