五、Spring容器組建注解@Component和Resouces實現完全注解配置 · Spring入門系列

@Resource和@Component實現零XML配置 1、@Resource的注解： @Resource是J2EE的注解。意思是說在容器里面找相應的資源。也可以通過name屬性指定它name的資源。可以注解到field或者setter上面 ~~~ public class UserAction { private UserService userService; @Resource(name="userService") public void setUserService(UserService userService) { this.userService = userService; } public void addUser(){ userService.HelloWorld(); } } ~~~ 2、@Component @Component和<context:component-scan base-package="com.spring"></context:component-scan>配合實現無XML配置，只通過注解配置及可將類放入資源容器中。案例解析： 1、 xml文件：配置容器資源掃描的包 ~~~ <?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-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/>  <context:component-scan base-package="com.spring"></context:component-scan> </beans> ~~~ 2、 Java文件：標注資源的注解@Component。括號里面指定的是存入容器的name屬性為userService 那么將來我們拿的時候則getBean(“userService”)即可。如果我們不指定userService它默認存入容器bean的key為userServiceImpl這樣就可以得到一個裝有UserServiceImpl對象的容器 ~~~ package com.spring.service; import org.springframework.stereotype.Component; import com.spring.dao.UserDao; @Component("userService") public class UserServiceImpl implements UserService{ private UserDao userDao; public void init(){ System.out.println("init"); } public void destory(){ System.out.println("destory"); } public UserDao getUserDao() { return userDao; } public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void HelloWorld(){ System.out.println("helloworld"); } } ~~~ 通過@Resource將資源注入進來因為上文已經配置了容器里面的資源。所以我這里將資源通過@Resource注解將資源注入到相關的屬性。請看代碼： ~~~ @Component("userAction") public class UserAction { private UserService userService; //它會將beans的xml文件配置加入進去 //也可以使用name屬性指定byName的指定 @Resource(name="userService") public void setUserService(UserService userService) { this.userService = userService; } public void addUser(){ userService.HelloWorld(); } } ~~~ 測試實現：通過上文配置的userAction案例來得到這個對象然后調用它里面的方法，因為上文通過了@ Component注解將UserAction的對象配置到了容器里面。所以獲得容器之后就可以用這種方法getbean即可 ~~~ @Test public void test01(){ BeanFactory applicationContext = new ClassPathXmlApplicationContext("beans.xml"); UserAction user = (UserAction) applicationContext.getBean("userAction"); user.addUser(); } @Scope和@PostConstruct、@PreDestroy ~~~ 很簡單就相當于前面講到的作用于和initmethod和destorymethod請看下面代碼。不再多說： ~~~ @Scope("Singleton") @Component("userService") public class UserServiceImpl implements UserService{ private UserDao userDao; @PostConstruct public void init(){ System.out.println("init"); } @PreDestroy public void destory(){ System.out.println("destory"); } public UserDao getUserDao() { return userDao; } public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void HelloWorld(){ System.out.println("helloworld"); } } ~~~