一：DI基本概念
依赖注入(DI)，是spring容器实现的基础，在spring-core模块中实现的。所谓DI，就是指对象是被动接受依赖类而不是自己主动去找，换句话说就是指对象不是从容器中查找它依赖的类，而是在容器实例化对象的时候主动将它依赖的类注入给它。
DI作用：
di配合接口编程，的确可以减少层(web层) 和 业务层的耦合度.
二：DI配合接口编程案例
1.项目截图
2.基本代码
package com.cloud.inter;
public
interfaceChangeLetter {
public String change();
}
package com.cloud.inter;
public
classLowerLetter
implements ChangeLetter{
private String
str;
public String getStr() {
return
str;
}
public
void setStr(String str) {
this.str = str;
}
@Override
public String change() {
//
TODO Auto-generated method stub
return
str.toLowerCase();
}
}
package com.cloud.inter;
public
classUpperLetter
implements ChangeLetter{
private String
str;
public String getStr() {
return
str;
}
public
void setStr(String str) {
this.str = str;
}
@Override
public String change() {
//
TODO Auto-generated method stub
return
str.toUpperCase();
}
}
3.配置代码
<?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:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
<!--
在测试代码中任意切换这两种配置方法 -->
<!--
<beanid="changeLetter" class="com.cloud.inter.UpperLetter">
<propertyname="str">
<value>abcef</value>
</property>
</bean>
-->
<bean
id="changeLetter"class="com.cloud.inter.LowerLetter">
<property
name="str"
value="ABCDE"/>
</bean>
</beans>
4.测试代码
package com.cloud.inter;
importorg.springframework.context.ApplicationContext;
importorg.springframework.context.support.ClassPathXmlApplicationContext;
public class App1 {
/**
* @param args
*/
publicstatic void main(String[] args) {
//TODO Auto-generated method stub
ApplicationContextac=new ClassPathXmlApplicationContext("com/cloud/inter/beans.xml");
//获取不使用接口
//UpperLetterchangeLetter=(UpperLetter) ac.getBean("changeLetter");
//System.out.println(changeLetter.change());
//使用接口访问bean
ChangeLetterchangeLetter=(ChangeLetter) ac.getBean("changeLetter");
System.out.println(changeLetter.change());
}
}
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