Spring_IOC_单例模式和多例模式

1.目录结构

2.User

package com.cloud.spring.model;

/**
 * @author cloud
 * @data 2016年5月13日
 * @version 1.0
 * @description:普通的JavaBean
 */
public class User {
    private String username;
    private String password;
    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;
    }
}

 

3.UserDAO

package com.cloud.spring.dao;

import com.cloud.spring.model.User;

/**
 * @author cloud
 * @data 2016年5月13日
 * @version 1.0
 * @description:定义接口，定义规范，必须实现save方法
 */
public interface UserDAO {
    public void save(User user);
}

 

4.UserDAOImpl

package com.cloud.spring.dao.imp;

import com.cloud.spring.dao.UserDAO;
import com.cloud.spring.model.User;

/**
 * 
 * @author cloud
 * @data 2016年5月13日
 * @version 1.0
 * @description:实现接口，重写方法
 */
public class UserDAOImpl implements UserDAO {

    private int daoId = 0;
    
    public void save(User user) {
        System.out.println("user saved!");
    }
    
    public int getDaoId() {
        return daoId;
    }

    public void setDaoId(int daoId) {
        this.daoId = daoId;
    }

    /*@Override
    public String toString(){
        return "daoId="+daoId;
    }*/

}

 

5.UserService

package com.cloud.spring.service;

import com.cloud.spring.dao.UserDAO;
import com.cloud.spring.model.User;

/**
 * 
 * @author cloud
 * @data 2016年5月13日
 * @version 1.0
 * @description:真正的业务处理
 */
public class UserService {
    
    private UserDAO userDAO;

    public void add(User user) {
        userDAO.save(user);
    }

    public UserDAO getUserDAO() {
        return userDAO;
    }

    public void setUserDAO(UserDAO userDAO) {
        this.userDAO = userDAO;
    }
}

 

6.TestSpring

package com.cloud.spring.test;

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

import com.cloud.spring.dao.UserDAO;
import com.cloud.spring.service.UserService;

public class TestSpring {
    public static void main(String[] args) {
        try {
            ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
            
            //如果bean配置的是单例模式singleton，那么得到的两个bean是同一个bean
            //如果bean配置的是多例模式prototype，那么得到的两个bean是不同的bean
            UserDAO userDAO = (UserDAO) ctx.getBean("userDAO");
            System.out.println(userDAO);
            
            UserDAO userDAO2 = (UserDAO) ctx.getBean("userDAO");
            System.out.println(userDAO2);
        } catch (BeansException e) {
            e.printStackTrace();
        }
    }
}

 

7.beans.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 中有个实例域UserDAO，需要将UserDAOImp的一个实例注入到UserDAO中去 -->
    <!-- 如果定义scope是单例模式，那么每次使用的bean都是同一个 -->
    <!-- scope="singleton"为单例模式，scope="prototype"为多例模式，默认是 singleton-->
    <bean id="userDAO" class="com.cloud.spring.dao.imp.UserDAOImpl" scope="singleton"/>
    
    <bean id="userService" class="com.cloud.spring.service.UserService" >
        <property name="userDAO" ref="userDAO" />
    </bean>
</beans>