Java：MyBatis Generator自动生成代码

2021-11-22 10:05:41

文档：http://mybatis.org/generator/index.html

依赖 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mouday</groupId>
    <artifactId>generator-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.5</version>
                <configuration>
                    <configurationFile>src/main/resources/generatorConfig.xml</configurationFile>
                    <verbose>true</verbose>
                    <overwrite>true</overwrite>
                </configuration>

                <dependencies>
                    <dependency>
                        <groupId>org.mybatis.generator</groupId>
                        <artifactId>mybatis-generator-core</artifactId>
                        <version>1.3.5</version>
                    </dependency>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>8.0.20</version>
                    </dependency>
                </dependencies>

            </plugin>
        </plugins>
    </build>

</project>

生成器配置 generatorConfig.xml

<?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">

<!-- 配置生成器 -->
<generatorConfiguration>

    <context id="default" targetRuntime="MyBatis3">

        <!-- jdbc的数据库连接 -->
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/data"
                        userId="root"
                        password="123456"/>

        <!-- Model模型生成器-->
        <javaModelGenerator targetPackage="com.mouday.demo.model" 
                            targetProject="src/main/java"/>

        <!-- Mapper映射文件-->
        <sqlMapGenerator targetPackage="com.mouday.demo.mapper" 
                         targetProject="src/main/java"/>

        <!-- Mapper接口-->
        <javaClientGenerator targetPackage="com.mouday.demo.mapper" 
                             targetProject="src/main/java"
                             type="XMLMAPPER"/>

        <table tableName="person"/>

    </context>

</generatorConfiguration>

参数说明

通用参数
targetPackage     指定包名
targetProject     指定路径

javaClientGenerator可选参数：
type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper对象
type="MIXEDMAPPER",生成基于注解的Java Model 和相应的Mapper对象
type="XMLMAPPER",生成SQLMap XML文件和独立的Mapper接口

# 执行代码生成
$ mvn mybatis-generator:generate

# 生成的文件
$ tree
.
├── mapper
│   ├── PersonMapper.java
│   └── PersonMapper.xml
└── model
    ├── Person.java
    └── PersonExample.java

查看生成的文件里边有很多无用的代码，可以通过进一步的配置来控制代码生成

<?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">

<!-- 配置生成器 -->
<generatorConfiguration>

    <context id="default" targetRuntime="MyBatis3">

        <!--创建class时，对注释进行控制-->
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!--注释掉这行可以解决生成重复xml代码-->
            <property name="suppressAllComments" value="true"/>
            <property name="javaFileEncoding" value="UTF-8"/>
        </commentGenerator>

        <!-- jdbc的数据库连接 -->
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost:3306/data"
                        userId="root"
                        password="123456">
        </jdbcConnection>

        <!-- 非必需，类型处理器，在数据库类型和java类型之间的转换控制 -->
        <javaTypeResolver>
            <!-- 是否使用BigDecimals，false可自动转化以下类型(Long Integer Short等) -->
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>

        <!-- Model模型生成器-->
        <javaModelGenerator targetPackage="com.mouday.demo.model"
                            targetProject="src/main/java">
            <!--是否允许子包，即targetPackage.schemaName.tableName-->
            <property name="enableSubPackages" value="true"/>
            <!-- 是否对类CHAR类型的列的数据进行trim操作 -->
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>

        <!-- Mapper映射文件-->
        <sqlMapGenerator targetPackage="com.mouday.demo.mapper"
                         targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>

        <!-- Mapper接口-->
        <javaClientGenerator type="XMLMAPPER"
                             targetPackage="com.mouday.demo.mapper"
                             targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>

        <!-- 要生成的表 tableName是数据库中的表名或视图名
        domainObjectName是实体类名-->
        <table tableName="person"
               domainObjectName="Person"
               enableCountByExample="false"
               enableUpdateByExample="false"
               enableDeleteByExample="false"
               enableSelectByExample="false"
               selectByExampleQueryId="false">
        </table>

    </context>

</generatorConfiguration>

生成的代码就简洁了不少

Person.java

package com.mouday.demo.model;

public class Person {
    private Integer id;

    private String name;

    private Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

PersonMapper.java

package com.mouday.demo.mapper;

import com.mouday.demo.model.Person;

public interface PersonMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(Person record);

    int insertSelective(Person record);

    Person selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(Person record);

    int updateByPrimaryKey(Person record);
}

PersonMapper.xml

<?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.mouday.demo.mapper.PersonMapper">
  <resultMap id="BaseResultMap" type="com.mouday.demo.model.Person">
    <id column="id" jdbcType="INTEGER" property="id" />
    <result column="name" jdbcType="VARCHAR" property="name" />
    <result column="age" jdbcType="INTEGER" property="age" />
  </resultMap>
  <sql id="Base_Column_List">
    id, name, age
  </sql>
  <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from person
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
    delete from person
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.mouday.demo.model.Person">
    insert into person (id, name, age
      )
    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER}
      )
  </insert>
  <insert id="insertSelective" parameterType="com.mouday.demo.model.Person">
    insert into person
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="id != null">
        id,
      </if>
      <if test="name != null">
        name,
      </if>
      <if test="age != null">
        age,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="id != null">
        #{id,jdbcType=INTEGER},
      </if>
      <if test="name != null">
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="age != null">
        #{age,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.mouday.demo.model.Person">
    update person
    <set>
      <if test="name != null">
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="age != null">
        age = #{age,jdbcType=INTEGER},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.mouday.demo.model.Person">
    update person
    set name = #{name,jdbcType=VARCHAR},
      age = #{age,jdbcType=INTEGER}
    where id = #{id,jdbcType=INTEGER}
  </update>
</mapper>

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