SPRing(3.2.3) - Beans(8): 基于 Annotation 的配置除了基于 xml 的配置外，Spring 也支持基于 Annotation 的配置。Spring 提供以下介个 Annotation 来标注 Spring Bean：@Component：标注一个普通的 Spring Bean@Controller：标注一个控制器组件类@Service：标注一个业务逻辑组件类@Repository：标注一个 DAO 组件类
基于 Annotation 配置的示例DAO 组件以@Repository 标注：
public interface UserDao { public User getUserByUsername(String username);}@Repository("userDao")public class UserDaoImpl implements UserDao { List<User> users = new ArrayList<User>(); public UserDaoImpl() { users.add(new User(1001, "huey", "123")); users.add(new User(1002, "tmac", "abc")); users.add(new User(1003, "suer", "xxx")); } public User getUserByUsername(String username) { for (User user : users) { if (username.equals(user.getUsername())) { return user; } } return null; }}
业务逻辑组件以@Service 标注：
public interface UserServ { public User queryUserByUsername(String username); }@Service("userServ")public class UserServImpl implements UserServ { @Resource(name="userDao") private UserDao userDao; public User queryUserByUsername(String username) { return userDao.getUserByUsername(username); }}
Spring 配置文件，无需配置 Bean，但须配置 <context:component-scan/>：
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" 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-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- 自动扫描指定包及其子包下的所有 Bean 类 --> <context:component-scan base-package="com.huey.dream" /></beans>
测试方法：
@Testpublic void testAnnotation() throws Exception { applicationContext appCtx = new ClassPathXmlApplicationContext("applicationContext.xml"); UserServ userServ = appCtx.getBean("userServ", UserServ.class); String username = "huey"; User user = userServ.queryUserByUsername(username); System.out.println(user);}