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
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<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
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<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
java
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=root1234562.2 generator-config.xml
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
java
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
XML
<commentGenerator type="替换成自己的包路径">
</commentGenerator>4. 创建代码生成器 Generator
java
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
可以看到执行的结果已经在相应的目录下创建了PO实体类、Mapper接口和*Mapper.xml文件
几乎常用的SQL都已经生成了
总结一下：上面代码几乎可以直接粘贴复制使用，需要自己修改的地方有一下几处：
