mybatis-plus使用问题小结

一、多表联合分页查询

1.多表联合查询结果集建议使用VO类，当然也可以使用resultMap

package com.cjhx.tzld.entity.vo;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.cjhx.tzld.entity.TContent;
import com.fasterxml.jackson.annotation.JsonFormat;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;
import org.springframework.format.annotation.DateTimeFormat;
import java.util.Date;
@Data
@ApiModel(value="TContentVo", description="内容池多表联合数据对象")
public class TContentVo extends TContent {
    @ApiModelProperty(value = "编号")
    private Integer cid;
    @ApiModelProperty(value = "内容标题")
    private String title;
    @ApiModelProperty(value = "作者Id")
    @TableField("authorId")
    private Integer authorId;
    @ApiModelProperty(value = "时间")
    @JsonFormat(pattern="yyyy-MM-dd HH:mm:ss",timezone = "GMT+8") //返回时间类型
    @DateTimeFormat(pattern="yyyy-MM-dd HH:mm:ss") //接收时间类型
    private Date time;
    @ApiModelProperty(value = "内容")
    private String content;
    @ApiModelProperty(value = "作者姓名")
    private String author;
    @ApiModelProperty(value = "话题")
    private String topic;
    @ApiModelProperty(value = "模块编号")
    private int moduleNum;
    @ApiModelProperty(value = "模块")
    private String module;
    public TContentVo() {
    }
    public TContentVo(Integer cid, String title, Date time, String content, String author, String topic, int moduleNum) {
        this.cid = cid;
        this.title = title;
        this.time = time;
        this.content = content;
        this.author = author;
        this.topic = topic;
        this.moduleNum = moduleNum;
}

2.controller

package com.cjhx.tzld.controller;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.cjhx.tzld.common.Result;
import com.cjhx.tzld.entity.TContent;
import com.cjhx.tzld.entity.TContentRelationFund;
import com.cjhx.tzld.entity.TTopicPk;
import com.cjhx.tzld.entity.vo.TContentVo;
import com.cjhx.tzld.service.TContentService;
import io.swagger.annotations.*;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
import java.util.Date;
import java.util.List;
/**
 * @since 2022-02-28
 */
@RestController
@RequestMapping("/content")
@Api("内容池模块")
public class ContentController {
    @Resource
    private TContentService contentService;
    @ApiImplicitParams({
            @ApiImplicitParam(name = "cid",value = "cid",dataType = "int",defaultValue = "0",required = false),
            @ApiImplicitParam(name = "title",value = "标题",dataType = "String",defaultValue = "",required = false),
            @ApiImplicitParam(name = "author",value = "作者姓名",dataType = "String",defaultValue = "",required = false),
            @ApiImplicitParam(name = "time",value = "发布时间",dataType = "Date",defaultValue = "",required = false),
            @ApiImplicitParam(name = "content",value = "内容",dataType = "String",defaultValue = "",required = false),
            @ApiImplicitParam(name = "topic",value = "话题",dataType = "String",defaultValue = "",required = false),
            @ApiImplicitParam(name = "moduleNum",value = "投放模块 1热点速递 2基会直达",dataType = "int",defaultValue = "",required = false),
            @ApiImplicitParam(name = "pageIndex",value = "页码",dataType = "int",defaultValue = "1",required = false),
            @ApiImplicitParam(name = "pageSize",value = "每页数量",dataType = "int",defaultValue = "10",required = false)
    })
    @ApiResponses({
            @ApiResponse(code = 200,message = "OK",response = TContent.class)
    @ApiOperation(value="分页获取内容接口(Web端)", notes="支持多条件查询",httpMethod = "GET")
    @RequestMapping(value = "/getContentPage",method = RequestMethod.GET)
    public Result getContentPage(@RequestParam(defaultValue = "0",required = false) int cid,
                                 @RequestParam(defaultValue = "",required = false) String title,
                                 @RequestParam(defaultValue = "",required = false) String author,
                                 @RequestParam(required = false) Date time,
                                 @RequestParam(defaultValue = "",required = false) String content,
                                 @RequestParam(defaultValue = "",required = false) String topic,
                                 @RequestParam(defaultValue = "0",required = false) int moduleNum,
                                 @RequestParam(defaultValue = "1",required = false) int pageIndex,
                                 @RequestParam(defaultValue = "10",required = false)  int pageSize) throws Exception{
        try {
            IPage<TContentVo> byPage = contentService.findByPage(new Page<TContentVo>(pageIndex, pageSize),new TContentVo(cid, title, time, content, author,  topic, moduleNum));
            return Result.success(byPage);
        }catch (Exception e){
            return Result.serviceFail(e.getMessage());
        }
    }
}

3.service

package com.cjhx.tzld.service.impl;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.cjhx.tzld.common.PageUtil;
import com.cjhx.tzld.entity.TContent;
import com.cjhx.tzld.entity.vo.TContentVo;
import com.cjhx.tzld.mapper.TContentMapper;
import com.cjhx.tzld.service.TContentService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.Date;
/**
 * @since 2022-02-28
 */
@Service
public class TContentServiceImpl extends ServiceImpl<TContentMapper, TContent> implements TContentService {
    @Resource
    private TContentMapper tContentMapper;
    @Override
    public IPage<TContentVo> findByPage(Page<TContentVo> page, TContentVo contentVo) {
        return tContentMapper.findByPage(page,contentVo);
    }
}

4.mapper

package com.cjhx.tzld.mapper;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.cjhx.tzld.entity.TContent;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.cjhx.tzld.entity.vo.TContentVo;
import org.apache.ibatis.annotations.Param;
/**
 * @since 2022-02-28
 */
public interface TContentMapper extends BaseMapper<TContent> {
    IPage<TContentVo> findByPage(Page<TContentVo> page, @Param("contentVo") TContentVo contentVo);
}

5.mapper.xml，注意入参contentVo

<?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.cjhx.tzld.mapper.TContentMapper">

    <select id="findByPage" resultType="com.cjhx.tzld.entity.vo.TContentVo" parameterType="com.cjhx.tzld.entity.vo.TContentVo">
        SELECT t.`cid`,t.`authorId`,a.`name`,t.`title`,t.`time`,t.`content`,p.`topic`,h.`title` AS `module`
        FROM `t_content` t
        LEFT JOIN `t_author` a ON a.`aid`=t.`authorId`
        LEFT JOIN `t_topic_pk` p ON p.`cid` = t.`cid`
        LEFT JOIN `t_hot_express` h ON h.`cid` = t.`cid`
        UNION ALL
        SELECT t.`cid`,t.`authorId`,a.`name`,t.`title`,t.`time`,t.`content`,p.`topic`,f.`title` AS `module`
        LEFT JOIN `t_fund_point` f ON f.`cid` = t.`cid`
        <where>
            1=1
            <if test="contentVo.cid > 0"> and cid = #{contentVo.cid}</if>
            <if test="contentVo.title != null and contentVo.title != ''"> and t.title like concat('%', #{contentVo.title}, '%')</if>
            <if test="contentVo.author != null and contentVo.author != ''"> and a.author like concat('%', #{contentVo.author}, '%')</if>
            <if test="contentVo.time != null"> and t.time =${contentVo.time}</if>
            <if test="contentVo.content != null and contentVo.content != ''"> and t.content like concat('%', #{contentVo.content}, '%')</if>
            <if test="contentVo.topic != null and contentVo.topic != ''"> and p.topic like concat('%', #{contentVo.topic}, '%')</if>
            <if test="contentVo.moduleNum == 1"> and f.currentState = -1</if>
            <if test="contentVo.moduleNum == 2"> and h.currentState = -1</if>
        </where>
        order by time desc
    </select>
</mapper>

二、找不到mapper

首先排除@MapperScan("com.cjhx.tzld.mapper")已添加

1.首先配置文件扫描，mapper-locations:classpath:/com/cjhx/tzld/mapper/xml/*.xml

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:/com/cjhx/tzld/mapper/xml/*.xml

2.在pom.xml的<build>添加xml资源

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
        <resources>
            <!--引入mapper对应的xml文件-->
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>

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