mybatis-plus使用问题汇总

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`
        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_fund_point` f ON f.`cid` = t.`cid`
        <where>
            <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>

 

三、配置汇总maven

<dependencies>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.1.tmp</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.3.1.tmp</version>
        </dependency>
        <!-- 添加 模板引擎 依赖 -->
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!-- swagger -->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
        <!-- 引入swagger-bootstrap-ui包 /doc.html-->
        <dependency>
            <groupId>com.github.xiaoymin</groupId>
            <artifactId>swagger-bootstrap-ui</artifactId>
            <version>1.9.1</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
    </dependencies>

四、自动生成代码

generatorConfig.xml放在当前项目下与src一个层级

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>
    <context id="testTables" targetRuntime="MyBatis3">
        <commentGenerator>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true" />
        </commentGenerator>
        <!--数据库连接的信息：驱动类、连接地址、用户名、密码 #######修改1：修改成自己的数据库名，用户及密码-->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/eladmin?useSSL=true" userId="root"
                        password="123456">
        </jdbcConnection>
        <!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 和
            NUMERIC 类型解析为java.math.BigDecimal -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- targetProject:生成PO类的位置 #######修改2：修改生成实体类文件的包名-->
        <javaModelGenerator targetPackage="me.zhengjie.pojo"
                            targetProject=".\src\main\java">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false" />
            <!-- 从数据库返回的值被清理前后的空格 -->
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
        <!-- targetProject:mapper映射文件生成的位置 #######修改3：mapper.xml文件的包名-->
        <sqlMapGenerator targetPackage="dbconfig"
                         targetProject=".\src\main\resources">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false" />
        </sqlMapGenerator>
        <!-- targetPackage：mapper接口生成的位置 #######4:mapper.xml文件的路径-->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="me.zhengjie.mapper"
                             targetProject=".\src\main\java">
            <!-- enableSubPackages:是否让schema作为包的后缀 -->
            <property name="enableSubPackages" value="false" />
        </javaClientGenerator>
        <!-- 指定数据库表 -->
        <table schema="" tableName="bd_additional"></table>
        <table schema="" tableName="bd_claimdocuments"></table>
        <table schema="" tableName="bd_customer"></table>
        <table schema="" tableName="bd_documents"></table>
        <table schema="" tableName="bd_insuredinfo"></table>
        <table schema="" tableName="bd_policyholderinfo"></table>
        <table schema="" tableName="bd_settleclaim"></table>
        <table schema="" tableName="bd_warranty"></table>
    </context>
</generatorConfiguration>

GeneratorCode 执行main方法生成代码

package me.zhengjie;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.config.DataSourceConfig;
import com.baomidou.mybatisplus.generator.config.GlobalConfig;
import com.baomidou.mybatisplus.generator.config.PackageConfig;
import com.baomidou.mybatisplus.generator.config.StrategyConfig;
import com.baomidou.mybatisplus.generator.config.po.TableFill;
import com.baomidou.mybatisplus.generator.config.rules.DateType;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;

import java.util.ArrayList;

public class GeneratorCode {

    public static void main(String[] args) {
        // 需要构建一个 代码自动生成器 对象
        AutoGenerator mpg = new AutoGenerator();
        // 配置策略
        // 1、全局配置
        GlobalConfig gc = new GlobalConfig();
        String projectPath = System.getProperty("user.dir");
        gc.setOutputDir(projectPath+"/src/main/java");
        gc.setAuthor("lanhaifeng");
        gc.setOpen(false);
        gc.setFileOverride(false); // 是否覆盖
        gc.setServiceName("%sService"); // 去Service的I前缀
        gc.setIdType(IdType.ID_WORKER);
        gc.setDateType(DateType.ONLY_DATE);
        gc.setSwagger2(true);
        mpg.setGlobalConfig(gc);
        //2、设置数据源
        DataSourceConfig dsc = new DataSourceConfig();
        dsc.setUrl("jdbc:mysql://localhost:3306/eladmin?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8");
        dsc.setDriverName("com.mysql.cj.jdbc.Driver");
        dsc.setUsername("root");
        dsc.setPassword("123456");
        dsc.setDbType(DbType.MYSQL);
        mpg.setDataSource(dsc);
        //3、包的配置
        PackageConfig pc = new PackageConfig();
        pc.setModuleName("zhengjie");
        pc.setParent("me");
        pc.setEntity("entity");
        pc.setMapper("mapper");
        pc.setService("service");
        pc.setController("controller");
        mpg.setPackageInfo(pc);
        //4、策略配置
        StrategyConfig strategy = new StrategyConfig();
        strategy.setInclude("bd_additional","bd_claimdocuments","bd_customer","bd_documents",
                "bd_insuredinfo","bd_policyholderinfo","bd_settleclaim","bd_warranty"
                ); // 设置要映射的表名
        strategy.setNaming(NamingStrategy.underline_to_camel);
        strategy.setColumnNaming(NamingStrategy.underline_to_camel);
        strategy.setEntityLombokModel(true); // 自动lombok；
        strategy.setLogicDeleteFieldName("deleted");
        strategy.setTablePrefix("bd_");//去掉表名前缀
        // 自动填充配置
        TableFill gmtCreate = new TableFill("gmt_create", FieldFill.INSERT);
        TableFill gmtModified = new TableFill("gmt_modified", FieldFill.INSERT_UPDATE);
        ArrayList<TableFill> tableFills = new ArrayList<>();
        tableFills.add(gmtCreate);
        tableFills.add(gmtModified);
        strategy.setTableFillList(tableFills);
        // 乐观锁
        strategy.setVersionFieldName("version");
        strategy.setRestControllerStyle(true);
        strategy.setControllerMappingHyphenStyle(true); //localhost:8080/hello_id_2
        mpg.setStrategy(strategy);
        mpg.execute(); //执行
    }

}

 五、查询部分字段

大多时候不需要查询整个表的所有字段，只想查询自己想要的

QueryWrapper<User> queryWrapper = new QueryWrapper<>();
 queryWrapper.select("name", "phone").eq("age",25);
 List<User> users = userMapper.selectList(queryWrapper);

屏蔽某些字段

ueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select(User.class, info -> !info.getColumn().equals("age")
                && !info.getColumn().equals("address")).eq("name","jack");
List<User> users = userMapper.selectList(queryWrapper);

 六、分页不显示总条数

package me.zhengjie.config;

import org.mybatis.spring.annotation.MapperScan;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
public class MybatisPlusConfig {

    /**
     * 分页插件
     * @return
     */
    @Bean
    public PaginationInterceptor paginationInterceptor() {
        return new PaginationInterceptor();
    }

}