一、IOC（控制反轉）

二、DI（依賴注入）

DI Dependency Injection 依賴注入的概念，就是在Spring建立這個物件的過程中，將這個物件所依賴的屬性注入進去。

程式碼：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:p="http://www.springframework.org/schema/p"
       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的建立權交給了Spring -->
   <bean id="userService" class="com.imooc.ioc.demo1.UserServiceImpl">
        <property name="name" value="李四"/>
    </bean>

</beans>
 

package com.imooc.ioc.demo1;

/**
 * Created by jt on 2017/10/8.
 */
public interface UserService {

    public void sayHello();
}

package com.imooc.ioc.demo1;

/**
 * Created by jt on 2017/10/8.
 */
public class UserServiceImpl implements  UserService{

    // 新增屬性:
    private String name;

    public void sayHello() {
        System.out.println("Hello Spring" + name);
    }

    public String getName() {
        return name;
    }

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

package com.imooc.ioc.demo1;

import org.junit.Test;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.FileSystemResource;

/**
 * Created by jt
 */
public class SpringDemo1 {

    @Test
    /**
     * 傳統方式開發
     */
    public void demo1(){
        // UserService userService = new UserServiceImpl();
        UserServiceImpl userService = new UserServiceImpl();
        // 設定屬性:
        userService.setName("張三");
        userService.sayHello();
    }

    @Test
    /**
     * Spring的方式實現
     */
    public void demo2(){
    	// 建立Spring的工廠
    	ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    	// 通過工廠獲得類
    	UserService userService = (UserService)applicationContext.getBean("userService");

    	userService.sayHello();
    }
}