mapper映射

springboot整合mybatis完整示例, mapper注解方式和xml配置文件方式实现(我们要优雅地编程)

一、注解方式

1. pom

    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.0.0</version>
    </dependency>
     <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
	<!--lombok-->
	<dependency>
		<groupId>org.projectlombok</groupId>
		<artifactId>lombok</artifactId>
		<version>1.16.10</version>
	</dependency>

说明: springboot版本: 2.1.5.RELEASE

1. application.properties

# mysql
spring.datasource.url=jdbc:mysql://212.64.xxx.xxx:3306/test?autoR&useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true
spring.datasource.username=xxx
spring.datasource.password=xxx
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

3.在启动类中添加对 mapper 包扫描@MapperScan

package com.wangzaiplus.test;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;

@SpringBootApplication
@MapperScan("com.wangzaiplus.test.mapper")
public class TestApplication {

	public static void main(String[] args) {
		SpringApplication.run(TestApplication.class, args);
	}

	/**
	 * 跨域
	 * @return
	 */
	@Bean
	public CorsFilter corsFilter() {
		final UrlBasedCorsConfigurationSource urlBasedCorsConfigurationSource = new UrlBasedCorsConfigurationSource();
		final CorsConfiguration corsConfiguration = new CorsConfiguration();
		corsConfiguration.setAllowCredentials(true);
		corsConfiguration.addAllowedOrigin("*");
		corsConfiguration.addAllowedHeader("*");
		corsConfiguration.addAllowedMethod("*");
		urlBasedCorsConfigurationSource.registerCorsConfiguration("/**", corsConfiguration);
		return new CorsFilter(urlBasedCorsConfigurationSource);
	}

}

说明: springboot项目添加corsFilter解决跨域问题

也可以直接在 Mapper 类上面添加注解@Mapper

1. mapper

package com.wangzaiplus.test.mapper;

import com.wangzaiplus.test.pojo.User;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.type.JdbcType;

import java.util.List;

public interface UserMapper {

    @Select("select * from user")
    @Results({
            @Result(property = "username", column = "username", jdbcType = JdbcType.VARCHAR),
            @Result(property = "password", column = "password")
    })
    List<User> selectAll();

    @Select("select * from user where id = #{id}")
    @Results({
            @Result(property = "username", column = "username", jdbcType = JdbcType.VARCHAR),
            @Result(property = "password", column = "password")
    })
    User selectOne(Integer id);

    @Insert("insert into user(username, password) values(#{username}, #{password})")
    void insert(User user);

    @Update("update user set username=#{username}, password=#{password} where id = #{id}")
    void update(User user);

    @Delete("delete from user where id = #{id}")
    void delete(Integer id);

}

1. controller

package com.wangzaiplus.test.controller;

import com.wangzaiplus.test.pojo.User;
import com.wangzaiplus.test.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("users")
    public String getAll() {
        List<User> users = userService.getAll();
        return users.toString();
    }

    @GetMapping("{id}")
    public String getOne(@PathVariable Integer id) {
        User user = userService.getOne(id);
        return user + "";
    }

    @PostMapping
    public String add(User user) {
        userService.add(user);
        return "nice";
    }

    @PutMapping
    public String update(User user) {
        userService.update(user);
        return "nice";
    }

    @DeleteMapping("{id}")
    public String delete(@PathVariable Integer id) {
        userService.delete(id);
        return "nice";
    }

}

说明: restful接口风格

1. service

package com.wangzaiplus.test.service;

import com.wangzaiplus.test.pojo.User;

import java.util.List;

public interface UserService {

    List<User> getAll();

    User getOne(Integer id);

    void add(User user);

    void update(User user);

    void delete(Integer id);

}

1. impl

package com.wangzaiplus.test.service.impl;

import com.wangzaiplus.test.mapper.UserMapper;
import com.wangzaiplus.test.pojo.User;
import com.wangzaiplus.test.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public List<User> getAll() {
        return userMapper.selectAll();
    }

    @Override
    public User getOne(Integer id) {
        return userMapper.selectOne(id);
    }

    @Override
    public void add(User user) {
        userMapper.insert(user);
    }

    @Override
    public void update(User user) {
        userMapper.update(user);
    }

    @Override
    public void delete(Integer id) {
        userMapper.delete(id);
    }

}

说明: 仅供示例, 逻辑严谨性暂不考虑

1. pojo

package com.wangzaiplus.test.pojo;

import lombok.Data;

@Data
public class User {

    private Integer id;
    private String username;
    private String password;

}

说明: @Data lombok

9.sql

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(100) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
  `password` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  UNIQUE KEY `unq_username` (`username`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

1. 接口请求

• add

• update

• delete

• getOne

• getAll

说明: 截图请求参数id与数据库id不对应问题, 这是由于我接口文档默认值设为1或2的, 请求成功后接口管理工具自动刷新显示默认值id=1了, 所以看着好像不对, 实际没问题

以上代码均通过测试

二、xml方式

1. pom文件<build>节点下添加

		<resources>
			<resource>
				<directory>src/main/java</directory>
				<includes>
					<include>**/*.xml</include>
				</includes>
			</resource>
		</resources>

说明: 如果不添加此节点mybatis的mapper.xml文件都会被漏掉, 会出现org.apache.ibatis.binding.BindingException Invalid bound statement (not found)异常

1. mapper java

package com.wangzaiplus.test.mapper;

import com.wangzaiplus.test.pojo.User;

import java.util.List;

public interface UserMapper {

    List<User> selectAll();

    User selectOne(Integer id);

    void insert(User user);

    void update(User user);

    void delete(Integer id);

}

说明: 不需要@Select @Insert等注解了

1. 新建UserMapper.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.wangzaiplus.test.mapper.UserMapper" >
    <resultMap id="BaseResultMap" type="com.wangzaiplus.test.pojo.User" >
        <id column="id" property="id" jdbcType="INTEGER" />
        <result column="username" property="username" jdbcType="VARCHAR" />
        <result column="password" property="password" jdbcType="VARCHAR" />
    </resultMap>

    <sql id="Base_Column_List" >
        id, username, password
    </sql>

    <select id="selectAll" resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List" />
        FROM user
    </select>

    <select id="selectOne" parameterType="int" resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List" />
        FROM user
        WHERE id = #{id}
    </select>

    <insert id="insert" parameterType="com.wangzaiplus.test.pojo.User">
        INSERT INTO user(username, password) VALUES (#{username}, #{password})
    </insert>

    <update id="update" parameterType="com.wangzaiplus.test.pojo.User">
        UPDATE user SET
        <if test="username != null">
            username = #{username},
        </if>
        <if test="password != null">
            password = #{password}
        </if>
        WHERE id = #{id}
    </update>

    <delete id="delete" parameterType="int">
        DELETE FROM user WHERE id =#{id}
    </delete>
</mapper>

说明: 相当于将上个版本@Select @Insert注解用xml配置文件形式代替而已