mybatis generator配置

前言

​ 每次做完一些配置都会忘，都要回去看博客，mybatis-generator的配置算是比较麻烦的了，但是配好之后用起来很方便，什么mapper，xml、model一键生成，几乎也不用自己写sql语句，爽的飞起，所以必须记录一下。

​ 官方文档

步骤

​ 首先确保你已经在pom文件中添加了mybatis的相关依赖。

1.pom文件中添加plugin，在里面添加数据库相关驱动

<plugin>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.3.7</version>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.16</version>
        </dependency>
    </dependencies>
</plugin>

​ 我使用的是myssql数据库，所以添加的mysql的驱动

2. 在resources下，创建generatorConfig.xml文件

3.配置generatorCofig.xml文件

官网示例文件

<?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="DB2Tables" targetRuntime="MyBatis3">
        <plugin type="org.mybatis.generator.plugins.RowBoundsPlugin"></plugin>
        <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
                        connectionURL="jdbc:mysql://localhost/community?serverTimezone=GMT"
                        userId="root"
                        password="******">
            <property name="nullCatalogMeansCurrent" value="true"/>
        </jdbcConnection>

        <javaTypeResolver >
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <javaModelGenerator targetPackage="cpsky.community.model" targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <sqlMapGenerator targetPackage="mapper"  targetProject="src/main/resources">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>

        <javaClientGenerator type="XMLMAPPER" targetPackage="cpsky.community.mapper"  targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

        <table tableName="user" domainObjectName="User" ></table>
        <table tableName="question" domainObjectName="Question" ></table>
        <table tableName="comment" domainObjectName="Comment"></table>
    </context>
</generatorConfiguration>

<jdbcConnection>填写你的数据库有关信息 <javaModelGenerator>生成java模型（配好路径）

<sqlMapperGenerator>生成mapper.xml文件（可以修改生成方式 如注释等）

详见

<javaClientGenerator>生成mapper层

<table>对应数据库的表

4.配置跟springboot相关联

官网说明

启动类添加@MapperScan(mapper层路径如com.***.mapper)

application.properties添加mybatis.mapper-locations=classpath:mapper/*.xml

application.properties添加mybatis.type-aliases-package=com.example.domain.model

5.在终端运行命令

mvn -Dmybatis.generator.overwrite=true mybatis-generator:generate

​ overwrite默认覆盖原先已经存在的文件

6.自定义查询语句

​ 因为overwirte=true 会覆盖原文件，所以要新建.xml文件和对应的mapper接口。举个例子：

<?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="cpsky.community.mapper.CommentExtMapper">
    <resultMap id="BaseResultMap" type="cpsky.community.model.Comment">
        <!--
          WARNING - @mbg.generated
          This element is automatically generated by MyBatis Generator, do not modify.
          This element was generated on Sat Jun 08 11:39:52 CST 2019.
        -->
        <id column="id" jdbcType="BIGINT" property="id"/>
        <result column="parent_id" jdbcType="BIGINT" property="parentId"/>
        <result column="type" jdbcType="INTEGER" property="type"/>
        <result column="commentator" jdbcType="BIGINT" property="commentator"/>
        <result column="gmt_create" jdbcType="BIGINT" property="gmtCreate"/>
        <result column="gmt_modified" jdbcType="BIGINT" property="gmtModified"/>
        <result column="like_count" jdbcType="BIGINT" property="likeCount"/>
        <result column="content" jdbcType="VARCHAR" property="content"/>
        <result column="comment_count" jdbcType="INTEGER" property="commentCount"/>
    </resultMap>
    <update id="incCommentCount" parameterType="cpsky.community.model.Comment">
        update COMMENT
        set comment_count = comment_count + #{commentCount,jdbcType=INTEGER}
        where id = #{id}
    </update>
</mapper>

​ 要修改的有namespace ，以及curd语句，语法就是mybatis的语法辣，对应的Mapper接口长这个样子：

public interface CommentExtMapper {
    int incCommentCount(Comment comment);
}