Spring (3.2.3), spring3.2.3

Spring (3.2.3), spring3.2.3

In addition to XML-based configuration, Spring also supports Annotation-based configuration. Spring provides the following Annotation to mark Spring beans:
@ Component: Mark a common Spring Bean
@ Controller: Mark A Controller component class
@ Service: Mark a business logic component class
@ Repository: Mark a DAO component class

 

Example of Annotation-Based Configuration

The DAO component is marked with @ Repository:

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;    }}

The business logic component is marked with @ Service:

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);    }}

The Spring configuration file does not require Bean configuration, but you must configure <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.xsdHttp://www.springframework.org/schema/context        Http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <! -- Automatically scans all Bean classes in the specified package and its sub-packages --><Context: component-scan base-package = "com. huey. dream"/></Beans>

Test method:

@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);}