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 = newClassPathXmlApplicationContext("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/beanshttp://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 {@Overridepublic 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;}@Overridepublic 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。