mybatis-plus使用问题的示例分析

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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 byPage = contentService.findByPage(new Page(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 */@Servicepublic class TContentServiceImpl extends ServiceImpl implements TContentService {    @Resource    private TContentMapper tContentMapper;    @Override    public IPage findByPage(Page 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 {    IPage findByPage(Page page, @Param("contentVo") TContentVo contentVo);}

5.mapper.xml，注意入参contentVo

            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`                    1=1             and cid = #{contentVo.cid}             and t.title like concat('%', #{contentVo.title}, '%')             and a.author like concat('%', #{contentVo.author}, '%')             and t.time =${contentVo.time}             and t.content like concat('%', #{contentVo.content}, '%')             and p.topic like concat('%', #{contentVo.topic}, '%')             and f.currentState = -1             and h.currentState = -1                order by time desc    

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的添加xml资源

                                    org.springframework.boot                spring-boot-maven-plugin                                                                    src/main/java                                    **/*.xml                                        

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