【Spring】@Component组件

 大前提：

 添加了相关的约束文件以及注解支持

"1.0" encoding="UTF-8"?>
"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.xsd
             http://www.springframework.org/schema/context
             http://www.springframework.org/schema/context/spring-context.xsd">
 
 
    
 
 
 
 

package org.example.eneity;
 
 
import org.springframework.stereotype.Component;
 
@Component
public class User {
    public String name="张三";
 
}

public String name=" 张三 ”可以如下这么写

package org.example.entity;
 
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
 
@Component
public class User {
    @Value("张三")
    public String name;
 
}

 

@Componen注解的作用相当于创建了一个bean

@Component =  

 beans.xml

package="org.example.entity"/>

它的作用是：指定扫描这个包，在这个包下的注解会生效 

 

测试

 
public class Test10 {
    public static void main(String[] args) {
    ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
    User user=(User) context.getBean("user");
        System.out.println(user.name);
    }
}