package com.ahd.utils;

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

public class ApplicationContextUtil {
    static ApplicationContext ac=null;
    
    //创建私有无参构造方法
    private ApplicationContextUtil(){}
    
    static{
        ac=new ClassPathXmlApplicationContext("beans.xml");
    }
    public static ApplicationContext getApplicationContext(){
        return ac;

    }
}

2.spring开发提倡接口编程,配合di技术可以层与层的解耦,通过接口,   配置文件可以很容易把一个类信息改变成另一个类

3.思路

　　1).创建一个接口ValidateUser

　　2).两个类实现接口,

　　3).把对象配置到spring容器中

　　4).使用(通过接口来获取getBean获得的对象)

4.具体实现

　　接口ValidateUser　　　

package com.ahd.service;

public interface ValidateUser {
    public void check();
}

　　实现接口的类CheckUser1

package com.ahd.serviceImpl;

import com.ahd.service.ValidateUser;

public class CheckUser1 implements ValidateUser{
    private String username;
    private String password;
     
    @Override
    public void check() {
        System.out.println(username+password);
        System.out.println("通过xml验证成功");
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

　　实现接口的类CheckUser2

package com.ahd.serviceImpl;

import com.ahd.service.ValidateUser;

public class CheckUser2 implements ValidateUser{
    private String username;
    private String password;
     
    @Override
    public void check() {
        System.out.println(username+password);
        System.out.println("通过数据库验证成功");
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    } 
}

　　配置文件beans.xml,配置的两个bean对象可以相互替换(注释的和没有注释的)

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/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
                http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
                http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
     在容器文件中配置数据源(bean/entity/service/dao/pojo) -->
     bean元素的作用是当spring框架加载的时候,spring会自动为bean类 UserService类的属性设置值  id就是创建对象的对象名 -->
         
    
        
            爱华顿g
        
        
    
 -->
    bean id="validateUser" class="com.ahd.serviceImpl.CheckUser2">
        property name="username">
            value>爱华顿gvalue>
        property>
        property name="password" value="123456">property>
    bean>
    
beans>

　　测试代码Test

package com.ahd.test;

import static org.junit.Assert.*;

import com.ahd.service.ValidateUser;
import com.ahd.utils.ApplicationContextUtil;

public class Test {

    @org.junit.Test
    public void test() {
        //使用接口实现
        ValidateUser vu=(ValidateUser) ApplicationContextUtil.getApplicationContext().getBean("validateUser");
        vu.check();
    }

}