spring学习笔记之---IOC和DI

IOC和DI

（一）IOC

（1） 概念

IOC （Inverse of Control） 反转控制，就是将原本在程序中手动创建对象的控制权，交给spring框架管理。简单的说，就是创建对象控制权被反转到了spring框架

（2）实例

1.UserService.java

package service;

public interface UserService {
    public void getAa();
}

2.UserServiceImpl.java

package service;

public class UserServiceImpl implements UserService{

    @Override

    public void getAa() {

        System.out.println("aaaaaaaaaaa");

    }

}

3.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">

   <!--UserService将创建权交给spring-->

<bean id="userService" class="service.UserServiceImpl"></bean>

</beans>

4.UserTest.java

package Test;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import service.UserService;

import service.UserServiceImpl;

public class UserTest {

    @Test

    public void one(){

        //创建spring工厂

        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");

        //通过工厂获得类

        UserService userService=(UserService)applicationContext.getBean("userService");

        //通过类调用方法

        userService.getAa();

    }
}

（二）DI

（1）概念

DI（Dependency Injection）依赖注入，就是在spring创建这个对象的过程中，将这个对象所依赖的属性注入进去

（2）实例

1.UserService.java

package service;

public interface UserService {

    public void getAa();

}

2.UserServiceImpl.java

package service;

public class UserServiceImpl implements UserService{

    //添加属性

    private String name;

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public void getAa() {

        System.out.println("aaaaaaaaaaa"+name);

    }

}

3.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">

<!--UserService将创建权交给spring-->

<bean id="userService" class="service.UserServiceImpl">

    <!--设置属性-->

    <property name="name" value="张三"/>

</bean>

</beans>

4.UserTest.java

package Test;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import service.UserService;

import service.UserServiceImpl;

public class UserTest {

    @Test

    public void one(){

        //创建spring工厂

        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");

        //通过工厂获得类

        UserService userService=(UserService)applicationContext.getBean("userService");

        //通过类调用方法

        userService.getAa();

    }

}