使用注解开发

（1）在spring4之后，要使用注解开发，必须要保证aop的包导入了

使用注解需要导入context约束，增加注解的支持！

精简版：

"1.0" encoding="UTF-8"?>
<beans xmlns="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
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
 
    <context:annotation-config/>
    
    
 
beans>

扩展版： 

"1.0" encoding="UTF-8"?>
<beans xmlns="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
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
 
    <context:annotation-config/>
 
    
    <context:component-scan base-package="com.gt.pojo"/>
 
 
beans>

（2）bean

 绿色的叶子表示放入组件当中！

 User

package com.gt.pojo;
 
import org.springframework.stereotype.Component;
 
//@Component 等价于
//@Component 组件
 
@Component
public class User {
 
    public String name = "山姆";
}

MyTest

import com.gt.pojo.User;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class MyTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //getBean括号里面的东西就是默认类的小写
        User user = context.getBean("user",User.class);
        System.out.println(user.name);
    }
}

（3）属性如何注入

• @Component 等价于
• @Component 就是组件
• @Value("shanmu2") 相当于在beans.xml中
   

package com.gt.pojo;
 
        import org.springframework.beans.factory.annotation.Value;
        import org.springframework.stereotype.Component;
 
//@Component 等价于
//@Component 组件
 
@Component
public class User {
 
    //@Value("shanmu2") 相当于在beans.xml中
 
    public String name;
    
    @Value("shanmu2")
    public void setName(String name) {
        this.name = name;
    }
}

/**
 * @Component 等价于
 *
 */
@Component
// @Scope("prototype") 这个等价于作用域
@Scope("prototype") 
public class User {
    /**
     * 相当于
     *     
     *         
     *     
     */
//    @Value("山姆02")
    public String name;
 
 
    @Value("shanmu02")
    public void setName(String name) {
        this.name = name;
    }
}

    <context:annotation-config/>
 
    
    <context:component-scan base-package="com.gt"/>