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服务器之家 - 编程语言 - Java教程 - Mybatis-Plus BaseMapper的用法详解

Mybatis-Plus BaseMapper的用法详解

2020-08-27 12:52金色的鱼儿 Java教程

这篇文章主要介绍了Mybatis-Plus BaseMapper的用法详解，文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值，需要的朋友们下面随着小编来一起学习学习吧

1、如何使用BaseMapper进行数据库的操作。

2、使用BaseMapper进行插入实体时如何让UUID的主键自动生成。

Student实体类，其中id属性主键为UUID

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package com.huixiaoer.ant.api.model.bean;
 
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
 
public class Student {
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.id
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  @TableId(type= IdType.UUID)
  private String id;
 
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.user_name
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  private String userName;
 
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.age
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  private Integer age;
 
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.phone
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  private String phone;
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public Student(String id, String userName, Integer age, String phone) {
    this.id = id;
    this.userName = userName;
    this.age = age;
    this.phone = phone;
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public Student() {
    super();
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method returns the value of the database column student.id
   *
   * @return the value of student.id
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public String getId() {
    return id;
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method sets the value of the database column student.id
   *
   * @param id the value for student.id
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public void setId(String id) {
    this.id = id == null ? null : id.trim();
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method returns the value of the database column student.user_name
   *
   * @return the value of student.user_name
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public String getUserName() {
    return userName;
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method sets the value of the database column student.user_name
   *
   * @param userName the value for student.user_name
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public void setUserName(String userName) {
    this.userName = userName == null ? null : userName.trim();
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method returns the value of the database column student.age
   *
   * @return the value of student.age
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public Integer getAge() {
    return age;
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method sets the value of the database column student.age
   *
   * @param age the value for student.age
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public void setAge(Integer age) {
    this.age = age;
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method returns the value of the database column student.phone
   *
   * @return the value of student.phone
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public String getPhone() {
    return phone;
  }
 
  /**
   * This method was generated by MyBatis Generator.
   * This method sets the value of the database column student.phone
   *
   * @param phone the value for student.phone
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  public void setPhone(String phone) {
    this.phone = phone == null ? null : phone.trim();
  }
}

StudnetVI实体类，用户从页面接收参数

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package com.huixiaoer.ant.api.model.vi;
 
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
 
@ApiModel(value = "student对象",description = "学生对象student")
public class StudentVI {
 
 
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.user_name
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  @ApiModelProperty(value="学生姓名",name="userName",required=true)
  private String userName;
 
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.age
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  @ApiModelProperty(value="年龄",name="age",required=true)
  private Integer age;
 
  /**
   *
   * This field was generated by MyBatis Generator.
   * This field corresponds to the database column student.phone
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  @ApiModelProperty(value="手机号",name="phone",required=true)
  private String phone;
 
 
  public String getUserName() {
    return userName;
  }
 
  public void setUserName(String userName) {
    this.userName = userName;
  }
 
  public Integer getAge() {
    return age;
  }
 
  public void setAge(Integer age) {
    this.age = age;
  }
 
  public String getPhone() {
    return phone;
  }
 
  public void setPhone(String phone) {
    this.phone = phone;
  }
 
}

StudentPlusMapper接口类，实现BaseMapper用来实现Mybatis-Plus的增强功能。

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package com.huixiaoer.ant.api.repository.mysql.mapper;
 
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.huixiaoer.ant.api.model.bean.Student;
 
public interface StudentPlusMapper extends BaseMapper<Student> {
  //不需要实现，这时候就可以调用baseMapper的增删改查了
}

StudentService业务接口类

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package com.huixiaoer.ant.api.service;
 
import com.huixiaoer.ant.api.model.bean.Student;
import com.huixiaoer.ant.api.model.bean.StudentExample;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.SelectKey;
 
import java.util.List;
 
public interface StudentService {
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  long countByExample(StudentExample example);
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  int deleteByExample(StudentExample example);
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  @Insert({
    "insert into student (id, user_name, ",
    "age, phone)",
    "values (#{id,jdbcType=VARCHAR}, #{userName,jdbcType=VARCHAR}, ",
    "#{age,jdbcType=INTEGER}, #{phone,jdbcType=VARCHAR})"
  })
  @SelectKey(statement="select uuid_short()", keyProperty="id", before=true, resultType=String.class)
  int insert(Student record);
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  int insertSelective(Student record);
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  List<Student> selectByExample(StudentExample example);
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  int updateByExampleSelective(@Param("record") Student record, @Param("example") StudentExample example);
 
  /**
   * This method was generated by MyBatis Generator.
   * This method corresponds to the database table student
   *
   * @mbg.generated Thu Oct 31 14:09:39 CST 2019
   */
  int updateByExample(@Param("record") Student record, @Param("example") StudentExample example);
}

StudentServiceImpl业务接口实现类，这里将mybatis-plus的mapper接口注入其中。

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package com.huixiaoer.ant.api.service.impl;
 
import com.huixiaoer.ant.api.model.bean.Student;
import com.huixiaoer.ant.api.model.bean.StudentExample;
import com.huixiaoer.ant.api.repository.mysql.mapper.StudentMapper;
import com.huixiaoer.ant.api.repository.mysql.mapper.StudentPlusMapper;
import com.huixiaoer.ant.api.service.StudentService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
 
@Service
@Slf4j
public class StudentServiceImpl implements StudentService {
 
  @Autowired
  private StudentMapper studentMapper;
 
  @Autowired
  private StudentPlusMapper studentPlusMapper;
 
  @Override
  public long countByExample(StudentExample example) {
    return 0;
  }
 
  @Override
  public int deleteByExample(StudentExample example) {
    return 0;
  }
 
  @Override
  public int insert(Student record) {
    return studentPlusMapper.insert(record);
  }
 
  @Override
  public int insertSelective(Student record) {
    return studentMapper.insertSelective(record);
  }
 
  @Override
  public List<Student> selectByExample(StudentExample example) {
    return null;
  }
 
  @Override
  public int updateByExampleSelective(Student record, StudentExample example) {
    return 0;
  }
 
  @Override
  public int updateByExample(Student record, StudentExample example) {
    return 0;
  }
}

SchoolController类，实现前端和后台的交互。自动注入学生业务实现类。

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package com.huixiaoer.ant.api.controller;
 
import com.huixiaoer.ant.api.common.constant.ResultCode;
import com.huixiaoer.ant.api.model.bean.Student;
import com.huixiaoer.ant.api.model.vi.StudentVI;
import com.huixiaoer.ant.api.service.impl.StudentServiceImpl;
import com.huixiaoer.ant.api.util.*;
import io.swagger.annotations.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.UUID;
 
/**
 * @author create by yiqiang.wu
 * @create 2019/06/12
 * @email yiqiang.wu@huixiaoer.com
 * @description 登录
 */
@Slf4j
@RestController
@Api(tags = "学校 相关接口")
public class SchoolController {
 
  @Autowired
  private StudentServiceImpl studentService;
 
  @Autowired
  private HttpServletRequest request;
 
  @ApiOperation(value = "增加学生信息")
  @PostMapping(value = "/insert/student")
  public CommonResult insertStudent(@RequestBody @ApiParam(name="学生对象",value="传入json格式",required=true) StudentVI studentVI) {
    try {
      Student student = new Student();
//      student.setId(UUID.randomUUID().toString());
      student.setUserName(studentVI.getUserName());
      student.setAge(studentVI.getAge());
      student.setPhone(studentVI.getPhone());
      studentService.insert(student);
    } catch (Exception e) {
      System.out.println(e);
      return CommonUtil.buildResponse(ResultCode.SYSTEM_ERROR, ResultCode.SYSTEM_ERROR_MSG);
    }
    return CommonUtil.buildResponse(ResultCode.SUCCESS, ResultCode.SUCCESS_MSG);
  }
 
}

补充一下Mybatis的xml文件

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<?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.huixiaoer.ant.api.repository.mysql.mapper.StudentMapper">
 <resultMap id="BaseResultMap" type="com.huixiaoer.ant.api.model.bean.Student">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  <constructor>
   <arg column="id" javaType="java.lang.String" jdbcType="VARCHAR" />
   <arg column="user_name" javaType="java.lang.String" jdbcType="VARCHAR" />
   <arg column="age" javaType="java.lang.Integer" jdbcType="INTEGER" />
   <arg column="phone" javaType="java.lang.String" jdbcType="VARCHAR" />
  </constructor>
 </resultMap>
 <sql id="Example_Where_Clause">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  <where>
   <foreach collection="oredCriteria" item="criteria" separator="or">
    <if test="criteria.valid">
     <trim prefix="(" prefixOverrides="and" suffix=")">
      <foreach collection="criteria.criteria" item="criterion">
       <choose>
        <when test="criterion.noValue">
         and ${criterion.condition}
        </when>
        <when test="criterion.singleValue">
         and ${criterion.condition} #{criterion.value}
        </when>
        <when test="criterion.betweenValue">
         and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
        </when>
        <when test="criterion.listValue">
         and ${criterion.condition}
         <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
          #{listItem}
         </foreach>
        </when>
       </choose>
      </foreach>
     </trim>
    </if>
   </foreach>
  </where>
 </sql>
 <sql id="Update_By_Example_Where_Clause">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  <where>
   <foreach collection="example.oredCriteria" item="criteria" separator="or">
    <if test="criteria.valid">
     <trim prefix="(" prefixOverrides="and" suffix=")">
      <foreach collection="criteria.criteria" item="criterion">
       <choose>
        <when test="criterion.noValue">
         and ${criterion.condition}
        </when>
        <when test="criterion.singleValue">
         and ${criterion.condition} #{criterion.value}
        </when>
        <when test="criterion.betweenValue">
         and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
        </when>
        <when test="criterion.listValue">
         and ${criterion.condition}
         <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
          #{listItem}
         </foreach>
        </when>
       </choose>
      </foreach>
     </trim>
    </if>
   </foreach>
  </where>
 </sql>
 <sql id="Base_Column_List">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  id, user_name, age, phone
 </sql>
 <select id="selectByExample" parameterType="com.huixiaoer.ant.api.model.bean.StudentExample" resultMap="BaseResultMap">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  select
  <if test="distinct">
   distinct
  </if>
  <include refid="Base_Column_List" />
  from student
  <if test="_parameter != null">
   <include refid="Example_Where_Clause" />
  </if>
  <if test="orderByClause != null">
   order by ${orderByClause}
  </if>
 </select>
 <delete id="deleteByExample" parameterType="com.huixiaoer.ant.api.model.bean.StudentExample">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  delete from student
  <if test="_parameter != null">
   <include refid="Example_Where_Clause" />
  </if>
 </delete>
 <insert id="insertSelective" parameterType="com.huixiaoer.ant.api.model.bean.Student">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  <selectKey keyProperty="id" order="BEFORE" resultType="java.lang.String">
   select uuid_short()
  </selectKey>
  insert into student
  <trim prefix="(" suffix=")" suffixOverrides=",">
   id,
   <if test="userName != null">
    user_name,
   </if>
   <if test="age != null">
    age,
   </if>
   <if test="phone != null">
    phone,
   </if>
  </trim>
  <trim prefix="values (" suffix=")" suffixOverrides=",">
   #{id,jdbcType=VARCHAR},
   <if test="userName != null">
    #{userName,jdbcType=VARCHAR},
   </if>
   <if test="age != null">
    #{age,jdbcType=INTEGER},
   </if>
   <if test="phone != null">
    #{phone,jdbcType=VARCHAR},
   </if>
  </trim>
 </insert>
 <select id="countByExample" parameterType="com.huixiaoer.ant.api.model.bean.StudentExample" resultType="java.lang.Long">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  select count(*) from student
  <if test="_parameter != null">
   <include refid="Example_Where_Clause" />
  </if>
 </select>
 <update id="updateByExampleSelective" parameterType="map">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  update student
  <set>
   <if test="record.id != null">
    id = #{record.id,jdbcType=VARCHAR},
   </if>
   <if test="record.userName != null">
    user_name = #{record.userName,jdbcType=VARCHAR},
   </if>
   <if test="record.age != null">
    age = #{record.age,jdbcType=INTEGER},
   </if>
   <if test="record.phone != null">
    phone = #{record.phone,jdbcType=VARCHAR},
   </if>
  </set>
  <if test="_parameter != null">
   <include refid="Update_By_Example_Where_Clause" />
  </if>
 </update>
 <update id="updateByExample" parameterType="map">
  <!--
   WARNING - @mbg.generated
   This element is automatically generated by MyBatis Generator, do not modify.
   This element was generated on Thu Oct 31 14:09:39 CST 2019.
  -->
  update student
  set id = #{record.id,jdbcType=VARCHAR},
   user_name = #{record.userName,jdbcType=VARCHAR},
   age = #{record.age,jdbcType=INTEGER},
   phone = #{record.phone,jdbcType=VARCHAR}
  <if test="_parameter != null">
   <include refid="Update_By_Example_Where_Clause" />
  </if>
 </update>
</mapper>

各种UUID生成策略，生成的UUID值进行比较。

Mybatis-Plus BaseMapper的用法详解

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原文链接：https://www.cnblogs.com/it-deepinmind/p/11772955.html

  • MyBatis-Plus
  • BaseMapper

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