springboot整合mybatis（配置文件）

作者：马育民 • • 阅读：10273

准备

springboot 快速入门-创建工程

介绍

springboot整合mybatis，配置方式：

  • 注解+配置文件，sql写在xml中。适合传统大项目
  • 全注解，sql写在注解中。适合简单快速开发

在测试时，需要实现controller、service、mybatis相关类、相关配置文件，以及使用druid数据库连接池，比较复杂，稍有不慎，就会报错

本文使用 注解+配置文件，sql写在xml中

准备mysql表

CREATE TABLE `book` (
    `id` VARCHAR(32) NOT NULL COMMENT '主键' COLLATE 'utf8mb4_unicode_ci',
    `title` VARCHAR(64) NULL DEFAULT NULL COMMENT '书名' COLLATE 'utf8mb4_unicode_ci',
    `author` VARCHAR(64) NULL DEFAULT NULL COMMENT '作者' COLLATE 'utf8mb4_unicode_ci',
    PRIMARY KEY (`id`)
)
COLLATE='utf8mb4_unicode_ci'
ENGINE=InnoDB
;

druid数据库连接池

略

springboot使用druid连mysql5.7（mysql5驱动）

springboot使用druid连mysql5.7（mysql8驱动）

mybatis依赖

找到mybatis依赖

在 https://mvnrepository.com/ 搜索 mybatis，找到MyBatis Spring Boot Starter

添加依赖

将上图中的红框处粘贴到pom.xml文件中

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.0.1</version>
</dependency>

已经包含 spring-boot-starter-jdbc

注意：必须是 2.0.1 以上，否则没有下面用到的 @MapperScan 注解

实体类

package top.malaoshi.entity

public class Book {
    private String id;
    private String title;
    private String author;

    public String getId() {
        return id;
    }

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

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
}

mapper接口

package top.malaoshi.mapper;

import org.apache.ibatis.annotations.Mapper;
import org.example.entity.Book;

@Mapper
public interface BookMapper {

    public int save(Book book);

    public int deleteById(String id);

    public int updateById(Book book);

    public Book getById(String id);
}

让 mapper 接口生效

springboot+mybatis，有2种方式让 mapper 接口生效：

  1. mapper接口由 @Mapper 注解修饰

  2. mapper接口由 @Repository 注解修饰
    主启动类由 @MapperScan("top.malaoshi.mapper") 修饰，扫描 top.malaoshi.mapper 包下的类，使其生效

mapper.xml文件

保存位置

BookMapper.xml 内容

<?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" >

<!-- namespace是接口全路径 -->
<mapper namespace="top.malaoshi.mapper.BookMapper">

    <insert id="save" parameterType="org.example.entity.Book">
        insert into book (id,title,author) values (#{id},#{title},#{author})
    </insert>

    <delete id="deleteById">
        delete from book where id=#{id}
    </delete>

    <update id="updateById" parameterType="org.example.entity.Book">
        update book set title=#{title},author=#{author} where id=#{id}
    </update>

    <select id="getById" resultType="org.example.entity.Book">
        select id,title,author from book where id=#{id}
    </select>
</mapper>

注意：

  • <mapper namespace="top.malaoshi.mapper.BookMapper">必须是BookMapper全路径

mybatis总配置文件

保存位置

在 resources/mybatis 目录下，如下图：

mybatis-config.xml 内容

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
</configuration>

注意： <package name="top.malaoshi.entity"/>必须是上面 实体类的包路径

修改springboot配置文件

整合mybatis

application.yml

增加下面部分

# 整合mybatis
mybatis:
  config-location: classpath:mybatis/mybatis-config.xml   #mybatis总配置文件
  mapperLocations: classpath:mybatis/mapper/*.xml   # xxxMapper.xml配置文件

application.properties

增加下面部分

# 整合mybatis
#mybatis总配置文件
mybatis.config-location: classpath:mybatis/mybatis-config.xml
# xxxMapper.xml配置文件
mybatis.mapperLocations: classpath:mybatis/mapper/*.xml

注意

classpath指src/main/resources路径，

  • classpath:mybatis/mybatis-config.xml指src/main/resources/mybatis/mybatis-config.xml

  • classpath:mybatis/mapper/*.xml指src/main/resources/mybatis/mapper/mybatis-config.xml

创建service接口

package top.malaoshi.service;

import org.example.entity.Book;

public interface IBookService {
    public int save(Book book);
    public int deleteById(String id);
    public int updateById(Book book);
    public Book getById(String id);
}

创建service接口实现类

package top.malaoshi.service.impl;

import top.malaoshi.entity.Book;
import top.malaoshi.mapper.BookMapper;
import top.malaoshi.service.IBookService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.UUID;

@Service
public class BookSrvImpl implements IBookService {

    @Resource
    private BookMapper bookMapper;

    @Override
    public int save(Book book) {
        String uuid= UUID.randomUUID().toString().replace("-","");
        book.setId(uuid);
        int i=bookMapper.save(book);
        return i;
    }

    @Override
    public int deleteById(String id) {
        return bookMapper.deleteById(id);
    }

    @Override
    public int updateById(Book book) {
        return bookMapper.updateById(book);
    }

    @Override
    public Book getById(String id) {
        return bookMapper.getById(id);
    }
}

JsonResult

package top.malaoshi.vo;

import com.fasterxml.jackson.annotation.JsonInclude;

@JsonInclude(JsonInclude.Include.NON_NULL)
public class JsonResult <T> {
    private int code;
    private String msg;
    private T data;

    public JsonResult() {
    }

    public JsonResult(int code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

创建Controller

package top.malaoshi.controller;

import org.springframework.web.bind.annotation.*;
import top.malaoshi.entities.Book;
import top.malaoshi.vo.JsonResult;
import top.malaoshi.service.IBookService;

import javax.annotation.Resource;

import javax.annotation.Resource;

@RestController
public class BookCtrl {

    @Resource
    private IBookService bookService;

    //restful风格
    @PostMapping("/book")
    public JsonResult save(String title,String author){
        Book book=new Book();
        book.setTitle(title);
        book.setAuthor(author);
        bookService.save(book);

        return new JsonResult(0,"success");
    }

    @DeleteMapping("/book/{id}")
    public JsonResult deleteById( @PathVariable String id){
        JsonResult jr=new JsonResult(0,"success");
        int num=bookService.deleteById(id);
        if(num==0){
            jr.setCode(100);
            jr.setMsg("没有该条记录，无法删除！");
        }
        return jr;
    }

    @PutMapping("/book")
    public JsonResult updateById(String id,String title,String author){
        JsonResult jr=new JsonResult(0,"success");
        Book book=new Book();
        book.setId(id);
        book.setTitle(title);
        book.setAuthor(author);
        int num=bookService.updateById(book);
        if(num==0){
            jr.setCode(100);
            jr.setMsg("没有该条记录，无法更新");
        }
        return jr;
    }

    @GetMapping("/book/{id}")
    public JsonResult getById(@PathVariable String id){
        JsonResult<Book> jr=new JsonResult(0,"success");
        Book book=bookService.getById(id);
        jr.setData(book);
        return jr;
    }
}

修改主启动类

mapper 接口使用 @Repository 注解修饰时，需要在主启动类增加下面注解：

@MapperScan("org.example.mapper")

扫描 top.malaoshi.mapper 包下的类，使其生效

注意： 如果 mapper 接口使用 @Mapper 注解修饰，则 不需要修改主启动类（加上也不报错）

例子

@SpringBootApplication
@MapperScan("top.malaoshi.mapper")
public class Main {
    public static void main(String[] args) {
        SpringApplication.run(Main.class,args);
    }
}

为什么增加此注解？

见下面链接：
https://www.malaoshi.top/show_1EF6RCe0gjUK.html

mapper
https://www.cnblogs.com/ityouknow/p/6037431.html

dao
https://segmentfault.com/a/1190000017211657

原文出处：/show_1EF5gW27Vba9.html

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