关于mybatis-plus一些使用总结

        项目中用到mybatis-plus这个dao框架，一些自带的方法很好用，一直会使用但是不会搭建及一些其中的原理不是很了解。先模仿下，供以后参考吧。（基于springboot）

一、pom文件引入依赖

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.7.1</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>

二、application启动类文件

这里主要是@MapperScan注解

package com.lsl.mylsl;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@EnableTransactionManagement
@SpringBootApplication
@MapperScan({"com.lsl.mylsl.mapper","com.lsl.*.mylsl.mapper"})
public class MylslApplication {

    public static void main(String[] args) {
//        ConfigurableApplicationContext context = SpringApplication.run(MylslApplication.class, args);
//        System.err.println("local.ip=" + context.getEnvironment().getProperty("local.ip"));
//        context.getBean(MyConfig.class).show();
//        System.out.println(context.getBean("propertiesConfig"));
//        System.out.println(context.getBean(MyEnvironmentPostProcessor.class));
//        System.out.println("springboot.name=" + context.getEnvironment().getProperty("springboot.name"));


//        context.close();
        SpringApplication.run(MylslApplication.class, args);
    }

}

三、相关controller，service，BO,mapper及mapper.xml

 1、controller

@CrossOrigin这个是解决跨域的注解

package com.lsl.mylsl.controller;


import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
import com.lsl.mylsl.BO.CatBO;
import com.lsl.mylsl.service.ICatService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.UUID;

@CrossOrigin(allowCredentials = "true")
@RestController
@RequestMapping("/api/lsl")
public class CatController {

    @Autowired
    ICatService  catService;

    @PostMapping(value = "qryCat",produces = "application/json;charset=UTF-8")
    public String qryCatByAge(@RequestBody Map params){
        String catId = params.get("catId").toString();
        String catAge = params.get("catAge").toString();
        String catName = params.get("catName").toString();

        //mybatis-plus自带方法--查询list
        List<CatBO> catList = catService.list(new QueryWrapper<CatBO>()
                .eq("cat_id", catId).isNotNull("cat_status"));
        //mybatis-plus自带方法--查一条记录
        CatBO catBO1 = catService.getById(catId);
        //mybatis-plus自带方法--查一条记录
        CatBO catBO2 = catService.getOne(new QueryWrapper<CatBO>().eq("cat_id", catId));

        //mybatis-plus自带方法--插入一条记录
        CatBO bo = new CatBO();
        String catId1 = UUID.randomUUID().toString();
        bo.setCatId(catId1);
        bo.setCatAge("6");
        bo.setCatName("haha");
        catService.save(bo);

        //mybatis-plus自带方法--批量插入记录
        List<CatBO> listBo = new ArrayList<>();
        listBo.add(bo);
        catService.saveBatch(listBo);


        //mybatis-plus自带方法--更新
        UpdateWrapper updateWrapper = new UpdateWrapper();
        updateWrapper.eq("cat_id",catId);
        updateWrapper.set("cat_age",catAge);
        updateWrapper.set("cat_name",catName);
        catService.update(updateWrapper);

        //自己写的sql
        List<Map> mapList = catService.qryCatByAge(params);

        return "";

    }
}

2、service

package com.lsl.mylsl.service;

import com.baomidou.mybatisplus.extension.service.IService;
import com.lsl.mylsl.BO.CatBO;

import java.util.List;
import java.util.Map;

public interface ICatService extends IService<CatBO> {

    List<Map> qryCatByAge(Map params);
}

package com.lsl.mylsl.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.lsl.mylsl.BO.CatBO;
import com.lsl.mylsl.mapper.CatMapper;
import com.lsl.mylsl.service.ICatService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

@Service
public class CatServiceImpl extends ServiceImpl<CatMapper, CatBO> implements ICatService {

    @Autowired
    CatMapper catMapper;

    @Override
    public List<Map> qryCatByAge(Map params) {
        //返回字段为数据库字段一直，如果数据库字段是大写，则也是大写
        return catMapper.qryCatByAge(params);
    }
}

3、mapper

package com.lsl.mylsl.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.lsl.mylsl.BO.CatBO;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Map;

@Repository
public interface CatMapper extends BaseMapper<CatBO> {

    List<Map> qryCatByAge(Map params);

    int qryCatCount(Map params);

    List<Map> qryCatByid(Map params);

    void updCatAge(Map params);
}

4、mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTO Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.lsl.mylsl.mapper.CatMapper">


    <!--分页查询 -->
    <select id="qryCatByAge" resultType="java.util.Map" parameterType="java.util.Map">
        select
        *
        from
        (
        select
        QS.*,
        ROWNUM RN
        from
        (
        select * from tab_cat<where>
            <if test="catAge !=null and catAge !='' ">cat_age>#{catAge}
            </if>

            <if test="sortBy !=null and sortBy !='' ">
                order by NLSSORT($(sortBy),'NLS_SORT=SCHINESE_PINYIN_M')
            </if>

            <if test="order !=null and order !='' ">
                ${order}
            </if>


        </where>
        ) QS
        )
        where RN between (${page}-1) * ${limit} +1 and ${page}*${limit}
    </select>

    <!-- 查询记录总数-->
    <select id="qryCatCount" resultType="int" parameterType="map">
        select count(1) from tab_cat where cat_age>#{catAge}
    </select>

    <!-- 不分页查询记录-->
    <select id="qryCatByid" resultType="int" parameterType="map">
        <![CDATA[
            select * from tab_cat where cat_id>#{catId}
        ]]>
    </select>

    <!-- 更新记录-->
    <update id="updCatAge" parameterType="map">
        <![CDATA[
            update tab_cat set cat_age=#{catAge} where cat_id>#{catId}
        ]]>
    </update>

</mapper>

5、BO

package com.lsl.mylsl.BO;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

import java.io.Serializable;

@TableName("tab_cat")
public class CatBO implements Serializable {
    private static final long serialVersionUID = 1765207774189824729L;

    @TableId(type = IdType.UUID)
    private String catId;
    @TableField("CAT_NAME")
    private String catName;
    @TableField("CAT_AGE")
    private String catAge;

    //该字段在数据库中不存在，业务需要，不会映射到表
    @TableField(exist = false)
    private String catNum;

    public String getCatId() {
        return catId;
    }

    public void setCatId(String catId) {
        this.catId = catId;
    }

    public String getCatName() {
        return catName;
    }

    public void setCatName(String catName) {
        this.catName = catName;
    }

    public String getCatAge() {
        return catAge;
    }

    public void setCatAge(String catAge) {
        this.catAge = catAge;
    }

    public String getCatNum() {
        return catNum;
    }

    public void setCatNum(String catNum) {
        this.catNum = catNum;
    }
}

四、项目结构