11.1、正向与逆向工程概述

  • 正向工程：先创建Java实体类，由框架负责根据实体类生成数据库表；例如Hibernate是支持正向工程的。

  • 逆向工程：先创建数据库表，由框架负责根据数据库表，反向生成Java实体类、mapper接口和映射文件。

11.2、环境搭建

11.2.1、创建新module

创建名为mybatis_mbg的新module，过程参考5.1节

11.2.2、添加打包方式和依赖及插件

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0"
  3.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  5.     <modelVersion>4.0.0</modelVersion>
  7.     <groupId>org.rain</groupId>
  8.     <artifactId>mybatis_mbg</artifactId>
  9.     <version>1.0-SNAPSHOT</version>
  10.     <!--打包方式-->
  11.     <packaging>jar</packaging>
  13.     <!--依赖-->
  14.     <dependencies>
  15.         <!-- Mybatis核心 -->
  16.         <dependency>
  17.             <groupId>org.mybatis</groupId>
  18.             <artifactId>mybatis</artifactId>
  19.             <version>3.5.7</version>
  20.         </dependency>
  21.         <!-- junit测试 -->
  22.         <dependency>
  23.             <groupId>junit</groupId>
  24.             <artifactId>junit</artifactId>
  25.             <version>4.12</version>
  26.             <scope>test</scope>
  27.         </dependency>
  28.         <!-- MySQL驱动 -->
  29.         <dependency>
  30.             <groupId>mysql</groupId>
  31.             <artifactId>mysql-connector-java</artifactId>
  32.             <version>5.1.49</version>
  33.         </dependency>
  34.         <!-- log4j日志 -->
  35.         <dependency>
  36.             <groupId>log4j</groupId>
  37.             <artifactId>log4j</artifactId>
  38.             <version>1.2.17</version>
  39.         </dependency>
  40.     </dependencies>
  42.     <build>
  43.         <!-- 构建过程中用到的插件 -->
  44.         <plugins>
  45.             <!-- 具体插件，逆向工程的操作是以构建过程中插件形式出现的 -->
  46.             <plugin>
  47.                 <groupId>org.mybatis.generator</groupId>
  48.                 <artifactId>mybatis-generator-maven-plugin</artifactId>
  49.                 <version>1.3.0</version>
  50.                 <!-- 插件的依赖 -->
  51.                 <dependencies>
  52.                     <!-- 逆向工程的核心依赖 -->
  53.                     <dependency>
  54.                         <groupId>org.mybatis.generator</groupId>
  55.                         <artifactId>mybatis-generator-core</artifactId>
  56.                         <version>1.3.2</version>
  57.                     </dependency>
  58.                     <!-- MySQL驱动 -->
  59.                     <dependency>
  60.                         <groupId>mysql</groupId>
  61.                         <artifactId>mysql-connector-java</artifactId>
  62.                         <version>5.1.49</version>
  63.                     </dependency>
  64.                 </dependencies>
  65.             </plugin>
  66.         </plugins>
  67.     </build>
  69. </project>

11.3、创建逆向工程的配置文件

注意：文件名必须是generatorConfig.xml

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <!DOCTYPE generatorConfiguration
  3.         PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
  5. <generatorConfiguration>
  6.     <!--
  7.     targetRuntime属性: 设置执行生成逆向工程的版本
  8.         MyBatis3Simple: 生成基本的CRUD（简洁版）
  9.         MyBatis3: 生成带条件的CRUD（进阶版）
  10.     -->
  11.     <context id="DB2Tables" targetRuntime="MyBatis3Simple">
  12.         <!-- 数据库的连接信息 -->
  13.         <jdbcConnection driverClass="com.mysql.jdbc.Driver"
  14.                         connectionURL="jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8"
  15.                         userId="root"
  16.                         password="root">
  17.         </jdbcConnection>
  18.         <!-- javaBean的生成策略-->
  19.         <javaModelGenerator targetPackage="org.rain.mybatis.pojo" targetProject=".\src\main\java">
  20.             <property name="enableSubPackages" value="true" />
  21.             <property name="trimStrings" value="true" />
  22.         </javaModelGenerator>
  23.         <!-- SQL映射文件的生成策略 -->
  24.         <sqlMapGenerator targetPackage="org.rain.mybatis.mapper" targetProject=".\src\main\resources">
  25.             <property name="enableSubPackages" value="true" />
  26.         </sqlMapGenerator>
  27.         <!-- Mapper接口的生成策略 -->
  28.         <javaClientGenerator type="XMLMAPPER" targetPackage="org.rain.mybatis.mapper" targetProject=".\src\main\java">
  29.             <property name="enableSubPackages" value="true" />
  30.         </javaClientGenerator>
  31.         <!-- 逆向分析的表 -->
  32.         <!-- tableName设置为*号，可以对应所有表，此时不写domainObjectName -->
  33.         <!-- domainObjectName属性指定生成出来的实体类的类名 -->
  34.         <table tableName="t_emp" domainObjectName="Emp"/>
  35.         <table tableName="t_dept" domainObjectName="Dept"/>
  36.     </context>
  37. </generatorConfiguration>

11.4、执行mybatis-generator插件

  • 找到mybatis-generator插件，并双击执行

11.5、插件执行效果(简洁版)

11.5.1、总体概览

注意：如图所示，实体类、接口和映射文件都自动生成了

11.5.2、实体类生成内容示例

  1. package org.rain.mybatis.pojo;
  3. public class Dept {
  4.     /**
  5.      * This field was generated by MyBatis Generator.
  6.      * This field corresponds to the database column t_dept.dept_id
  7.      *
  8.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  9.      */
  10.     private Integer deptId;
  12.     /**
  13.      * This field was generated by MyBatis Generator.
  14.      * This field corresponds to the database column t_dept.dept_name
  15.      *
  16.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  17.      */
  18.     private String deptName;
  20.     /**
  21.      * This method was generated by MyBatis Generator.
  22.      * This method returns the value of the database column t_dept.dept_id
  23.      *
  24.      * @return the value of t_dept.dept_id
  25.      *
  26.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  27.      */
  28.     public Integer getDeptId() {
  29.         return deptId;
  30.     }
  32.     /**
  33.      * This method was generated by MyBatis Generator.
  34.      * This method sets the value of the database column t_dept.dept_id
  35.      *
  36.      * @param deptId the value for t_dept.dept_id
  37.      *
  38.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  39.      */
  40.     public void setDeptId(Integer deptId) {
  41.         this.deptId = deptId;
  42.     }
  44.     /**
  45.      * This method was generated by MyBatis Generator.
  46.      * This method returns the value of the database column t_dept.dept_name
  47.      *
  48.      * @return the value of t_dept.dept_name
  49.      *
  50.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  51.      */
  52.     public String getDeptName() {
  53.         return deptName;
  54.     }
  56.     /**
  57.      * This method was generated by MyBatis Generator.
  58.      * This method sets the value of the database column t_dept.dept_name
  59.      *
  60.      * @param deptName the value for t_dept.dept_name
  61.      *
  62.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  63.      */
  64.     public void setDeptName(String deptName) {
  65.         this.deptName = deptName == null ? null : deptName.trim();
  66.     }
  67. }

11.5.3、mapper接口生成内容示例

  1. package org.rain.mybatis.mapper;
  3. import java.util.List;
  4. import org.rain.mybatis.pojo.Dept;
  6. public interface DeptMapper {
  7.     /**
  8.      * This method was generated by MyBatis Generator.
  9.      * This method corresponds to the database table t_dept
  10.      *
  11.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  12.      */
  13.     int deleteByPrimaryKey(Integer deptId);
  15.     /**
  16.      * This method was generated by MyBatis Generator.
  17.      * This method corresponds to the database table t_dept
  18.      *
  19.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  20.      */
  21.     int insert(Dept record);
  23.     /**
  24.      * This method was generated by MyBatis Generator.
  25.      * This method corresponds to the database table t_dept
  26.      *
  27.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  28.      */
  29.     Dept selectByPrimaryKey(Integer deptId);
  31.     /**
  32.      * This method was generated by MyBatis Generator.
  33.      * This method corresponds to the database table t_dept
  34.      *
  35.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  36.      */
  37.     List<Dept> selectAll();
  39.     /**
  40.      * This method was generated by MyBatis Generator.
  41.      * This method corresponds to the database table t_dept
  42.      *
  43.      * @mbggenerated Wed Jul 05 11:25:17 CST 2023
  44.      */
  45.     int updateByPrimaryKey(Dept record);
  46. }

11.5.4、映射文件生成内容示例

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
  3. <mapper namespace="org.rain.mybatis.mapper.DeptMapper" >
  4.   <resultMap id="BaseResultMap" type="org.rain.mybatis.pojo.Dept" >
  5.     <!--
  6.       WARNING - @mbggenerated
  7.       This element is automatically generated by MyBatis Generator, do not modify.
  8.       This element was generated on Wed Jul 05 11:25:17 CST 2023.
  9.     -->
  10.     <id column="dept_id" property="deptId" jdbcType="INTEGER" />
  11.     <result column="dept_name" property="deptName" jdbcType="VARCHAR" />
  12.   </resultMap>
  13.   <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
  14.     <!--
  15.       WARNING - @mbggenerated
  16.       This element is automatically generated by MyBatis Generator, do not modify.
  17.       This element was generated on Wed Jul 05 11:25:17 CST 2023.
  18.     -->
  19.     delete from t_dept
  20.     where dept_id = #{deptId,jdbcType=INTEGER}
  21.   </delete>
  22.   <insert id="insert" parameterType="org.rain.mybatis.pojo.Dept" >
  23.     <!--
  24.       WARNING - @mbggenerated
  25.       This element is automatically generated by MyBatis Generator, do not modify.
  26.       This element was generated on Wed Jul 05 11:25:17 CST 2023.
  27.     -->
  28.     insert into t_dept (dept_id, dept_name)
  29.     values (#{deptId,jdbcType=INTEGER}, #{deptName,jdbcType=VARCHAR})
  30.   </insert>
  31.   <update id="updateByPrimaryKey" parameterType="org.rain.mybatis.pojo.Dept" >
  32.     <!--
  33.       WARNING - @mbggenerated
  34.       This element is automatically generated by MyBatis Generator, do not modify.
  35.       This element was generated on Wed Jul 05 11:25:17 CST 2023.
  36.     -->
  37.     update t_dept
  38.     set dept_name = #{deptName,jdbcType=VARCHAR}
  39.     where dept_id = #{deptId,jdbcType=INTEGER}
  40.   </update>
  41.   <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
  42.     <!--
  43.       WARNING - @mbggenerated
  44.       This element is automatically generated by MyBatis Generator, do not modify.
  45.       This element was generated on Wed Jul 05 11:25:17 CST 2023.
  46.     -->
  47.     select dept_id, dept_name
  48.     from t_dept
  49.     where dept_id = #{deptId,jdbcType=INTEGER}
  50.   </select>
  51.   <select id="selectAll" resultMap="BaseResultMap" >
  52.     <!--
  53.       WARNING - @mbggenerated
  54.       This element is automatically generated by MyBatis Generator, do not modify.
  55.       This element was generated on Wed Jul 05 11:25:17 CST 2023.
  56.     -->
  57.     select dept_id, dept_name
  58.     from t_dept
  59.   </select>
  60. </mapper>

11.6、进阶版逆向工程

11.6.1、修改逆向工程配置文件

11.6.2、删除之前简单版生成的内容

++++++++++++++++++++分割线++++++++++++++++++++++

11.6.3、执行mybatis-generator插件

11.6.4、插件执行效果(进阶版)

11.6.4.1、总体概览

注意：进阶版生成的实体类，比简洁版的多了xxxExample

11.6.4.2、实体类生成内容示例

  1. package org.rain.mybatis.pojo;
  3. public class Dept {
  4.     /**
  5.      * This field was generated by MyBatis Generator.
  6.      * This field corresponds to the database column t_dept.dept_id
  7.      *
  8.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  9.      */
  10.     private Integer deptId;
  12.     /**
  13.      * This field was generated by MyBatis Generator.
  14.      * This field corresponds to the database column t_dept.dept_name
  15.      *
  16.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  17.      */
  18.     private String deptName;
  20.     /**
  21.      * This method was generated by MyBatis Generator.
  22.      * This method returns the value of the database column t_dept.dept_id
  23.      *
  24.      * @return the value of t_dept.dept_id
  25.      *
  26.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  27.      */
  28.     public Integer getDeptId() {
  29.         return deptId;
  30.     }
  32.     /**
  33.      * This method was generated by MyBatis Generator.
  34.      * This method sets the value of the database column t_dept.dept_id
  35.      *
  36.      * @param deptId the value for t_dept.dept_id
  37.      *
  38.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  39.      */
  40.     public void setDeptId(Integer deptId) {
  41.         this.deptId = deptId;
  42.     }
  44.     /**
  45.      * This method was generated by MyBatis Generator.
  46.      * This method returns the value of the database column t_dept.dept_name
  47.      *
  48.      * @return the value of t_dept.dept_name
  49.      *
  50.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  51.      */
  52.     public String getDeptName() {
  53.         return deptName;
  54.     }
  56.     /**
  57.      * This method was generated by MyBatis Generator.
  58.      * This method sets the value of the database column t_dept.dept_name
  59.      *
  60.      * @param deptName the value for t_dept.dept_name
  61.      *
  62.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  63.      */
  64.     public void setDeptName(String deptName) {
  65.         this.deptName = deptName == null ? null : deptName.trim();
  66.     }
  67. }

11.6.4.3、实体类Example生成内容示例

  1. package org.rain.mybatis.pojo;
  3. import java.util.ArrayList;
  4. import java.util.List;
  6. public class DeptExample {
  7.     /**
  8.      * This field was generated by MyBatis Generator.
  9.      * This field corresponds to the database table t_dept
  10.      *
  11.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  12.      */
  13.     protected String orderByClause;
  15.     /**
  16.      * This field was generated by MyBatis Generator.
  17.      * This field corresponds to the database table t_dept
  18.      *
  19.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  20.      */
  21.     protected boolean distinct;
  23.     /**
  24.      * This field was generated by MyBatis Generator.
  25.      * This field corresponds to the database table t_dept
  26.      *
  27.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  28.      */
  29.     protected List<Criteria> oredCriteria;
  31.     /**
  32.      * This method was generated by MyBatis Generator.
  33.      * This method corresponds to the database table t_dept
  34.      *
  35.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  36.      */
  37.     public DeptExample() {
  38.         oredCriteria = new ArrayList<Criteria>();
  39.     }
  41.     /**
  42.      * This method was generated by MyBatis Generator.
  43.      * This method corresponds to the database table t_dept
  44.      *
  45.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  46.      */
  47.     public void setOrderByClause(String orderByClause) {
  48.         this.orderByClause = orderByClause;
  49.     }
  51.     /**
  52.      * This method was generated by MyBatis Generator.
  53.      * This method corresponds to the database table t_dept
  54.      *
  55.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  56.      */
  57.     public String getOrderByClause() {
  58.         return orderByClause;
  59.     }
  61.     /**
  62.      * This method was generated by MyBatis Generator.
  63.      * This method corresponds to the database table t_dept
  64.      *
  65.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  66.      */
  67.     public void setDistinct(boolean distinct) {
  68.         this.distinct = distinct;
  69.     }
  71.     /**
  72.      * This method was generated by MyBatis Generator.
  73.      * This method corresponds to the database table t_dept
  74.      *
  75.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  76.      */
  77.     public boolean isDistinct() {
  78.         return distinct;
  79.     }
  81.     /**
  82.      * This method was generated by MyBatis Generator.
  83.      * This method corresponds to the database table t_dept
  84.      *
  85.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  86.      */
  87.     public List<Criteria> getOredCriteria() {
  88.         return oredCriteria;
  89.     }
  91.     /**
  92.      * This method was generated by MyBatis Generator.
  93.      * This method corresponds to the database table t_dept
  94.      *
  95.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  96.      */
  97.     public void or(Criteria criteria) {
  98.         oredCriteria.add(criteria);
  99.     }
  101.     /**
  102.      * This method was generated by MyBatis Generator.
  103.      * This method corresponds to the database table t_dept
  104.      *
  105.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  106.      */
  107.     public Criteria or() {
  108.         Criteria criteria = createCriteriaInternal();
  109.         oredCriteria.add(criteria);
  110.         return criteria;
  111.     }
  113.     /**
  114.      * This method was generated by MyBatis Generator.
  115.      * This method corresponds to the database table t_dept
  116.      *
  117.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  118.      */
  119.     public Criteria createCriteria() {
  120.         Criteria criteria = createCriteriaInternal();
  121.         if (oredCriteria.size() == 0) {
  122.             oredCriteria.add(criteria);
  123.         }
  124.         return criteria;
  125.     }
  127.     /**
  128.      * This method was generated by MyBatis Generator.
  129.      * This method corresponds to the database table t_dept
  130.      *
  131.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  132.      */
  133.     protected Criteria createCriteriaInternal() {
  134.         Criteria criteria = new Criteria();
  135.         return criteria;
  136.     }
  138.     /**
  139.      * This method was generated by MyBatis Generator.
  140.      * This method corresponds to the database table t_dept
  141.      *
  142.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  143.      */
  144.     public void clear() {
  145.         oredCriteria.clear();
  146.         orderByClause = null;
  147.         distinct = false;
  148.     }
  150.     /**
  151.      * This class was generated by MyBatis Generator.
  152.      * This class corresponds to the database table t_dept
  153.      *
  154.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  155.      */
  156.     protected abstract static class GeneratedCriteria {
  157.         protected List<Criterion> criteria;
  159.         protected GeneratedCriteria() {
  160.             super();
  161.             criteria = new ArrayList<Criterion>();
  162.         }
  164.         public boolean isValid() {
  165.             return criteria.size() > 0;
  166.         }
  168.         public List<Criterion> getAllCriteria() {
  169.             return criteria;
  170.         }
  172.         public List<Criterion> getCriteria() {
  173.             return criteria;
  174.         }
  176.         protected void addCriterion(String condition) {
  177.             if (condition == null) {
  178.                 throw new RuntimeException("Value for condition cannot be null");
  179.             }
  180.             criteria.add(new Criterion(condition));
  181.         }
  183.         protected void addCriterion(String condition, Object value, String property) {
  184.             if (value == null) {
  185.                 throw new RuntimeException("Value for " + property + " cannot be null");
  186.             }
  187.             criteria.add(new Criterion(condition, value));
  188.         }
  190.         protected void addCriterion(String condition, Object value1, Object value2, String property) {
  191.             if (value1 == null || value2 == null) {
  192.                 throw new RuntimeException("Between values for " + property + " cannot be null");
  193.             }
  194.             criteria.add(new Criterion(condition, value1, value2));
  195.         }
  197.         public Criteria andDeptIdIsNull() {
  198.             addCriterion("dept_id is null");
  199.             return (Criteria) this;
  200.         }
  202.         public Criteria andDeptIdIsNotNull() {
  203.             addCriterion("dept_id is not null");
  204.             return (Criteria) this;
  205.         }
  207.         public Criteria andDeptIdEqualTo(Integer value) {
  208.             addCriterion("dept_id =", value, "deptId");
  209.             return (Criteria) this;
  210.         }
  212.         public Criteria andDeptIdNotEqualTo(Integer value) {
  213.             addCriterion("dept_id <>", value, "deptId");
  214.             return (Criteria) this;
  215.         }
  217.         public Criteria andDeptIdGreaterThan(Integer value) {
  218.             addCriterion("dept_id >", value, "deptId");
  219.             return (Criteria) this;
  220.         }
  222.         public Criteria andDeptIdGreaterThanOrEqualTo(Integer value) {
  223.             addCriterion("dept_id >=", value, "deptId");
  224.             return (Criteria) this;
  225.         }
  227.         public Criteria andDeptIdLessThan(Integer value) {
  228.             addCriterion("dept_id <", value, "deptId");
  229.             return (Criteria) this;
  230.         }
  232.         public Criteria andDeptIdLessThanOrEqualTo(Integer value) {
  233.             addCriterion("dept_id <=", value, "deptId");
  234.             return (Criteria) this;
  235.         }
  237.         public Criteria andDeptIdIn(List<Integer> values) {
  238.             addCriterion("dept_id in", values, "deptId");
  239.             return (Criteria) this;
  240.         }
  242.         public Criteria andDeptIdNotIn(List<Integer> values) {
  243.             addCriterion("dept_id not in", values, "deptId");
  244.             return (Criteria) this;
  245.         }
  247.         public Criteria andDeptIdBetween(Integer value1, Integer value2) {
  248.             addCriterion("dept_id between", value1, value2, "deptId");
  249.             return (Criteria) this;
  250.         }
  252.         public Criteria andDeptIdNotBetween(Integer value1, Integer value2) {
  253.             addCriterion("dept_id not between", value1, value2, "deptId");
  254.             return (Criteria) this;
  255.         }
  257.         public Criteria andDeptNameIsNull() {
  258.             addCriterion("dept_name is null");
  259.             return (Criteria) this;
  260.         }
  262.         public Criteria andDeptNameIsNotNull() {
  263.             addCriterion("dept_name is not null");
  264.             return (Criteria) this;
  265.         }
  267.         public Criteria andDeptNameEqualTo(String value) {
  268.             addCriterion("dept_name =", value, "deptName");
  269.             return (Criteria) this;
  270.         }
  272.         public Criteria andDeptNameNotEqualTo(String value) {
  273.             addCriterion("dept_name <>", value, "deptName");
  274.             return (Criteria) this;
  275.         }
  277.         public Criteria andDeptNameGreaterThan(String value) {
  278.             addCriterion("dept_name >", value, "deptName");
  279.             return (Criteria) this;
  280.         }
  282.         public Criteria andDeptNameGreaterThanOrEqualTo(String value) {
  283.             addCriterion("dept_name >=", value, "deptName");
  284.             return (Criteria) this;
  285.         }
  287.         public Criteria andDeptNameLessThan(String value) {
  288.             addCriterion("dept_name <", value, "deptName");
  289.             return (Criteria) this;
  290.         }
  292.         public Criteria andDeptNameLessThanOrEqualTo(String value) {
  293.             addCriterion("dept_name <=", value, "deptName");
  294.             return (Criteria) this;
  295.         }
  297.         public Criteria andDeptNameLike(String value) {
  298.             addCriterion("dept_name like", value, "deptName");
  299.             return (Criteria) this;
  300.         }
  302.         public Criteria andDeptNameNotLike(String value) {
  303.             addCriterion("dept_name not like", value, "deptName");
  304.             return (Criteria) this;
  305.         }
  307.         public Criteria andDeptNameIn(List<String> values) {
  308.             addCriterion("dept_name in", values, "deptName");
  309.             return (Criteria) this;
  310.         }
  312.         public Criteria andDeptNameNotIn(List<String> values) {
  313.             addCriterion("dept_name not in", values, "deptName");
  314.             return (Criteria) this;
  315.         }
  317.         public Criteria andDeptNameBetween(String value1, String value2) {
  318.             addCriterion("dept_name between", value1, value2, "deptName");
  319.             return (Criteria) this;
  320.         }
  322.         public Criteria andDeptNameNotBetween(String value1, String value2) {
  323.             addCriterion("dept_name not between", value1, value2, "deptName");
  324.             return (Criteria) this;
  325.         }
  326.     }
  328.     /**
  329.      * This class was generated by MyBatis Generator.
  330.      * This class corresponds to the database table t_dept
  331.      *
  332.      * @mbggenerated do_not_delete_during_merge Thu Jul 06 11:01:56 CST 2023
  333.      */
  334.     public static class Criteria extends GeneratedCriteria {
  336.         protected Criteria() {
  337.             super();
  338.         }
  339.     }
  341.     /**
  342.      * This class was generated by MyBatis Generator.
  343.      * This class corresponds to the database table t_dept
  344.      *
  345.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  346.      */
  347.     public static class Criterion {
  348.         private String condition;
  350.         private Object value;
  352.         private Object secondValue;
  354.         private boolean noValue;
  356.         private boolean singleValue;
  358.         private boolean betweenValue;
  360.         private boolean listValue;
  362.         private String typeHandler;
  364.         public String getCondition() {
  365.             return condition;
  366.         }
  368.         public Object getValue() {
  369.             return value;
  370.         }
  372.         public Object getSecondValue() {
  373.             return secondValue;
  374.         }
  376.         public boolean isNoValue() {
  377.             return noValue;
  378.         }
  380.         public boolean isSingleValue() {
  381.             return singleValue;
  382.         }
  384.         public boolean isBetweenValue() {
  385.             return betweenValue;
  386.         }
  388.         public boolean isListValue() {
  389.             return listValue;
  390.         }
  392.         public String getTypeHandler() {
  393.             return typeHandler;
  394.         }
  396.         protected Criterion(String condition) {
  397.             super();
  398.             this.condition = condition;
  399.             this.typeHandler = null;
  400.             this.noValue = true;
  401.         }
  403.         protected Criterion(String condition, Object value, String typeHandler) {
  404.             super();
  405.             this.condition = condition;
  406.             this.value = value;
  407.             this.typeHandler = typeHandler;
  408.             if (value instanceof List<?>) {
  409.                 this.listValue = true;
  410.             } else {
  411.                 this.singleValue = true;
  412.             }
  413.         }
  415.         protected Criterion(String condition, Object value) {
  416.             this(condition, value, null);
  417.         }
  419.         protected Criterion(String condition, Object value, Object secondValue, String typeHandler) {
  420.             super();
  421.             this.condition = condition;
  422.             this.value = value;
  423.             this.secondValue = secondValue;
  424.             this.typeHandler = typeHandler;
  425.             this.betweenValue = true;
  426.         }
  428.         protected Criterion(String condition, Object value, Object secondValue) {
  429.             this(condition, value, secondValue, null);
  430.         }
  431.     }
  432. }

11.6.4.4、mapper接口生成内容示例

  1. package org.rain.mybatis.mapper;
  3. import java.util.List;
  4. import org.apache.ibatis.annotations.Param;
  5. import org.rain.mybatis.pojo.Dept;
  6. import org.rain.mybatis.pojo.DeptExample;
  8. public interface DeptMapper {
  9.     /**
  10.      * This method was generated by MyBatis Generator.
  11.      * This method corresponds to the database table t_dept
  12.      *
  13.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  14.      */
  15.     int countByExample(DeptExample example);
  17.     /**
  18.      * This method was generated by MyBatis Generator.
  19.      * This method corresponds to the database table t_dept
  20.      *
  21.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  22.      */
  23.     int deleteByExample(DeptExample example);
  25.     /**
  26.      * This method was generated by MyBatis Generator.
  27.      * This method corresponds to the database table t_dept
  28.      *
  29.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  30.      */
  31.     int deleteByPrimaryKey(Integer deptId);
  33.     /**
  34.      * This method was generated by MyBatis Generator.
  35.      * This method corresponds to the database table t_dept
  36.      *
  37.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  38.      */
  39.     int insert(Dept record);
  41.     /**
  42.      * This method was generated by MyBatis Generator.
  43.      * This method corresponds to the database table t_dept
  44.      *
  45.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  46.      */
  47.     int insertSelective(Dept record);
  49.     /**
  50.      * This method was generated by MyBatis Generator.
  51.      * This method corresponds to the database table t_dept
  52.      *
  53.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  54.      */
  55.     List<Dept> selectByExample(DeptExample example);
  57.     /**
  58.      * This method was generated by MyBatis Generator.
  59.      * This method corresponds to the database table t_dept
  60.      *
  61.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  62.      */
  63.     Dept selectByPrimaryKey(Integer deptId);
  65.     /**
  66.      * This method was generated by MyBatis Generator.
  67.      * This method corresponds to the database table t_dept
  68.      *
  69.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  70.      */
  71.     int updateByExampleSelective(@Param("record") Dept record, @Param("example") DeptExample example);
  73.     /**
  74.      * This method was generated by MyBatis Generator.
  75.      * This method corresponds to the database table t_dept
  76.      *
  77.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  78.      */
  79.     int updateByExample(@Param("record") Dept record, @Param("example") DeptExample example);
  81.     /**
  82.      * This method was generated by MyBatis Generator.
  83.      * This method corresponds to the database table t_dept
  84.      *
  85.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  86.      */
  87.     int updateByPrimaryKeySelective(Dept record);
  89.     /**
  90.      * This method was generated by MyBatis Generator.
  91.      * This method corresponds to the database table t_dept
  92.      *
  93.      * @mbggenerated Thu Jul 06 11:01:56 CST 2023
  94.      */
  95.     int updateByPrimaryKey(Dept record);
  96. }

11.6.4.5、映射文件生成内容示例

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
  3. <mapper namespace="org.rain.mybatis.mapper.DeptMapper" >
  4.   <resultMap id="BaseResultMap" type="org.rain.mybatis.pojo.Dept" >
  5.     <!--
  6.       WARNING - @mbggenerated
  7.       This element is automatically generated by MyBatis Generator, do not modify.
  8.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  9.     -->
  10.     <id column="dept_id" property="deptId" jdbcType="INTEGER" />
  11.     <result column="dept_name" property="deptName" jdbcType="VARCHAR" />
  12.   </resultMap>
  13.   <sql id="Example_Where_Clause" >
  14.     <!--
  15.       WARNING - @mbggenerated
  16.       This element is automatically generated by MyBatis Generator, do not modify.
  17.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  18.     -->
  19.     <where >
  20.       <foreach collection="oredCriteria" item="criteria" separator="or" >
  21.         <if test="criteria.valid" >
  22.           <trim prefix="(" suffix=")" prefixOverrides="and" >
  23.             <foreach collection="criteria.criteria" item="criterion" >
  24.               <choose >
  25.                 <when test="criterion.noValue" >
  26.                   and ${criterion.condition}
  27.                 </when>
  28.                 <when test="criterion.singleValue" >
  29.                   and ${criterion.condition} #{criterion.value}
  30.                 </when>
  31.                 <when test="criterion.betweenValue" >
  32.                   and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
  33.                 </when>
  34.                 <when test="criterion.listValue" >
  35.                   and ${criterion.condition}
  36.                   <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
  37.                     #{listItem}
  38.                   </foreach>
  39.                 </when>
  40.               </choose>
  41.             </foreach>
  42.           </trim>
  43.         </if>
  44.       </foreach>
  45.     </where>
  46.   </sql>
  47.   <sql id="Update_By_Example_Where_Clause" >
  48.     <!--
  49.       WARNING - @mbggenerated
  50.       This element is automatically generated by MyBatis Generator, do not modify.
  51.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  52.     -->
  53.     <where >
  54.       <foreach collection="example.oredCriteria" item="criteria" separator="or" >
  55.         <if test="criteria.valid" >
  56.           <trim prefix="(" suffix=")" prefixOverrides="and" >
  57.             <foreach collection="criteria.criteria" item="criterion" >
  58.               <choose >
  59.                 <when test="criterion.noValue" >
  60.                   and ${criterion.condition}
  61.                 </when>
  62.                 <when test="criterion.singleValue" >
  63.                   and ${criterion.condition} #{criterion.value}
  64.                 </when>
  65.                 <when test="criterion.betweenValue" >
  66.                   and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
  67.                 </when>
  68.                 <when test="criterion.listValue" >
  69.                   and ${criterion.condition}
  70.                   <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
  71.                     #{listItem}
  72.                   </foreach>
  73.                 </when>
  74.               </choose>
  75.             </foreach>
  76.           </trim>
  77.         </if>
  78.       </foreach>
  79.     </where>
  80.   </sql>
  81.   <sql id="Base_Column_List" >
  82.     <!--
  83.       WARNING - @mbggenerated
  84.       This element is automatically generated by MyBatis Generator, do not modify.
  85.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  86.     -->
  87.     dept_id, dept_name
  88.   </sql>
  89.   <select id="selectByExample" resultMap="BaseResultMap" parameterType="org.rain.mybatis.pojo.DeptExample" >
  90.     <!--
  91.       WARNING - @mbggenerated
  92.       This element is automatically generated by MyBatis Generator, do not modify.
  93.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  94.     -->
  95.     select
  96.     <if test="distinct" >
  97.       distinct
  98.     </if>
  99.     <include refid="Base_Column_List" />
  100.     from t_dept
  101.     <if test="_parameter != null" >
  102.       <include refid="Example_Where_Clause" />
  103.     </if>
  104.     <if test="orderByClause != null" >
  105.       order by ${orderByClause}
  106.     </if>
  107.   </select>
  108.   <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
  109.     <!--
  110.       WARNING - @mbggenerated
  111.       This element is automatically generated by MyBatis Generator, do not modify.
  112.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  113.     -->
  114.     select
  115.     <include refid="Base_Column_List" />
  116.     from t_dept
  117.     where dept_id = #{deptId,jdbcType=INTEGER}
  118.   </select>
  119.   <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
  120.     <!--
  121.       WARNING - @mbggenerated
  122.       This element is automatically generated by MyBatis Generator, do not modify.
  123.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  124.     -->
  125.     delete from t_dept
  126.     where dept_id = #{deptId,jdbcType=INTEGER}
  127.   </delete>
  128.   <delete id="deleteByExample" parameterType="org.rain.mybatis.pojo.DeptExample" >
  129.     <!--
  130.       WARNING - @mbggenerated
  131.       This element is automatically generated by MyBatis Generator, do not modify.
  132.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  133.     -->
  134.     delete from t_dept
  135.     <if test="_parameter != null" >
  136.       <include refid="Example_Where_Clause" />
  137.     </if>
  138.   </delete>
  139.   <insert id="insert" parameterType="org.rain.mybatis.pojo.Dept" >
  140.     <!--
  141.       WARNING - @mbggenerated
  142.       This element is automatically generated by MyBatis Generator, do not modify.
  143.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  144.     -->
  145.     insert into t_dept (dept_id, dept_name)
  146.     values (#{deptId,jdbcType=INTEGER}, #{deptName,jdbcType=VARCHAR})
  147.   </insert>
  148.   <insert id="insertSelective" parameterType="org.rain.mybatis.pojo.Dept" >
  149.     <!--
  150.       WARNING - @mbggenerated
  151.       This element is automatically generated by MyBatis Generator, do not modify.
  152.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  153.     -->
  154.     insert into t_dept
  155.     <trim prefix="(" suffix=")" suffixOverrides="," >
  156.       <if test="deptId != null" >
  157.         dept_id,
  158.       </if>
  159.       <if test="deptName != null" >
  160.         dept_name,
  161.       </if>
  162.     </trim>
  163.     <trim prefix="values (" suffix=")" suffixOverrides="," >
  164.       <if test="deptId != null" >
  165.         #{deptId,jdbcType=INTEGER},
  166.       </if>
  167.       <if test="deptName != null" >
  168.         #{deptName,jdbcType=VARCHAR},
  169.       </if>
  170.     </trim>
  171.   </insert>
  172.   <select id="countByExample" parameterType="org.rain.mybatis.pojo.DeptExample" resultType="java.lang.Integer" >
  173.     <!--
  174.       WARNING - @mbggenerated
  175.       This element is automatically generated by MyBatis Generator, do not modify.
  176.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  177.     -->
  178.     select count(*) from t_dept
  179.     <if test="_parameter != null" >
  180.       <include refid="Example_Where_Clause" />
  181.     </if>
  182.   </select>
  183.   <update id="updateByExampleSelective" parameterType="map" >
  184.     <!--
  185.       WARNING - @mbggenerated
  186.       This element is automatically generated by MyBatis Generator, do not modify.
  187.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  188.     -->
  189.     update t_dept
  190.     <set >
  191.       <if test="record.deptId != null" >
  192.         dept_id = #{record.deptId,jdbcType=INTEGER},
  193.       </if>
  194.       <if test="record.deptName != null" >
  195.         dept_name = #{record.deptName,jdbcType=VARCHAR},
  196.       </if>
  197.     </set>
  198.     <if test="_parameter != null" >
  199.       <include refid="Update_By_Example_Where_Clause" />
  200.     </if>
  201.   </update>
  202.   <update id="updateByExample" parameterType="map" >
  203.     <!--
  204.       WARNING - @mbggenerated
  205.       This element is automatically generated by MyBatis Generator, do not modify.
  206.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  207.     -->
  208.     update t_dept
  209.     set dept_id = #{record.deptId,jdbcType=INTEGER},
  210.       dept_name = #{record.deptName,jdbcType=VARCHAR}
  211.     <if test="_parameter != null" >
  212.       <include refid="Update_By_Example_Where_Clause" />
  213.     </if>
  214.   </update>
  215.   <update id="updateByPrimaryKeySelective" parameterType="org.rain.mybatis.pojo.Dept" >
  216.     <!--
  217.       WARNING - @mbggenerated
  218.       This element is automatically generated by MyBatis Generator, do not modify.
  219.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  220.     -->
  221.     update t_dept
  222.     <set >
  223.       <if test="deptName != null" >
  224.         dept_name = #{deptName,jdbcType=VARCHAR},
  225.       </if>
  226.     </set>
  227.     where dept_id = #{deptId,jdbcType=INTEGER}
  228.   </update>
  229.   <update id="updateByPrimaryKey" parameterType="org.rain.mybatis.pojo.Dept" >
  230.     <!--
  231.       WARNING - @mbggenerated
  232.       This element is automatically generated by MyBatis Generator, do not modify.
  233.       This element was generated on Thu Jul 06 11:01:56 CST 2023.
  234.     -->
  235.     update t_dept
  236.     set dept_name = #{deptName,jdbcType=VARCHAR}
  237.     where dept_id = #{deptId,jdbcType=INTEGER}
  238.   </update>
  239. </mapper>

11.7、测试示例

11.7.1、引入相关配置文件

11.7.1.1、jdbc.properties

  1. jdbc.driver=com.mysql.jdbc.Driver
  2. jdbc.url=jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8
  3. jdbc.username=root
  4. jdbc.password=root

11.7.1.2、mybatis-config.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE configuration
  3.         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  4.         "http://mybatis.org/dtd/mybatis-3-config.dtd">
  6. <configuration>
  8.     <properties resource="jdbc.properties"/>
  10.     <settings>
  11.         <!--将下划线映射为驼峰-->
  12.         <setting name="mapUnderscoreToCamelCase" value="true"/>
  13.         <!--开启延迟加载-->
  14.         <!--<setting name="lazyLoadingEnabled" value="true"/>-->
  15.         <!--开启二级缓存-->
  16.         <setting name="cacheEnabled" value="true"/>
  17.     </settings>
  19.     <typeAliases>
  20.         <package name="org.rain.mybatis.pojo"/>
  21.     </typeAliases>
  23.     <environments default="development">
  25.         <environment id="development">
  26.             <transactionManager type="JDBC"/>
  27.             <dataSource type="POOLED">
  28.                 <property name="driver" value="${jdbc.driver}"/>
  29.                 <property name="url" value="${jdbc.url}"/>
  30.                 <property name="username" value="${jdbc.username}"/>
  31.                 <property name="password" value="${jdbc.password}"/>
  32.             </dataSource>
  33.         </environment>
  34.     </environments>
  36.     <mappers>
  37.         <package name="org.rain.mybatis.mapper"/>
  38.     </mappers>
  40. </configuration>

11.7.1.3、log4j.xml

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
  3. <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
  4.     <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
  5.         <param name="Encoding" value="UTF-8" />
  6.         <layout class="org.apache.log4j.PatternLayout">
  7.             <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
  8.         </layout>
  9.     </appender>
  10.     <logger name="java.sql">
  11.         <level value="debug" />
  12.     </logger>
  13.     <logger name="org.apache.ibatis">
  14.         <level value="info" />
  15.     </logger>
  16.     <root>
  17.         <level value="debug" />
  18.         <appender-ref ref="STDOUT" />
  19.     </root>
  20. </log4j:configuration>

11.7.2、创建获取SqlSession工具类

  1. package org.rain.mybatis.utils;
  3. import org.apache.ibatis.io.Resources;
  4. import org.apache.ibatis.session.SqlSession;
  5. import org.apache.ibatis.session.SqlSessionFactory;
  6. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  8. import java.io.IOException;
  9. import java.io.InputStream;
  11. public class SqlSessionUtils {
  12.     public static SqlSession getSqlSession(){
  13.         SqlSession sqlSession = null;
  15.         try {
  16.             //读取MyBatis核心配置文件的输入流
  17.             InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
  18.             //创建SqlSessionFactoryBuilder对象
  19.             SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
  20.             //通过核心配置文件所对应的字节输入流创建工厂类SqlSessionFactory，用于生产SqlSession对象
  21.             SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
  22.             //创建自动提交事务的SqlSession对象
  23.             sqlSession = sqlSessionFactory.openSession(true);
  24.         } catch (IOException e) {
  25.             e.printStackTrace();
  26.         }
  27.         return sqlSession;
  28.     }
  29. }

11.7.3、创建测试类

11.7.4、根据主键查询一条数据

注意：生成的实体类没有tostring方法，因此需要手动在实体类添加tostring方法才有相关输出

  1.     @Test
  2.     public void testMbg(){
  3.         SqlSession sqlSession = SqlSessionUtils.getSqlSession();
  4.         EmpMapper empMapper = sqlSession.getMapper(EmpMapper.class);
  6.         //根据主键查询一条数据
  7.         Emp emp = empMapper.selectByPrimaryKey(1);
  8.         System.out.println(emp);
  10.     }

11.7.5、查询所有数据

注意：无条件查询（即xxxExample为null）就是查询所有

  1.     @Test
  2.     public void testMbg(){
  3.         SqlSession sqlSession = SqlSessionUtils.getSqlSession();
  4.         EmpMapper empMapper = sqlSession.getMapper(EmpMapper.class);
  6.         //查询所有数据
  7.         List<Emp> emps = empMapper.selectByExample(null);
  8.         for (Emp emp : emps) {
  9.             System.out.println(emp);
  10.         }
  12.     }

11.7.6、多条件查询(QBC风格)

  1.     @Test
  2.     public void testMbg(){
  3.         SqlSession sqlSession = SqlSessionUtils.getSqlSession();
  4.         EmpMapper empMapper = sqlSession.getMapper(EmpMapper.class);
  6.         //多条件查询，QBC（query by condition）风格
  7.         EmpExample empExample = new EmpExample();
  8.         empExample.createCriteria().andEmpNameEqualTo("小红").andEmpIdBetween(8,10);
  9.         empExample.or().andAgeEqualTo(20);
  10.         List<Emp> emps = empMapper.selectByExample(empExample);
  11.         for (Emp emp : emps) {
  12.             System.out.println(emp);
  13.         }
  15.     }

11.7.7、普通修改

++++++++++++++++++++++++分割线++++++++++++++++++++++++

++++++++++++++++++++++++分割线++++++++++++++++++++++++

注意：如图所示，普通修改会将显式设置为null或未设置的字段都修改为null

  1.     @Test
  2.     public void testMbg(){
  3.         SqlSession sqlSession = SqlSessionUtils.getSqlSession();
  4.         EmpMapper empMapper = sqlSession.getMapper(EmpMapper.class);
  6.         Emp emp = new Emp();
  7.         emp.setEmpId(4);
  8.         emp.setEmpName("小军");
  9.         emp.setAge(null);
  10.         emp.setGender("女");
  11.         empMapper.updateByPrimaryKey(emp);
  12.     }

11.7.8、选择性修改

++++++++++++++++++++++++分割线++++++++++++++++++++++++

++++++++++++++++++++++++分割线++++++++++++++++++++++++

注意：如图所示，选择性修改不会将显式设置为null或未设置的字段修改为null

  1.     @Test
  2.     public void testMbg(){
  3.         SqlSession sqlSession = SqlSessionUtils.getSqlSession();
  4.         EmpMapper empMapper = sqlSession.getMapper(EmpMapper.class);
  6.         Emp emp = new Emp();
  7.         emp.setEmpId(3);
  8.         emp.setEmpName("小军");
  9.         emp.setAge(null);
  10.         emp.setGender("女");
  11.         empMapper.updateByPrimaryKeySelective(emp);
  12.     }

11、Mybatis之逆向工程的更多相关文章

  1. mybatis学习系列四--mybatis generator逆向工程

    采用命令行方式执行逆向工程 1.配置文件generatorConfig.xml 保存在目录:D:\E\workspace\eclipse\mybatis_generator <?xmlversi ...

  2. 创建mybatis的逆向工程

    1.mybatis的逆向工程(我使用的是maven仓库创建) 工作原理:反向工程(通过数据库中的表和字段信息去生成对应的增删改查方法) 其实就是一个自动生成工具 生成实体类(pojo)和映射文件(ma ...

  3. mybatis的逆向工程

    mybatis的逆向工程是很大的减少了程序员对代码的编写工作,由于mybatis是半自动的sql语句使用,我们在项目中一般都是采用逆向工程来生成mybatis的文件,mapper接口相当于我们平常所说 ...

  4. Mybatis(七) mybatis的逆向工程的配置详解

    还是觉得看书学习有意思~嘿嘿.今天把mybatis给结束掉. --WH 一.什么是逆向工程? 简单点说,就是通过数据库中的单表,自动生成java代码. Mybatis官方提供了逆向工程,可以针对单表自 ...

  5. Mybatis【逆向工程，缓存，代理】知识要点

    前言 本文主要讲解Mybatis的以下知识点: Mybatis缓存 一级缓存 二级缓存 与Ehcache整合 Mapper代理 使用Mapper代理就不用写实现类了 逆向工程 自动生成代码 Mybat ...

  6. Mybatis学习（七）————— mybatis的逆向工程的配置详解

    一.什么是逆向工程? 简单点说,就是通过数据库中的单表,自动生成java代码. Mybatis官方提供了逆向工程,可以针对单表自动生成mybatis代码(mapper.java\mapper.xml\ ...

  7. SpringBoot+Mybatis+Generator 逆向工程使用（二）

    Mybatis-Genarator 逆向工程使用 个人开发环境 java环境:Jdk1.8.0_60 编译器:IntelliJ IDEA 2017.1.4 mysql驱动:mysql-connecto ...

  8. 【MyBatis学习15】MyBatis的逆向工程生成代码

    1. 什么是逆向工程 mybatis的一个主要的特点就是需要程序员自己编写sql,那么如果表太多的话,难免会很麻烦,所以mybatis官方提供了一个逆向工程,可以针对单表自动生成mybatis执行所需 ...

  9. Mybatis的逆向工程以及Example的实例函数及详解

    Mybatis-generator是Mybatis的逆向工程  (根据数据库中的表生成java代码) Mybatis的逆向工程会生成实例及实例对应的example,example用于添加条件,相当于w ...

  10. Mybatis Generator逆向工程的使用

    一.在 idea 中使用 mybatis generator 逆向工程 1.在IDEA上创建maven工程. 2.在pom.xml中配置MyBatis逆向工程插件 <!--MyBatis自动生成 ...

随机推荐

  1. ue全家桶进阶之路30：Vue3定义组件和常用指令

    要定义 Vue 3 组件,你可以使用 Vue 3 提供的 defineComponent 函数. 例如,以下是一个简单的 Vue 3 组件定义: import { defineComponent } ...

  2. 2023-05-20：go语言的slice和rust语言的Vec的扩容流程是什么？

    2023-05-20:go语言的slice和rust语言的Vec的扩容流程是什么? 答案2023-05-20: go语言的slice扩容流程 go版本是1.20.4. 扩容流程见源码见runtime/ ...

  3. 计算机网络OSI七层参考模型和tcp/udp五层参考模型

    计算机网络OSI七层参考模型和tcp/udp五层参考模型 目录 一.OSI七层参考模型和TCP/UDP五层参考模型 1.应用层 2.表示层 3.会话层 4.传输层 5.网络层 6.数据链路层 7.物理 ...

  4. < Python全景系列-8 > Python超薄感知，超强保护：异常处理的绝佳实践

    欢迎来到我们的系列博客<Python全景系列>!在这个系列中,我们将带领你从Python的基础知识开始,一步步深入到高级话题,帮助你掌握这门强大而灵活的编程语法.无论你是编程新手,还是有一 ...

  5. Java（数组使用、Arrays、稀疏数组）

    1.数组的使用 For-Each循环 int[] arrays = {1,2,3,4,5}; //打印全部的数组元素 JDK1.5 没有下标 for (int array : arrays) { Sy ...

  6. Hive执行计划之hive依赖及权限查询和常见使用场景

    目录 概述 1.explain dependency的查询与使用 2.借助explain dependency解决一些常见问题 2.1.识别看似等价的SQL代码实际上是不等价的: 2.2 通过expl ...

  7. Spring Boot 通用对象列表比较和去重

    1.前言   在Excel批量导入数据时,常常需要与数据库中已存在数据的比较,并且需要考虑导入数据重复的可能性.   导入的行数据,一般有一个实体类(对象)与之对应,往往这个实体类在数据库中的字段要比 ...

  8. Rust的类型系统

    Rust的类型系统 类型于20世纪50年代被FORTRAN语言引入,其相关的理论和应用已经发展得非常成熟.现在,类型系统已经成为了各大编程语言的核心基础. 通用基础 所谓类型,就是对表示信息的值进行的 ...

  9. 300行代码模拟cdn

    这一生听过许多道理,但还是过不好这一生,这是因为缺少真正的动手实践,光听道理,缺少动手实践的过程,学习难免会让人觉得味同嚼蜡,所以我的分享都比较倾向于实践,在一次次动手实践的过程中感受知识原本纯真的模 ...

  10. go使用 github.com/influxdata/influxdb/client/v2 写数据到 influxdb

    转载请注明出处: 接入示例 使用 github.com/influxdata/influxdb/client/v2 依赖包向 InfluxDB 写入数据的示例代码: package main impo ...