MyBatis逆向工程（代码生成器）

妖狐艹你老母 2022-09-14 03:00 166阅读 0赞

> 前言：本文简单介绍了MyBatis的逆向工程用法，介绍了两种启动方式和提供了关于MBG配置文件的样例。逆向工程通过数据库自动创建三个组件，减轻开发工作量，提高开发效率。

## 简介 ##

官方文档：[http://mybatis.org/generator/][http_mybatis.org_generator]

官方代码：[https://github.com/mybatis/generator][https_github.com_mybatis_generator]

MyBatis框架需要：实体类、自定义Mapper接口、Mapper.xml

传统的开发中上诉的三个组件需要开发者手动创建，逆向工程可以帮助开发者来自动创建三个组件，减轻开发工作量，提高开发效率

## maven插件启动方式（无需启动类） ##

### generator插件 ###

<properties>
        <mysql.connect.version>8.0.25</mysql.connect.version>
        <mybatis.generator.plugin.version>1.4.0</mybatis-plus.version>
        <mybatis.generator.vision>1.4.0</mybatis-plus.generator.vision>
    </properties>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>${mybatis.generator.plugin.version}</version>
                <configuration>
                    
                    <configurationFile>src/main/resources/generatorConfig.xml</configurationFile>
                    
                    <verbose>true</verbose>
                    
                    <overwrite>true</overwrite>
                </configuration>
                <executions>
                    <execution>
                        <id>Generate MyBatis Artifacts</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                    </execution>
                </executions>
                <dependencies>
                    
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>${mysql.connect.version}</version>
                    </dependency>
                    
                    <dependency>
                        <groupId>org.mybatis.generator</groupId>
                        <artifactId>mybatis-generator-core</artifactId>
                        <version>${mybatis.generator.version}/<version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>

## main启动方式（需启动类） ##

### 导入依赖 ###

<dependencies>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
        
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.2</version>
    	</dependency>
    </dependencies>

### 启动类 ###

`Generator`

public class Generator {
        
        public static void main(String[] args) throws InterruptedException, SQLException, IOException, XMLParserException, InvalidConfigurationException {
        
            List<String> warnings = new ArrayList<>();	// 执行过程中的警告信息
            boolean overwrite = true;	// 生成的代码重复时，覆盖原代码
            // 指定配置文件位置
            String projectPath = System.getProperty("user.dir"); // 获取当前项目路径
            String configFilePath = projectPath + "/src/main/resources/generatorConfig.xml"; //需修改
            File configFile = new File(configFilePath);
            ConfigurationParser cp = new ConfigurationParser(warnings);
            Configuration config = cp.parseConfiguration(configFile);
            DefaultShellCallback callback = new DefaultShellCallback(overwrite);
            // mybatis-generator-core依赖 1.3.6 后才有MyBatisGenerator类,需要jre1.8才能运行
            MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
            myBatisGenerator.generate(null);		// 执行生成代码
            warnings.forEach(System.out::println);	// 输出警告信息
        }
    }

## 创建MBG配置文件 ##

### 核心配置说明 ###

1.  `jdbcConnection`：配置数据库连接信息
2.  `javaModelGenerator`：配置JavaBean的生成策略
3.  `sqlMapGenerator`：配置SQL映射文件生成策略
4.  `javaClientGenerator`：配置Mapper接口的生成策略
5.  `table`：配置目标数据库
    
     *  `tableName`：表名
     *  `domainObjectName`：JavaBean类名

### 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">
    
    <generatorConfiguration>
        
        
    
        <context id="mysqlTables" targetRuntime="MyBatis3">
            
            <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                            connectionURL="jdbc:mysql://localhost:3306/数据库名?serverTimezone=UTC&useUnicode=true&useSSL=false&characterEncoding=utf8"
                            userId="root"
                            password="密码">
            </jdbcConnection>
            
            
            <javaTypeResolver>
                <property name="forceBigDecimals" value="false" />
            </javaTypeResolver>
    
            
            <javaModelGenerator targetPackage="com.mybatis.pojo" targetProject="./src/main/java">
                <property name="enableSubPackages" value="true"/>
                
                <property name="trimStrings" value="true" />
            </javaModelGenerator>
    
            
            <sqlMapGenerator targetPackage="com.mybatis.mapper"  targetProject="./src/main/resources">
                <property name="enableSubPackages" value="true"/>
            </sqlMapGenerator>
    
            
            <javaClientGenerator type="XMLMAPPER" targetPackage="com.mybatis.mapper"  targetProject="./src/main/java">
                <property name="enableSubPackages" value="true"/>
            </javaClientGenerator>
    
            
            <table tableName="m_user" domainObjectName="User"></table>
    
        </context>
    </generatorConfiguration>

参考资料来源：

[【极简入门】4小时学会MyBatis | 楠哥教你学Java][4_MyBatis _ _Java]

[http_mybatis.org_generator]: http://mybatis.org/generator/
[https_github.com_mybatis_generator]: https://github.com/mybatis/generator
[4_MyBatis _ _Java]: https://www.bilibili.com/video/BV1V7411w7VW?p=5