10.@Component注解的使用

 

注解的作用：取代了配置xml的配置bean繁琐。

 

 

 

 

IUserService .java

package com.gyf.service;

import com.gyf.model.User;

public interface IUserService {

    public void add();

    public void add(User user);
}

 

UserServiceImpl.java

package com.gyf.service;

import com.gyf.dao.IUserDao;
import com.gyf.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;


@Service("myUserService")
public class UserServiceImpl implements IUserService {

    @Autowired //spring会自动注入userDao赋值
    private IUserDao userDao;

    @Override
    public void add(User user) {
        System.out.println("service 添加用户:" + user);
        //调用dao
        userDao.add(user);
    }

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public void add() {
        System.out.println("创建用户...." + name);
    }




    public UserServiceImpl() {
        System.out.println("UserServiceImpl（）调用了");
    }
}

 

UserAction.java

package com.gyf.web.action;

import com.gyf.model.User;
import com.gyf.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;

@Controller
public class UserAction{

    @Autowired//spring自动注入userService赋值
    @Qualifier("myUserService")//根据指定的id注入属性
    private IUserService userService;

    public void save(User user){
        System.out.println("action save方法 ");
        userService.add(user);
    }
}

 

 Lesson12.java

package com.gyf.test;

import com.gyf.model.User;
import com.gyf.service.IUserService;
import com.gyf.web.action.UserAction;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Lesson12 {

    @Test
    public void test1() throws Exception {

       //注解的使用
        //web开发流程 action -> service -> dao
        ApplicationContext context = new ClassPathXmlApplicationContext("beans12.xml");


        //获取action
        UserAction userAction =  context.getBean(UserAction.class);

        //添加用户
        User user = new User();
        user.setUsername("gyf");
        user.setPassword("1234");
        userAction.save(user);
    }
}

 

 

Lesson10.java

package com.gyf.test;

import com.gyf.model.Programmer;
import com.gyf.model.User;
import com.gyf.service.IUserService;
import com.gyf.service.UserServiceImpl;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Lesson10 {

    @Test
    public void test1() throws Exception {

        //注解来取代xml中bean的配置
        /**
         * 1.Spring默认情况下注解不生效，开启注解功能
         * 2.如何开启spring注解功能？
         *   在.xml中配置下面两行代码
         */
        ApplicationContext context = new ClassPathXmlApplicationContext("beans10.xml");

        /*
        1.如果@Component没配置id,通过类型获取
        IUserService service = (IUserService) context.getBean(IUserServiceImpl.class);
        2.这个类型可以是接口，还可以是实现类
         */
        IUserService service = (IUserService) context.getBean(IUserService.class);

        //如果@Component("userService),配置了id，就可以通过id来获取
        //IUserService service = (IUserService) context.getBean("userService");


        User user = new User();
        user.setUsername("gyf");

        service.add(user);
    }
}

 

 

 

bean10.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--xmlns xml namespace:xml命名空间-->
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p ="http://www.springframework.org/schema/p"
       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">
    <!--1.在类中声明@Component 相当于配置了
        <bean class="com.gyf.service.UserServiceImpl"></bean>
    -->
    <!--<bean id="userService" class="com.gyf.service.UserServiceImpl"></bean>-->
    <!-- 开启注解-->
    <context:annotation-config/>

    <!-- 注解的位置-->
    <context:component-scan base-package="com.gyf"/>

</beans>