Spring配合接口实现解耦原理

一个简单的接口：

public interface ChangLetter {

public String change();

}

两个实现：

package com.pas.service;

import com.inter.ChangLetter;

public class LowLetter implements ChangLetter {

private String str;

@Override

public String change() {

// 大写-》小写

return str.toLowerCase();

}

public String getStr() {

return str;

}

public void setStr(String str) {

this.str = str;

}

}

package com.pas.service;

import com.inter.ChangLetter;

public class UpLetter implements ChangLetter {

private String str;

@Override

public String change() {

// 小写-》大写

return str.toUpperCase();

}

public String getStr() {

return str;

}

public void setStr(String str) {

this.str = str;

}

}

spring配置文件：

<?xml version="1.0" encoding="UTF-8"?>

<beans 'dtd'>

<!--<bean id="changeLetter" class="com.pas.service.UpLetter">

<property name="str" value="abcdefg" />

</bean> -->

<bean id="changeLetter" class="com.pas.service.LowLetter"> <property

name="str" value="ABCDEFG" /> </bean>

</beans>

使用模拟view：

public class Test {

public static void main(String[] args) {

ApplicationContext ac= new ClassPathXmlApplicationContext("com/pas/service/beans.xml");

ChangLetter change= (ChangLetter) ac.getBean("changeLetter");

System.out.println(change.change());

}

}

重新配置Spring配置文件 代码无需更改