spring通过注解配置bean

最新推荐文章于 2025-05-25 18:51:26 发布

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本文详细介绍了Spring框架中@Component、@Controller、@Service及@Repository等注解的使用方法，并阐述了这些注解在不同层（如Controller层、Service层、Repository层）的应用方式以及如何通过这些注解将类注册为Spring容器中的bean。

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注意点

@Component是一个基本注解,一个受spring管理组件,如果@Repository,@Controller,@Service,三个注解都没有给value命名(—不给值@Controller,给值得为@Controller(“UserController”)—)那么,必须要有@Component注解例如:
没有@Component就无法进行识别
Component层

package com.wenhe.annotation;
import org.springframework.stereotype.Component;

@Component
public class TestObject {

}

Controller层

package com.wenhe.controller;

import org.springframework.stereotype.Controller;

@Controller
public class UserController {
	
	public void execute(){
		System.out.println("UserController execute...");
	}
}

service层

package com.wenhe.service;

import org.springframework.stereotype.Service;

@Service
public class UserService {
	
	public void add(){
		System.out.println("userservice  add....");
	}
	
}

@Repository层Dao

package com.wenhe.dao;

import org.springframework.stereotype.Repository;

@Repository("UserRspository")
public class UserRspositoryImpl implements UserRspository {

	@Override
	public void save() {
		System.out.println("UserRspositoryImpl   save(111");
	}

}

测试结果:
.getBean(“userController”);中的命名必须是该类的首字母小写其他不变,如下:

ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationcontext.xml");
		
		TestObject to = (TestObject)ctx.getBean("testObject");
		System.out.println(to);
		
		UserController usercontroller = (UserController)ctx.getBean("userController");
		System.out.println(usercontroller);
		
		
		UserService userService = (UserService)ctx.getBean("userService");
		System.out.println(userService);
		
		UserRspositoryImpl UserRspository = (UserRspositoryImpl)ctx.getBean("userRspositoryImpl");
		System.out.println(UserRspository);

不需要@Component的则如下:

需要每一层的注解都要给定命名

Service

package com.wenhe.service;

import org.springframework.stereotype.Service;

@Service("UserService")//要自定义命名
public class UserService {
	
	public void add(){
		System.out.println("userservice  add....");
	}
	
}

Controller

package com.wenhe.controller;

import org.springframework.stereotype.Controller;

@Controller("UserController")
public class UserController {
	
	public void execute(){
		System.out.println("UserController execute...");
	}
}

Repository

package com.wenhe.dao;

import org.springframework.stereotype.Repository;

@Repository("UserRspository")
public class UserRspositoryImpl implements UserRspository {

	@Override
	public void save() {
		System.out.println("UserRspositoryImpl   save(111");
	}

}

.getBean(“UserController”);必须为自己定义的名

	ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationcontext.xml");
		
		
		UserController usercontroller = (UserController)ctx.getBean("UserController");
		System.out.println(usercontroller);
		
		
		UserService userService = (UserService)ctx.getBean("UserService");
		System.out.println(userService);
		
		UserRspositoryImpl UserRspository = (UserRspositoryImpl)ctx.getBean("UserRspository");
		System.out.println(UserRspository);

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