MyBatis Generator使用总结

介绍
具体使用
- 数据准备
- 插件引入
- 配置
- 条件构建讲解
- demo地址

介绍

MyBatis Generator （MBG）是 MyBatis 的代码生成器。它能够根据数据库表，自动生成 java 实体类、dao 层接口（mapper 接口）及mapper.xml文件。

具体使用

数据准备

创建数据库(8.0版本)mybatis，并添加一张表rbac_user，用于测试

CREATE TABLE `rbac_user` (`id` int NOT NULL AUTO_INCREMENT COMMENT '主鍵',`name` varchar(100) DEFAULT NULL COMMENT '用户名',`email` varchar(100) DEFAULT NULL COMMENT '邮箱',`nick_name` varchar(100) DEFAULT NULL COMMENT '昵称',`remark` varchar(100) DEFAULT NULL COMMENT '备注',`create_time` date DEFAULT NULL COMMENT '创建时间',`status` char(1) DEFAULT NULL COMMENT '状态',PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='用户表';

如图所示：
在这里插入图片描述

插件引入

创建一个SpringBoot项目这里使用的spring boot版本是2.1.3.RELEASE，将mybatis 插件引入

		  <!--SpringBoot通用依赖模块--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!--SpringBoot整合MyBatis--><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.2.2</version></dependency><!--MyBatis分页插件--><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.5</version></dependency><!--集成druid连接池--><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.2.9</version></dependency><!-- MyBatis 生成器 --><dependency><groupId>org.mybatis.generator</groupId><artifactId>mybatis-generator-core</artifactId><version>1.4.1</version></dependency><!--Mysql数据库驱动--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.15</version></dependency><!--springfox swagger官方Starter--><dependency><groupId>io.springfox</groupId><artifactId>springfox-swagger2</artifactId><version>2.9.2</version></dependency><dependency><groupId>io.springfox</groupId><artifactId>springfox-swagger-ui</artifactId><version>2.9.2</version></dependency>

配置

1、对项目的application.yml进行配置：

server:port: 8080spring:datasource:url: jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghaiusername: rootpassword: rootmvc:pathmatch:matching-strategy: ANT_PATH_MATCHERmybatis:mapper-locations:- classpath:dao/*.xmlconfiguration:# 下划线自动转驼峰map-underscore-to-camel-case: truelogging:level:root: infocom.sheep: debug

2、创建配置文件为generator.properties，添加数据库配置信息，用于代码生成器配置使用：

jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.connectionURL=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
jdbc.userId=root
jdbc.password=root

3、创建代码生成器配置文件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><properties resource="generator.properties"/><context id="MySqlContext" targetRuntime="MyBatis3" defaultModelType="flat"><!-- 配置SQL语句中的前置分隔符 --><property name="beginningDelimiter" value="`"/><!-- 配置SQL语句中的后置分隔符 --><property name="endingDelimiter" value="`"/><!-- 配置生成Java文件的编码 --><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" /><commentGenerator type="com.macro.mall.CommentGenerator"><!-- 是否阻止生成的注释 --><property name="suppressAllComments" value="true"/><!-- 是否阻止生成的注释包含时间戳 --><property name="suppressDate" value="true"/><!-- 是否添加数据库表的备注信息 --><property name="addRemarkComments" value="true"/></commentGenerator><!--配置数据库连接--><jdbcConnection driverClass="${jdbc.driverClass}"connectionURL="${jdbc.connectionURL}"userId="${jdbc.userId}"password="${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.sheep.mbg.model" targetProject="learn-mybatis\src\main\java"/><!--指定生成mapper.xml的路径--><sqlMapGenerator targetPackage="com.sheep..mbg.mapper" targetProject="learn-mybatis\src\main\resources"/><!--指定生成mapper接口的的路径--><javaClientGenerator type="XMLMAPPER" targetPackage="com.sheep.mbg.mapper" targetProject="learn-mybatis\src\main\java"/><!--配置需要生成的表，生成全部表tableName设为% 还可以指定统一前缀的表 如 rbac_% 表示所有rbac_开始的所有表--><table tableName="rbac_%"><generatedKey column="id" sqlStatement="MySql" identity="true"/></table></context>
</generatorConfiguration>

4、实际开发中，有的项目是需要接入swagger-ui的，所以字段注释就得自定义。建立一个注释自定义处理类CommentGenerator：

import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.CompilationUnit;
import org.mybatis.generator.api.dom.java.Field;
import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
import org.mybatis.generator.internal.DefaultCommentGenerator;
import org.mybatis.generator.internal.util.StringUtility;import java.util.Properties;/*** 自定义注释生成器*/
public class CommentGenerator extends DefaultCommentGenerator {private boolean addRemarkComments = false;private static final String EXAMPLE_SUFFIX = "Example";private static final String MAPPER_SUFFIX = "Mapper";private static final String API_MODEL_PROPERTY_FULL_CLASS_NAME = "io.swagger.annotations.ApiModelProperty";/*** 设置用户配置的参数*/@Overridepublic void addConfigurationProperties(Properties properties) {super.addConfigurationProperties(properties);this.addRemarkComments = StringUtility.isTrue(properties.getProperty("addRemarkComments"));}/*** 给字段添加注释*/@Overridepublic void addFieldComment(Field field, IntrospectedTable introspectedTable,IntrospectedColumn introspectedColumn) {String remarks = introspectedColumn.getRemarks();//根据参数和备注信息判断是否添加swagger注解信息if (addRemarkComments && StringUtility.stringHasValue(remarks)) {
//            addFieldJavaDoc(field, remarks);//数据库中特殊字符需要转义if (remarks.contains("\"")) {remarks = remarks.replace("\"", "'");}//给model的字段添加swagger注解field.addJavaDocLine("@ApiModelProperty(value = \"" + remarks + "\")");}}/*** 给model的字段添加注释*/private void addFieldJavaDoc(Field field, String remarks) {//文档注释开始field.addJavaDocLine("/**");//获取数据库字段的备注信息String[] remarkLines = remarks.split(System.getProperty("line.separator"));for (String remarkLine : remarkLines) {field.addJavaDocLine(" * " + remarkLine);}addJavadocTag(field, false);field.addJavaDocLine(" */");}@Overridepublic void addJavaFileComment(CompilationUnit compilationUnit) {super.addJavaFileComment(compilationUnit);//只在model中添加swagger注解类的导入if (!compilationUnit.getType().getFullyQualifiedName().contains(MAPPER_SUFFIX) && !compilationUnit.getType().getFullyQualifiedName().contains(EXAMPLE_SUFFIX)) {compilationUnit.addImportedType(new FullyQualifiedJavaType(API_MODEL_PROPERTY_FULL_CLASS_NAME));}}
}

5、添加运行类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;public class Generator {public static void main(String[] args) throws Exception {//MBG 执行过程中的警告信息List<String> warnings = new ArrayList<String>();//当生成的代码重复时，覆盖原代码boolean overwrite = true;//读取我们的 MBG 配置文件InputStream is = Generator.class.getResourceAsStream("/generatorConfig.xml");ConfigurationParser cp = new ConfigurationParser(warnings);Configuration config = cp.parseConfiguration(is);is.close();DefaultShellCallback callback = new DefaultShellCallback(overwrite);//创建 MBGMyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);//执行生成代码myBatisGenerator.generate(null);//输出警告信息for (String warning : warnings) {System.out.println(warning);}}
}

6、运行后看结果：图中的路径是与配置文件相对应的。若不存在也会自动创建目录

生成结果
7、可以看到model对象中的各个字段的注释。
在这里插入图片描述
8、还有另个自动生成的对象类：此对象是为了配合增删改查的条件构建用的。

9、看下生成的Mapper接口，这里生成了基本增删改查操作的接口，查询参数也应用了删改你的条件构建对象。
mapper
10、构建RbacUserService，RbacUserController。具体讲解下这个条件构建器如何使用：

public interface RbacUserService {List<RbacUser> listAllUser();int createUser(RbacUser user);int updateUser(Integer id, RbacUser user);int deleteUser(Integer id);List<RbacUser> listUser(int pageNum, int pageSize);RbacUser getUser(Integer id);
}

@Service
public class RbacUserServiceImpl implements RbacUserService {@Autowiredprivate RbacUserMapper userMapper;@Overridepublic List<RbacUser> listAllUser() {return userMapper.selectByExample(new RbacUserExample());}@Overridepublic int createUser(RbacUser user) {return userMapper.insert(user);}@Overridepublic int updateUser(Integer id, RbacUser user) {user.setId(id);return userMapper.updateByPrimaryKeySelective(user);}@Overridepublic int deleteUser(Integer id) {return userMapper.deleteByPrimaryKey(id);}@Overridepublic List<RbacUser> listUser(int pageNum, int pageSize) {PageHelper.startPage(pageNum, pageSize);return userMapper.selectByExample(new RbacUserExample());}@Overridepublic RbacUser getUser(Integer id) {return userMapper.selectByPrimaryKey(id);}
}

@Api("用户管理")
@Controller
@RequestMapping("/user")
public class RbacUserController {private static final Logger LOGGER = LoggerFactory.getLogger(RbacUserController.class);@Autowiredprivate RbacUserService userService;@ApiOperation("获取所有用户列表")@RequestMapping(value = "listAll", method = RequestMethod.GET)@ResponseBodypublic CommonResult<List<RbacUser>> getUserList() {return CommonResult.success(userService.listAllUser());}@ApiOperation("添加用户")@RequestMapping(value = "/create", method = RequestMethod.POST)@ResponseBodypublic CommonResult createUser(@RequestBody RbacUser user) {CommonResult commonResult;int count = userService.createUser(user);if (count == 1) {commonResult = CommonResult.success(user);LOGGER.debug("createUser success:{}", user);} else {commonResult = CommonResult.failed("操作失败");LOGGER.debug("createUser failed:{}", user);}return commonResult;}@ApiOperation("更新指定id用户信息")@RequestMapping(value = "/update/{id}", method = RequestMethod.POST)@ResponseBodypublic CommonResult updateUser(@PathVariable("id") Integer id, @RequestBody RbacUser user, BindingResult result) {CommonResult commonResult;int count = userService.updateUser(id, user);if (count == 1) {commonResult = CommonResult.success(user);LOGGER.debug("updateUser success:{}", user);} else {commonResult = CommonResult.failed("操作失败");LOGGER.debug("updateUser failed:{}", user);}return commonResult;}@ApiOperation("删除指定id的用户")@RequestMapping(value = "/delete/{id}", method = RequestMethod.GET)@ResponseBodypublic CommonResult deleteUser(@PathVariable("id") Integer id) {int count = userService.deleteUser(id);if (count == 1) {LOGGER.debug("deleteUser success :id={}", id);return CommonResult.success(null);} else {LOGGER.debug("deleteUser failed :id={}", id);return CommonResult.failed("操作失败");}}@ApiOperation("分页查询用户列表")@RequestMapping(value = "/list", method = RequestMethod.GET)@ResponseBodypublic CommonResult<CommonPage<RbacUser>> listUser(@RequestParam(value = "pageNum", defaultValue = "1") Integer pageNum, @RequestParam(value = "pageSize", defaultValue = "10") Integer pageSize) {List<RbacUser> brandList = userService.listUser(pageNum, pageSize);return CommonResult.success(CommonPage.restPage(brandList));}@ApiOperation("获取指定id的品牌详情")@RequestMapping(value = "/{id}", method = RequestMethod.GET)@ResponseBodypublic CommonResult<RbacUser> user(@PathVariable("id") Integer id) {return CommonResult.success(userService.getUser(id));}
}

11、controller中的返回结果进行了统一，代码如下，可以自行修改：

public interface IErrorCode {long getCode();String getMessage();
}

public enum ResultCode implements IErrorCode {SUCCESS(200, "操作成功"),FAILED(500, "操作失败"),VALIDATE_FAILED(404, "参数检验失败"),UNAUTHORIZED(401, "暂未登录或token已经过期"),FORBIDDEN(403, "没有相关权限");private long code;private String message;private ResultCode(long code, String message) {this.code = code;this.message = message;}public long getCode() {return code;}public String getMessage() {return message;}
}

public class CommonPage<T> {private Integer pageNum;private Integer pageSize;private Integer totalPage;private Long total;private List<T> list;/*** 将PageHelper分页后的list转为分页信息*/public static <T> CommonPage<T> restPage(List<T> list) {CommonPage<T> result = new CommonPage<T>();PageInfo<T> pageInfo = new PageInfo<T>(list);result.setTotalPage(pageInfo.getPages());result.setPageNum(pageInfo.getPageNum());result.setPageSize(pageInfo.getPageSize());result.setTotal(pageInfo.getTotal());result.setList(pageInfo.getList());return result;}public Integer getPageNum() {return pageNum;}public void setPageNum(Integer pageNum) {this.pageNum = pageNum;}public Integer getPageSize() {return pageSize;}public void setPageSize(Integer pageSize) {this.pageSize = pageSize;}public Integer getTotalPage() {return totalPage;}public void setTotalPage(Integer totalPage) {this.totalPage = totalPage;}public List<T> getList() {return list;}public void setList(List<T> list) {this.list = list;}public Long getTotal() {return total;}public void setTotal(Long total) {this.total = total;}
}

public class CommonResult<T> {private long code;private String message;private T data;protected CommonResult() {}protected CommonResult(long code, String message, T data) {this.code = code;this.message = message;this.data = data;}/*** 成功返回结果** @param data 获取的数据*/public static <T> CommonResult<T> success(T data) {return new CommonResult<T>(ResultCode.SUCCESS.getCode(), ResultCode.SUCCESS.getMessage(), data);}/*** 成功返回结果** @param data    获取的数据* @param message 提示信息*/public static <T> CommonResult<T> success(T data, String message) {return new CommonResult<T>(ResultCode.SUCCESS.getCode(), message, data);}/*** 失败返回结果** @param errorCode 错误码*/public static <T> CommonResult<T> failed(IErrorCode errorCode) {return new CommonResult<T>(errorCode.getCode(), errorCode.getMessage(), null);}/*** 失败返回结果** @param message 提示信息*/public static <T> CommonResult<T> failed(String message) {return new CommonResult<T>(ResultCode.FAILED.getCode(), message, null);}/*** 失败返回结果*/public static <T> CommonResult<T> failed() {return failed(ResultCode.FAILED);}/*** 参数验证失败返回结果*/public static <T> CommonResult<T> validateFailed() {return failed(ResultCode.VALIDATE_FAILED);}/*** 参数验证失败返回结果** @param message 提示信息*/public static <T> CommonResult<T> validateFailed(String message) {return new CommonResult<T>(ResultCode.VALIDATE_FAILED.getCode(), message, null);}/*** 未登录返回结果*/public static <T> CommonResult<T> unauthorized(T data) {return new CommonResult<T>(ResultCode.UNAUTHORIZED.getCode(), ResultCode.UNAUTHORIZED.getMessage(), data);}/*** 未授权返回结果*/public static <T> CommonResult<T> forbidden(T data) {return new CommonResult<T>(ResultCode.FORBIDDEN.getCode(), ResultCode.FORBIDDEN.getMessage(), data);}public long getCode() {return code;}public void setCode(long code) {this.code = code;}public String getMessage() {return message;}public void setMessage(String message) {this.message = message;}public T getData() {return data;}public void setData(T data) {this.data = data;}
}

@Configuration
@EnableSwagger2
public class Swagger2Config {@Beanpublic Docket createRestApi() {return new Docket(DocumentationType.SWAGGER_2).apiInfo(apiInfo()).select()//为当前包下controller生成API文档.apis(RequestHandlerSelectors.basePackage("com.sheep.controller")).paths(PathSelectors.any()).build();}private ApiInfo apiInfo() {return new ApiInfoBuilder().title("SwaggerUI演示").description("learn-mybatis").contact(new Contact("sheep", "", "123@qq.com")).version("1.0").build();}
}

12、运行服务：
在这里插入图片描述
13、访问 http://localhost:8080/swagger-ui.html

成功启动。

条件构建讲解

从上面可以看到MyBatis Generator (MBG) 为每个数据库表生成了一个对应的 Example 类。它主要用于生成动态 SQL 语句。

Example 类允许你构建复杂的 WHERE 子句，而无需直接在 mapper 文件中硬编码 SQL，它包含了很多用于构建 WHERE 子句的方法。每个方法都对应一个 SQL 比较运算符，比如 “=”, “<>”, “>”, “<”, “LIKE” 等。你可以动态地添加、修改或删除查询条件。使用 Example 类，你可以构建几乎任何类型的查询，包括带有 AND 和 OR 子句的查询，带有子查询的查询等。

在使用 Example 类时，你需要创建一个 Example 对象，然后通过调用该对象的 createCriteria() 方法创建一个 Criteria 对象。然后你可以在 Criteria 对象上调用各种方法来添加查询条件。

上面的案例基本上都没用到，下面我们就开始使用这个条件构建器：

上面的案例是查询的所有用户，我们基于这个进行条件查询。
在这里插入图片描述
比如对名字进行模糊查询：

Criteria 对象创建后，可以调用里面的各个接口进行构建参数，这个里面会对每个参数生成 “=”, “<>”, “>”, “<”, “LIKE” 的查询接口。如图所示是上面的接口详情：可以看到默认的情况，不会加%的
在这里插入图片描述
再看addCriterion,可以看到是往全局变量list中插入不同的条件构建对象。

看下查询语句拼接效果：