Spring HelloWorld annotation

工程的目录结构以及所需的jar包如下：

 

1.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"
     xmlns:context="http://www.springframework.org/schema/context"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context.xsd">

   <!-- The implicitly registered post-processors include AutowiredAnnotationBeanPostProcessor, CommonAnnotationBeanPostProcessor,PersistenceAnnotationBeanPostProcessor, as well as the aforementioned RequiredAnnotationBeanPostProcessor.-->
   <context:annotation-config/>
   
   <bean name="userDao1" class="com.bjsxt.dao.impl.UserDAOImpl"></bean>
   <bean name="userDao2" class="com.bjsxt.dao.impl.UserDAOImpl"></bean>
   <bean name="userService" class="com.bjsxt.service.UserService"></bean>

</beans>

2.接口UserDao

package com.bjsxt.dao;
import com.bjsxt.model.User;
public interface UserDAO {
	public void save(User user);
}

3.接口的实现UserDaoImpl

package com.bjsxt.dao.impl;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

public class UserDAOImpl implements UserDAO {

	public void save(User user) {
        System.out.println("test--------"+user.getUsername());
		System.out.println("user saved!");
	}
}

4.编写数据传输User类

package com.bjsxt.model;

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;
	}
}

5.UserService

package com.bjsxt.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

public class UserService {
	private UserDAO userDAO;  
	public void add(User user) {
		userDAO.save(user);
	}
	
	
	public UserDAO getUserDAO() {
		return userDAO;
	}
	
  /*首先按名称来注入，由于没有名为"userDAO"的bean。所以采用类型来注入，但是com.bjsxt.dao.UserDAO类型的bean有2个，所以会报错。
   *处理：搭配@Qualifier来使用，指定注入userDao1，userDao2中那个bean
   */
	@Autowired  
	@Qualifier("userDao2") //指定注入userDao2
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
}

6.编写测试类UserServiceTest

package com.bjsxt.service;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.bjsxt.model.User;

public class UserServiceTest {

	@Test
	public void testAdd() {
		/**ApplicationContext是建立在BeanFactory之上的，BeanFactory它只是完成了Bean工厂的一些功能，像Bean的声明周期它都处理不了。而ApplicationContext除了能完成BeanFactory所有的功能之外，还能够完成 一些其他的附加的功能，比如说bean的声明的周期。
		*/
		ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");

		UserService service = (UserService)ctx.getBean("userService");

		User u = new User();
		u.setUsername("zhangsan");
		u.setPassword("gaoweigang");
		service.add(u);
	}

}