@component使用案例

全栈程序员-站长 • 2021年7月19日下午4:00 • 未分类 • 阅读 71

@component的作用是将一个java类加入到spring容器中管理，省去了<bean id=”” class=””>这句配置，取而代之的是<context component-scan base-package=”包名” />，负责扫描改包下的所有包名。

案例：

<?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:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans   
  http://www.springframework.org/schema/beans/spring-beans.xsd  
  http://www.springframework.org/schema/aop   
  http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
  http://www.springframework.org/schema/tx   
  http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
  http://www.springframework.org/schema/context   
  http://www.springframework.org/schema/context/spring-context-4.0.xsd
  http://www.springframework.org/schema/util   
  http://www.springframework.org/schema/util/spring-util-4.0.xsd
  ">
      	
     <context:component-scan base-package="com.aa"></context:component-scan>
      		
</beans>

package com.aa;

import org.springframework.stereotype.Component;
import com.introduce.Model.User2;
@Component("impl")
public class UserDaoImpl {
	public User2 getUser2() {
		
		return null;
	}
	public User2 getUser2(String name) {
		User2 user2=new User2();
		user2.setAge(22);
		System.out.println(name+"s1");
		return  user2;
	}
	
	public void aa(){
		System.out.println("bbbbb");
	}
}

import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.aa.UserDaoImpl;

public class Test4 {
	@Autowired
	private UserDaoImpl userDaoImpl;
	@Test
	public void test() {
		//启动spring容器，因为是测试类，所以要使用applicationContext.如果是tomcat启动就不用。
		ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext5.xml");
		userDaoImpl=(UserDaoImpl) ac.getBean("impl");
		userDaoImpl.aa();
	}

}