Spring Boot项目中使用MyBatis Generator (MBG) 自动生成Mapper文件

Spring Boot项目中使用MyBatis Generator (MBG) 自动生成Mapper文件可以很大程度上减少编码。本文着重介绍如何在实战中使用MGB自动生成Mapper文件

1. 添加MyBatis Generator依赖

在pom.xml中添加必要的依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.3.1</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
    <version>8.0.28</version>
</dependency>

<dependency>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-core</artifactId>
    <version>1.3.7</version>
</dependency>



<plugin>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.4.0</version>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
        </dependency>
    </dependencies>
</plugin>

根据自需进行添加相关的依赖jar包。上面是基于MySQL，如果你是SQL Server或者别的数据库还需要自行引入相关依赖。如 SQL Server

<dependency>
    <groupId>com.microsoft.sqlserver</groupId>
    <artifactId>mssql-jdbc</artifactId>
</dependency>

2. 创建自动生成代码配置

在resource目录下创建generator.properties 和 generator-config.xml两个配置文件

① generator.properties：配置文件用来添加数据库连接信息 (可选择性创建)

② generator-config.xml：用于生成代码时指定生成的目录路径、代码函数

2.1 generator.properties

jdbc.driver-class=com.mysql.cj.jdbc.Driver
jdbc.connection.url=jdbc:mysql://localhost:3306/test_db?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=root123456

2.2 generator-config.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">

<generatorConfiguration>
<properties resource="generator.properties"/>
<context id="MySqlContext" targetRuntime="MyBatis3" defaultModelType="flat">
    <property name="beginningDelimiter" value="`"/>
    <property name="endingDelimiter" value="`"/>
    <property name="javaFileEncoding" value="UTF-8"/>
    <!-- 为模型生成序列化方法-->
    <plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>
    <!-- 为生成的Java模型创建一个toString方法 -->
    <plugin type="org.mybatis.generator.plugins.ToStringPlugin"/>
    <!--生成mapper.xml时覆盖原文件-->
    <plugin type="org.mybatis.generator.plugins.UnmergeableXmlMappersPlugin"/>
    <!--可以自定义生成代码注释-->
    <commentGenerator type="com.demo.example.utils.CommentGenerator">
        <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
        <property name="suppressAllComments" value="true"/>
        <property name="suppressDate" value="true"/>
        <property name="addRemarkComments" value="true"/>
    </commentGenerator>
    <!--配置数据库连接-->
    <jdbcConnection driverClass="${jdbc.driver-class}"
                    connectionURL="${jdbc.connection.url}"
                    userId="${jdbc.username}"
                    password="${jdbc.password}">
        <!--解决mysql驱动升级到8.0后不生成指定数据库代码的问题-->
        <property name="nullCatalogMeansCurrent" value="true"/>
    </jdbcConnection>
    <!--指定生成model的路径-->
    <javaModelGenerator targetPackage="com.demo.example.entity" targetProject="src\main\java"/>
    <!--指定生成mapper.xml的路径-->
    <sqlMapGenerator targetPackage="mappers" targetProject="src\main\resources"/>
    <!--指定生成mapper接口的的路径-->
    <javaClientGenerator type="XMLMAPPER" targetPackage="com.demo.example.mapper"
                         targetProject="src\main\java"/>
    <!--生成全部表tableName设为%-->
    <table tableName="table_name" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false"
           enableSelectByExample="false" selectByExampleQueryId="false">

        <property name="useActualColumnNames" value="false"/>
        <property name="constructorBased" value="false"/>
        <generatedKey column="id" sqlStatement="JDBC" identity="true"/>
    </table>

</context>
</generatorConfiguration>

3. 自定义备注添加器CommentGenerator

import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.Field;
import org.mybatis.generator.internal.DefaultCommentGenerator;
import org.mybatis.generator.internal.util.StringUtility;

import java.util.Properties;

/**
 * @author
 */
public class CommentGenerator extends DefaultCommentGenerator {
    private boolean addRemarkComments = false;

    
    @Override
    public void addConfigurationProperties(Properties properties) {
        super.addConfigurationProperties(properties);
        this.addRemarkComments = StringUtility.isTrue(properties.getProperty("addRemarkComments"));
    }

    
    @Override
    public void addFieldComment(Field field, IntrospectedTable introspectedTable,
                                IntrospectedColumn introspectedColumn) {
        String remarks = introspectedColumn.getRemarks();
        if (addRemarkComments && StringUtility.stringHasValue(remarks)) {
            addJavaDoc2Field(field, remarks);
        }
    }

    
    private void addJavaDoc2Field(Field field, String remarks) {
        
        field.addJavaDocLine("/**");
        String[] remarkLines = remarks.split(System.getProperty("line.separator"));
        for (String remarkLine : remarkLines) {
            field.addJavaDocLine(" * " + remarkLine);
        }
        addJavadocTag(field, false);
        field.addJavaDocLine(" */");
    }

}

我的CommentGenerator是创建在utils包下的，随意创建，只需要把第2步的commentGenerator标签中的type属性值替换一下

<commentGenerator type="替换成自己的包路径">

</commentGenerator>

4. 创建代码生成器 Generator

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

/**
 * @author
 * @description
 */
public class Generator {

    public static void main(String[] args) throws Exception {
        List<String> warnings = new ArrayList<>();
        boolean overwrite = true;
        //读配置文件
        InputStream is = Generator.class.getResourceAsStream("/generator-config.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(is);
        is.close();
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);
        for (String warning : warnings) {
            System.out.println(warning);
        }
    }
}

以上关于Spring Boot项目中使用MBG自动生成Mapper文件相关配置就介绍完了，最后只需要修改成指定的表名，执行Generator类的main方法就可以了