Java spring 通过注解方式创建对象的示例详解

<?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-4.3.xsd">
        <context:component-scan base-package="Bean.UserData"></context:component-scan>
</beans>

package Bean.UserData;

import org.springframework.stereotype.Component;

//最上面这个注解  就相当于之前xml中的bean声明  value就是当时的id class  就是当前类的路径
//类上的注解  value可以不写  不写用默认值  默认值就是类的名字
//但如果你的类名名首个字母是大写 默认值会将首字母变成小写
@Component(value = "userService")
public class user {
    public String toString(){
        return "我是user对象";
    }
}

import Bean.UserData.User;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

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

@Component(value="accountService")
public class AccountServiceImpl implements AccountService{
    public void saveAccount() {
        System.out.println("sevice方法被执行了....");
    }
}

<?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">
    <!--用于指定要扫描的包-->
    <context:component-scan base-package="com.hh">
    </context:component-scan>
</beans>

public class Client {
    public static void main(String[] args) {
        ApplicationContext context =
                new ClassPathXmlApplicationContext("bean.xml");
        AccountService service =
                context.getBean("accountService", AccountService.class);
        System.out.println(service);
    }
}