Spring的核心概念理解案列

IDEA开发的简单“登陆成功”小项目

IDEA项目结构：

每一部分代码和相应的解读：

com.itTony文件下有dao（实体）层，service（服务）层，编写的2个类（HelloSpring和TestSpring）和applicationContext.xml

package com.itTony;

public class HelloSpring {
    private String userName;

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public void show() {
        System.out.println(userName + ":欢迎来到Spring");
    }
}

package com.itTony;

import com.itTony.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestSpring {
    public static void main(String[] args) {
        //加载applicationContext.xml配置
        ApplicationContext applicationContext = new
                ClassPathXmlApplicationContext("applicationContext.xml");

        //获取配置中的UserService实例
        UserService userService = (UserService)
                applicationContext.getBean("userService");
        boolean flag = userService.login("张三", "123");
        if (flag) {
            System.out.println("登录成功");
        } else {
            System.out.println("登录失败");
        }
    }
}

<?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">
    <!-- 将指定类配置给Spring，让Spring创建HelloSpring对象的实例 -->
    <bean id="helloSpring" class="com.itTony.HelloSpring">
        <!--为userName属性赋值-->
        <property name="userName" value="张三"></property>
    </bean>
    <bean id="userDao" class="com.itTony.dao.impl.UserDaoImpl"></bean>
    <bean id="userService" class="com.itTony.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"></property>
    </bean>
</beans>

在dao层写了个接口（UserDao），对用户名和密码进行bool值的判断。

package com.itTony.dao;

public interface UserDao {
    boolean login(String username, String password);
}

在dao目录下写了个impl包，UserDaoImpl实现了UserDao。

package com.itTony.dao.impl;

import com.itTony.dao.UserDao;

public class UserDaoImpl implements UserDao {
    @Override
    public boolean login(String name, String password) {
        return name.equals("张三") && password.equals("123");
    }
}

service层与dao层的结构类似。

package com.itTony.service;

public interface UserService {
    boolean login(String username, String password);
}

package com.itTony.service.impl;

import com.itTony.dao.UserDao;
import com.itTony.service.UserService;

public class UserServiceImpl implements UserService {
    private UserDao userDao;

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public boolean login(String name, String password) {
        return userDao.login(name, password);
    }
}

测试结果：因为用户名和密码匹配成功。所以显示登录成功。