注解@Component

需求：

bean对象本身，移出beans.xml配置文件，也通过注解进行。

创建文件：

同注入对象章节。
1.创建com.tutorialspoint包
2.创建HelloWorld类
3.创建MainAPP主类（void main）
4.创建Beans.xml
5.ModelTest类

代码：

Beans

删掉之前留下的代码，新增<context:component-scan base-package="com.tutorialspoint"/>
其作用是告诉Spring，bean都放在com.tutorialspoint这个包下

<?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:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
   http://www.springframework.org/schema/beans 
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop 
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx 
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context      
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <context:component-scan base-package="com.tutorialspoint"/>
</beans>

HelloWorld.java

为HelloWorld类加上@Component注解，即表明此类是bean，name为helloworld。

package com.tutorialspoint;
import org.springframework.stereotype.Component;
@Component("helloworld")
public class HelloWorld {
    private String message = "helloworld";
    public void setMessage(String message){
        this.message  = message;
    }
    public void getMessage(){
        System.out.println("Your Message : " + message);
    }
}

ModelTest.java

为ModelTest类加上@Component注解，即表明此类是bean，name为modeltest。
@Autowired保留。

package com.tutorialspoint;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component("modeltest")
public class ModelTest {
    private String str = "modeltest";
    @Autowired
    private HelloWorld helloWorld;
    public void setStr(String string){
        this.str  = string;
    }
    public void getStr(){
        System.out.println("Your str : " + str);
    }
    public void setHelloWorld(HelloWorld helloworld){
        this.helloWorld  = helloworld;
    }
    public void getHelloWorld(){
        helloWorld.getMessage();
    }
}

MainApp.java

保留不变，和原来一样。

package com.tutorialspoint;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ApplicationContext context = 
                 new ClassPathXmlApplicationContext("Beans.xml");
          HelloWorld obj = (HelloWorld) context.getBean("helloworld");
          obj.getMessage();
          ModelTest model = (ModelTest) context.getBean("modeltest");
          model.getStr();
          model.getHelloWorld();
    }
}

运行结果：

要点：

@component一般用来配置