spring注解入门案例

spring注解入门案例

• 基于maven项目

1、准备jar包

  <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.2.6.RELEASE</version>
    </dependency>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>5.2.6.RELEASE</version>
</dependency>

2、编写实体类

package com.yl.bean;

import java.io.Serializable;

/**
 * 用户实体类
 */
public class User implements Serializable {
    private Integer id;
    private String username;
    private String password;

    public User() {
    }

    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

3、编写业务层

• 业务层接口

package com.yl.service;

/**
 * 用户业务层接口
 */
public interface IUserService {

    /**
     * 查询用户
     */
    public void queryUser();

}

• 业务层实现类

package com.yl.service.impl;

import com.yl.dao.IUserDao;
import com.yl.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

/**
 * 用户业务层接口实现类
 */
@Service("userService")//使用注解创建业务层bean对象
public class IUserServiceImpl implements IUserService {
    @Resource(name = "userDao")//使用注解注入指定bean对象
    private IUserDao iUserDao;//用户持久层对象

    /**
     * 查询用户
     */
    @Override
    public void queryUser() {
        iUserDao.queryUser();
    }
}

4、编写持久层

• 持久层接口

package com.yl.dao;

/**
 * 用户持久层接口
 */
public interface IUserDao {

    /**
     * 查询用户
     */
    public void queryUser();

}

• 持久层实现类

package com.yl.dao.impl;

import com.yl.dao.IUserDao;
import org.springframework.stereotype.Repository;

/**
 * 用户持久层接口实现类
 */
@Repository("userDao")//使用注解创建持久层bean对象
public class IUserDaoImpl implements IUserDao {

    /**
     * 查询用户
     */
    @Override
    public void queryUser() {
        System.out.println("查询成功");
    }
}

5、配置文件

• 配置文件放在资源目录（根目录）下

<?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">


    <!--指定spring要扫描的包-->
    <context:component-scan base-package="com.yl"></context:component-scan>

</beans>

6、模拟表现层（测试）

package com.yl.ui;

import com.yl.service.IUserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 表现层
 */
public class UI {

    public static void main(String[] args) {
        //获取spring容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("bean.xml");
        //获取业务层对象
        IUserService userService= (IUserService) applicationContext.getBean("userService");
        //查询用户
        userService.queryUser();
    }

}