Spring框架对于Bean的管理详解

package com.qcby.testanno;
public interface UserService {
    public void hello();
}

package com.qcby.testanno;
import org.springframework.stereotype.Component;


@Controller(value="us")
public class UserServiceImpl implements UserService {
    public void hello() {
        System.out.println("使用注解，方便吧！");
    }
}

<?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: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">
    <!--开启注解扫描 com.qcby所有的包中的所有的类-->
    <context:component-scan base-package="com.qcby"/>
</beans>

package com.qcby.test;
import com.qcby.testanno.UserService;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Demo2 {
    @Test
    public void run1(){
        ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("ApplicationContextanno.xml");
        UserService us = (UserService) ac.getBean("us");
        us.hello();
    }
}

// 默认当前类名就是ID名称，首字母小写
@Component(value = "car")
// @Controller
// @Service(value = "c")
// @Repository(valu = "c")
public class Car {
    // 注解注入值，属性set方法是可以省略不写的。
    // 只有一个属性，属性的名称是value，value是可以省略不写的
    @Value("大奔2")
    private String cname;
    @Value(value = "400000")
    private Double money;
    // 也不用提供set方法
    // 按类型自动装配的注解，和id名称没有关系
    @Qualifier("person")
    @Autowired  //注意：（所引用的Car类里面必须要写：类声明@Component(value="person") ）
    // 注入引用数据类型：不需要写值，根据类型自动匹配
    //@Resource(name="person")  //是jdk提供，按照名称进行注入，只能在引用数据类型当中发使用
    private Person person;
    @Override
    public String toString() {
        return "Car{" +
                "cname='" + cname + '\'' +
                ", money=" + money +
                ", person=" + person +
                '}';
    }
}

@Component(value = "person")
public class Person {
    @Value("张三")
    private String pname;
    @Override
    public String toString() {
        return "Person{" +
                "pname='" + pname + '\'' +
                '}';
    }
}

@Test
public void run1(){
    // 工厂
    ApplicationContext ac = new
            ClassPathXmlApplicationContext("applicationContext.xml");
    // 获取对象
    Car car = (Car) ac.getBean("car");
    System.out.println(car);
}