spring框架4：bean的装配2（spring的核心功能）

2.基于注解的bean装配

一般会通过注解完成bean的配置，相对比较简单，减少工作量。

新建模块springBean2

说明：目录结构如上所示，实现的先后顺序如下：

1)   pom.xml

2)   User

3)   UserDaoImp

4)   UserService

5)   UserController

6)   applicationContext.xml

7)   SpringTest

pom.xml

<dependencies>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.3.20</version>
  </dependency>

  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13</version>
  </dependency>
</dependencies>

User

package com.scitc.domain;

public class User {
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    private String id;
    private String name;
    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                '}';
    }
}

UserDaoImp

package com.scitc.dao;

import com.scitc.domain.User;
import org.springframework.stereotype.Repository;

@Repository
public class UserDaoImp {
    public void addUser(User user){
        System.out.println("3--dao层被调用");
        System.out.println("4--完成数据库操作，添加一个用户，用户id:"+user.getId()+"姓名："+user.getName());
    }
}

UserService

package com.scitc.service;

import com.scitc.dao.UserDaoImp;
import com.scitc.domain.User;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
@Service
public class UserService {
    @Resource
    public UserDaoImp userDao;
    public void addUser(User user){
        userDao.addUser(user);
    }
}

UserController

package com.scitc.controller;

import com.scitc.domain.User;
import com.scitc.service.UserService;
import org.springframework.stereotype.Controller;

import javax.annotation.Resource;

@Controller
//说明（重点理解）
//@Controller注释替代了xml配置 <beaen id="userController" class="com.scitc.controller.UserController"/>
//@Resource释替代了xml配置 <property name="userService" ref="userService"/>
public class UserController {
    @Resource
    public UserService userService;
    public void addUser(User user){
        System.out.println("2--service层被调用");
        userService.addUser(user);
    }
}

applicationContext.xml

<?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">

<!--使用context命名空间，配置spring对指定包com下所有类进行扫描，并进行注解解析-->
<context:component-scan base-package="com"/>

</beans>

 

说明：注意引入顶部的3行context相关的命名约束

SpringTest

package com.scitc;

import com.scitc.controller.UserController;
import com.scitc.domain.User;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringTest {
    @Test
    public void addUser(){
        User user = new User();
        user.setId("01");
        user.setName("张三");

        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserController userController = (UserController)context.getBean("userController");
        //输出Setter属性注入值
        System.out.println("1--controller层被调用");
        userController.addUser(user);
    }
}

运行