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1 项目结构如下
这里,业务层的UserService将引用dao层的UserDao组件
2 具体代码如下
//UserDao接口
package com.fhzheng.demo.dao;
public interface UserDao {
public String getUserById(Integer id);
}
//UserDao实现
package com.fhzheng.demo.dao.impl;
import com.fhzheng.demo.dao.UserDao;
public class UserDaoImpl implements UserDao {
@Override
public String getUserById(Integer id) {
String user="这是一个用户信息,他的编号是"+id;
return user;
}
}
//UserService接口
package com.fhzheng.demo.service;
public interface UserService {
public String getUserById(Integer id);
}
//UserService实现
package com.fhzheng.demo.service.impl;
import com.fhzheng.demo.dao.UserDao;
import com.fhzheng.demo.service.UserService;
public class UserServiceImpl implements UserService {
private UserDao userDao;
public UserDao getUserDao() {
return userDao;
}
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
@Override
public String getUserById(Integer id) {
String user = userDao.getUserById(id);
return user;
}
}
//在Spring配置文件中注册相应的组件,并完成组件之间的依赖注入
<?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">
<!-- 注册 Hello 组件,并完成属性的赋值 -->
<bean id="hello" class="com.fhzheng.demo.bean.Hello" >
<property name="name" value="fhzheng"></property>
<property name="age" value="30"></property>
</bean>
<!-- 注册 userDao 接口组件和 userService 接口组件,并完成依赖注入 -->
<bean id="userDao" class="com.fhzheng.demo.dao.impl.UserDaoImpl"></bean>
<bean id="userService" class="com.fhzheng.demo.service.impl.UserServiceImpl">
<property name="userDao" ref="userDao"></property>
</bean>
</beans>
//跑Junit测试
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringIocApplicationTests {
private ApplicationContext context;
@Before
public void testBefore() {
context = new ClassPathXmlApplicationContext("classpath:/applicationContext.xml");
}
@Test
public void testSpringIOCDaoAndService() {
// 业务,查看用户信息
UserService userService = context.getBean(UserService.class);
String user = userService.getUserById(55);
System.out.println("用户信息是:"+user);
}