day38 16-Spring的Bean的装配：注解的方式

Posted 2020-09-11 绿茵好莱坞

Struts 2和hibernate也使用注解,但是使用注解在以后的开发中应用不多。但是可以说在整合的时候如何进行注解开发。在Spring中,注解必须会玩。

package cn.itcast.spring3.demo1;

import org.springframework.stereotype.Component;

/**
 * 注解的方式装配Bean.
 * @author zhongzh
 *
 */
//在Spring配置文件中<bean id="userService" class="cn.itcast.demo1.UserService">
//其实也需要核心配置文件,只不过不是用来装配bean了,你得告诉Spring需要去哪些包下面去扫描.它得扫描到这些注解才行.它得去哪里扫描你得告诉人家才行
//@Component(value="userService")
@Component("userService")
public class UserService {
    
     public void sayHello(){
         
         System.out.println("Hello Spring Annotation.....");
     }
}

<?xml version="1.0" encoding="UTF-8"?>
<!-- 基于注解的开发需要引入context命名空间。它就是用来配置去扫描哪些包的. -->
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:p="http://www.springframework.org/schema/p"
       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">
<context:annotation-config></context:annotation-config><!-- XML和注解混搭的时候用的 -->
<!-- 告诉Spring你要扫描哪些包下的东西 -->
<!--  
<context:component-scan base-package="cn.itcast.spring3.demo1">

-->
<context:component-scan base-package="cn.itcast.spring3.demo1"><!-- 纯注解用扫描的就行 -->











</context:component-scan>



</beans>

package cn.itcast.spring3.demo1;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

//注解的方式:都是将类装载到容器中.
public class SpringTest1 {
   @Test
   public void demo1(){
       
      ApplicationContext  applicationContext  = new ClassPathXmlApplicationContext("applicationContext.xml");
      UserService userService = (UserService) applicationContext.getBean("userService");
      userService.sayHello();
   }
    
    
}