相信很多朋友在项目中使用的ORM框架都是MyBatis，如果单用MyBatis来操作数据库的话，需要手写很多单表查询的SQL实现。这时候我们往往会选择一个增强工具来实现这些单表CRUD操作，这里推荐一款好用的工具MyBatis-Plus！

MyBatis-Plus简介

MyBatis-Plus(简称 MP)是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。MyBatis-Plus 提供了代码生成器，可以一键生成controller、service、mapper、model、mapper.xml代码，同时提供了丰富的CRUD操作方法，助我们解放双手！

MyBatis-Plus集成首先我们需要在SpringBoot项目中集成MyBatis-Plus，之后我们再详细介绍它的使用方法！在pom.xml中添加相关依赖，主要是MyBatis-Plus、MyBatis-Plus Generator和Velocity模板引擎；

com.baomidou

mybatis-plus-boot-starter

3.3.2

com.baomidou

mybatis-plus-generator

3.3.2

org.apache.velocity

velocity-engine-core

2.2

在SpringBoot配置文件application.yml添加如下配置，配置好数据源和MyBatis-Plus；spring:

datasource:

url: jdbc:mysql://localhost:3306/mall?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai

username: root

password: root

mybatis-plus:

mapper-locations: classpath:/mapper/**/*.xml #指定mapper.xml路径

global-config:

db-config:

id-type: auto #全局默认主键类型设置为自增

configuration:

auto-mapping-behavior: partial #只对非嵌套的 resultMap 进行自动映射

map-underscore-to-camel-case: true #开启自动驼峰命名规则映射添加MyBatis-Plus的Java配置，使用@MapperScan注解配置好需要扫码的Mapper接口路径，MyBatis-Plus自带分页功能，需要配置好分页插件PaginationInterceptor。/**

* MyBatis配置类

* Created by macro on 2019/4/8.

*/

@Configuration

@MapperScan("com.macro.mall.tiny.modules.*.mapper")

public class MyBatisConfig {

@Bean

public PaginationInterceptor paginationInterceptor() {

PaginationInterceptor paginationInterceptor = new PaginationInterceptor();

paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));

return paginationInterceptor;

}

}

代码生成器MyBatis-Plus 提供了代码生成器，可以一键生成controller、service、mapper、model、mapper.xml代码，非常方便！首先我们创建代码生成器类MyBatisPlusGenerator，直接运行其main方法即可生成相关代码；/**

* MyBatisPlus代码生成器

* Created by macro on 2020/8/20.

*/

public class MyBatisPlusGenerator {

public static void main(String[] args) {

String projectPath = System.getProperty("user.dir") + "/mall-tiny-plus";

String moduleName = scanner("模块名");

String[] tableNames = scanner("表名，多个英文逗号分割").split(",");

// 代码生成器

AutoGenerator autoGenerator = new AutoGenerator();

autoGenerator.setGlobalConfig(initGlobalConfig(projectPath));

autoGenerator.setDataSource(initDataSourceConfig());

autoGenerator.setPackageInfo(initPackageConfig(moduleName));

autoGenerator.setCfg(initInjectionConfig(projectPath, moduleName));

autoGenerator.setTemplate(initTemplateConfig());

autoGenerator.setStrategy(initStrategyConfig(tableNames));

autoGenerator.setTemplateEngine(new VelocityTemplateEngine());

autoGenerator.execute();

}

/**

* 读取控制台内容信息

*/

private static String scanner(String tip) {

Scanner scanner = new Scanner(System.in);

System.out.println(("请输入" + tip + "："));

if (scanner.hasNext()) {

String next = scanner.next();

if (StrUtil.isNotEmpty(next)) {

return next;

}

}

throw new MybatisPlusException("请输入正确的" + tip + "！");

}

/**

* 初始化全局配置

*/

private static GlobalConfig initGlobalConfig(String projectPath) {

GlobalConfig globalConfig = new GlobalConfig();

globalConfig.setOutputDir(projectPath + "/src/main/java");

globalConfig.setAuthor("macro");

globalConfig.setOpen(false);

globalConfig.setSwagger2(true);

globalConfig.setBaseResultMap(true);

globalConfig.setFileOverride(true);

globalConfig.setDateType(DateType.ONLY_DATE);

globalConfig.setEntityName("%s");

globalConfig.setMapperName("%sMapper");

globalConfig.setXmlName("%sMapper");

globalConfig.setServiceName("%sService");

globalConfig.setServiceImplName("%sServiceImpl");

globalConfig.setControllerName("%sController");

return globalConfig;

}

/**

* 初始化数据源配置

*/

private static DataSourceConfig initDataSourceConfig() {

Props props = new Props("generator.properties");

DataSourceConfig dataSourceConfig = new DataSourceConfig();

dataSourceConfig.setUrl(props.getStr("dataSource.url"));

dataSourceConfig.setDriverName(props.getStr("dataSource.driverName"));

dataSourceConfig.setUsername(props.getStr("dataSource.username"));

dataSourceConfig.setPassword(props.getStr("dataSource.password"));

return dataSourceConfig;

}

/**

* 初始化包配置

*/

private static PackageConfig initPackageConfig(String moduleName) {

Props props = new Props("generator.properties");

PackageConfig packageConfig = new PackageConfig();

packageConfig.setModuleName(moduleName);

packageConfig.setParent(props.getStr("package.base"));

packageConfig.setEntity("model");

return packageConfig;

}

/**

* 初始化模板配置

*/

private static TemplateConfig initTemplateConfig() {

TemplateConfig templateConfig = new TemplateConfig();

//可以对controller、service、entity模板进行配置

//mapper.xml模板需单独配置

templateConfig.setXml(null);

return templateConfig;

}

/**

* 初始化策略配置

*/

private static StrategyConfig initStrategyConfig(String[] tableNames) {

StrategyConfig strategyConfig = new StrategyConfig();

strategyConfig.setNaming(NamingStrategy.underline_to_camel);

strategyConfig.setColumnNaming(NamingStrategy.underline_to_camel);

strategyConfig.setEntityLombokModel(true);

strategyConfig.setRestControllerStyle(true);

//当表名中带*号时可以启用通配符模式

if (tableNames.length == 1 && tableNames[0].contains("*")) {

String[] likeStr = tableNames[0].split("_");

String likePrefix = likeStr[0] + "_";

strategyConfig.setLikeTable(new LikeTable(likePrefix));

} else {

strategyConfig.setInclude(tableNames);

}

return strategyConfig;

}

/**

* 初始化自定义配置

*/

private static InjectionConfig initInjectionConfig(String projectPath, String moduleName) {

// 自定义配置

InjectionConfig injectionConfig = new InjectionConfig() {

@Override

public void initMap() {

// 可用于自定义属性

}

};

// 模板引擎是Velocity

String templatePath = "/templates/mapper.xml.vm";

// 自定义输出配置

List focList = new ArrayList<>();

// 自定义配置会被优先输出

focList.add(new FileOutConfig(templatePath) {

@Override

public String outputFile(TableInfo tableInfo) {

// 自定义输出文件名 ， 如果你 Entity 设置了前后缀、此处注意 xml 的名称会跟着发生变化！！

return projectPath + "/src/main/resources/mapper/" + moduleName

+ "/" + tableInfo.getEntityName() + "Mapper" + StringPool.DOT_XML;

}

});

injectionConfig.setFileOutConfigList(focList);

return injectionConfig;

}

}然后在resources目录下添加配置文件generator.properties，添加代码生成器的数据源配置及存放业务代码的基础包名称；dataSource.url=jdbc:mysql://localhost:3306/mall?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai

dataSource.driverName=com.mysql.cj.jdbc.Driver

dataSource.username=root

dataSource.password=root

package.base=com.macro.mall.tiny.modules细心的朋友可以发现MyBatisPlusGenerator中很多配置代码都没添加注释，其实MyBatis-Plus源码中的中文注释非常完善，只需查看源码即可，这里摘抄一段DataSourceConfig中的源码；/**

* 数据库配置

*

* @author YangHu, hcl

* @since 2016/8/30

*/

@Data

@Accessors(chain = true)

public class DataSourceConfig {

/**

* 数据库信息查询

*/

private IDbQuery dbQuery;

/**

* 数据库类型

*/

private DbType dbType;

/**

* PostgreSQL schemaName

*/

private String schemaName;

/**

* 类型转换

*/

private ITypeConvert typeConvert;

/**

* 关键字处理器

* @since 3.3.2

*/

private IKeyWordsHandler keyWordsHandler;

/**

* 驱动连接的URL

*/

private String url;

/**

* 驱动名称

*/

private String driverName;

/**

* 数据库连接用户名

*/

private String username;

/**

* 数据库连接密码

*/

private String password;

//省略若干代码......

}代码生成器支持两种模式，一种生成单表的代码，比如只生成pms_brand表代码可以先输入pms，后输入pms_brand；

生成单表代码结构一览；

另一种直接生成整个模块的代码，需要带通配符*，比如生成ums模块代码可以先输入ums，后输入ums_*；

生成整个模块代码结构一览。

自定义生成模板MyBatis-Plus 使用模板引擎来生成代码，支持 Velocity(默认)、Freemarker、Beetl模板引擎，这里以Velocity为了来介绍下如何自定义生成模板。首先我们可以从 MyBatis-Plus Generator依赖包的源码中找到默认模板，拷贝到项目的resources/templates目录下；

在MyBatisPlusGenerator类中对TemplateConfig进行配置，配置好各个模板的路径；/**

* MyBatisPlus代码生成器

* Created by macro on 2020/8/20.

*/

public class MyBatisPlusGenerator {

/**

* 初始化模板配置

*/

private static TemplateConfig initTemplateConfig() {

TemplateConfig templateConfig = new TemplateConfig();

//可以对controller、service、entity模板进行配置

templateConfig.setEntity("templates/entity.java");

templateConfig.setMapper("templates/mapper.java");

templateConfig.setController("templates/controller.java");

templateConfig.setService("templates/service.java");

templateConfig.setServiceImpl("templates/serviceImpl.java");

//mapper.xml模板需单独配置

templateConfig.setXml(null);

return templateConfig;

}

}对模板进行定制，在定制过程中我们可以发现很多内置变量，用于输出到模板中去，这里以service.java.vm模板为例子，比如package、table这些变量；package ${package.Service};

import ${package.Entity}.${entity};

import ${superServiceClassPackage};

/**

*

* $!{table.comment} 服务类

*

*

* @author ${author}

* @since ${date}

*/

#if(${kotlin})

interface ${table.serviceName} : ${superServiceClass}

#else

public interface ${table.serviceName} extends ${superServiceClass} {

}

#end搞懂这些变量从哪来的，对我们定制模板很有帮助，其实这些变量都来着于AbstractTemplateEngine的getObjectMap方法，具体变量作用可以参考源码。/**

* 模板引擎抽象类

*

* @author hubin

* @since 2018-01-10

*/

public abstract class AbstractTemplateEngine {

/**

* 渲染对象 MAP 信息

*

* @param tableInfo 表信息对象

* @return ignore

*/

public Map getObjectMap(TableInfo tableInfo) {

Map objectMap = new HashMap<>(30);

ConfigBuilder config = getConfigBuilder();

if (config.getStrategyConfig().isControllerMappingHyphenStyle()) {

objectMap.put("controllerMappingHyphenStyle", config.getStrategyConfig().isControllerMappingHyphenStyle());

objectMap.put("controllerMappingHyphen", StringUtils.camelToHyphen(tableInfo.getEntityPath()));

}

objectMap.put("restControllerStyle", config.getStrategyConfig().isRestControllerStyle());

objectMap.put("config", config);

objectMap.put("package", config.getPackageInfo());

GlobalConfig globalConfig = config.getGlobalConfig();

objectMap.put("author", globalConfig.getAuthor());

objectMap.put("idType", globalConfig.getIdType() == null ? null : globalConfig.getIdType().toString());

objectMap.put("logicDeleteFieldName", config.getStrategyConfig().getLogicDeleteFieldName());

objectMap.put("versionFieldName", config.getStrategyConfig().getVersionFieldName());

objectMap.put("activeRecord", globalConfig.isActiveRecord());

objectMap.put("kotlin", globalConfig.isKotlin());

objectMap.put("swagger2", globalConfig.isSwagger2());

objectMap.put("date", new SimpleDateFormat("yyyy-MM-dd").format(new Date()));

objectMap.put("table", tableInfo);

objectMap.put("enableCache", globalConfig.isEnableCache());

objectMap.put("baseResultMap", globalConfig.isBaseResultMap());

objectMap.put("baseColumnList", globalConfig.isBaseColumnList());

objectMap.put("entity", tableInfo.getEntityName());

objectMap.put("entitySerialVersionUID", config.getStrategyConfig().isEntitySerialVersionUID());

objectMap.put("entityColumnConstant", config.getStrategyConfig().isEntityColumnConstant());

objectMap.put("entityBuilderModel", config.getStrategyConfig().isEntityBuilderModel());

objectMap.put("chainModel", config.getStrategyConfig().isChainModel());

objectMap.put("entityLombokModel", config.getStrategyConfig().isEntityLombokModel());

objectMap.put("entityBooleanColumnRemoveIsPrefix", config.getStrategyConfig().isEntityBooleanColumnRemoveIsPrefix());

objectMap.put("superEntityClass", getSuperClassName(config.getSuperEntityClass()));

objectMap.put("superMapperClassPackage", config.getSuperMapperClass());

objectMap.put("superMapperClass", getSuperClassName(config.getSuperMapperClass()));

objectMap.put("superServiceClassPackage", config.getSuperServiceClass());

objectMap.put("superServiceClass", getSuperClassName(config.getSuperServiceClass()));

objectMap.put("superServiceImplClassPackage", config.getSuperServiceImplClass());

objectMap.put("superServiceImplClass", getSuperClassName(config.getSuperServiceImplClass()));

objectMap.put("superControllerClassPackage", verifyClassPacket(config.getSuperControllerClass()));

objectMap.put("superControllerClass", getSuperClassName(config.getSuperControllerClass()));

return Objects.isNull(config.getInjectionConfig()) ? objectMap : config.getInjectionConfig().prepareObjectMap(objectMap);

}

}

CRUD操作MyBatis-Plus的强大之处不止在于它的代码生成功能，还在于它提供了丰富的CRUD方法，让我们实现单表CRUD几乎不用手写SQL实现！我们之前生成的PmsBrandMapper接口由于继承了BaseMapper接口，直接拥有了各种CRUD方法；/**

*

* 品牌表 Mapper 接口

*

*

* @author macro

* @since 2020-08-20

*/

public interface PmsBrandMapper extends BaseMapper {

}我们来看下BaseMapper中的方法，是不是基本可以满足我们的日常所需了；

我们之前生成的PmsBrandService接口由于继承了IService接口，也拥有了各种CRUD方法；/**

*

* 品牌表 服务类

*

*

* @author macro

* @since 2020-08-20

*/

public interface PmsBrandService extends IService {

}可以看下比BaseMapper中的更加丰富；

有了这些IService和BaseMapper中提供的这些方法，我们单表查询就几乎不用手写SQL实现了，使用MyBatis-Plus实现以前PmsBrandController的方法更轻松了！/**

*

* 品牌表 前端控制器

*

*

* @author macro

* @since 2020-08-20

*/

@Api(tags = "PmsBrandController", description = "商品品牌管理")

@RestController

@RequestMapping("/brand")

public class PmsBrandController {

private static final Logger LOGGER = LoggerFactory.getLogger(PmsBrandController.class);

@Autowired

private PmsBrandService brandService;

@ApiOperation("获取所有品牌列表")

@RequestMapping(value = "/listAll", method = RequestMethod.GET)

@ResponseBody

public CommonResult> getBrandList() {

return CommonResult.success(brandService.list());

}

@ApiOperation("添加品牌")

@RequestMapping(value = "/create", method = RequestMethod.POST)

@ResponseBody

public CommonResult createBrand(@RequestBody PmsBrand pmsBrand) {

CommonResult commonResult;

boolean result = brandService.save(pmsBrand);

if (result) {

commonResult = CommonResult.success(pmsBrand);

LOGGER.debug("createBrand success:{}", pmsBrand);

} else {

commonResult = CommonResult.failed("操作失败");

LOGGER.debug("createBrand failed:{}", pmsBrand);

}

return commonResult;

}

@ApiOperation("更新指定id品牌信息")

@RequestMapping(value = "/update", method = RequestMethod.POST)

@ResponseBody

public CommonResult updateBrand(@RequestBody PmsBrand pmsBrand) {

CommonResult commonResult;

boolean result = brandService.updateById(pmsBrand);

if (result) {

commonResult = CommonResult.success(pmsBrand);

LOGGER.debug("updateBrand success:{}", pmsBrand);

} else {

commonResult = CommonResult.failed("操作失败");

LOGGER.debug("updateBrand failed:{}", pmsBrand);

}

return commonResult;

}

@ApiOperation("删除指定id的品牌")

@RequestMapping(value = "/delete/{id}", method = RequestMethod.GET)

@ResponseBody

public CommonResult deleteBrand(@PathVariable("id") Long id) {

boolean result = brandService.removeById(id);

if (result) {

LOGGER.debug("deleteBrand success :id={}", id);

return CommonResult.success(null);

} else {

LOGGER.debug("deleteBrand failed :id={}", id);

return CommonResult.failed("操作失败");

}

}

@ApiOperation("分页查询品牌列表")

@RequestMapping(value = "/list", method = RequestMethod.GET)

@ResponseBody

public CommonResult> listBrand(@RequestParam(value = "pageNum", defaultValue = "1")

@ApiParam("页码") Integer pageNum,

@RequestParam(value = "pageSize", defaultValue = "3")

@ApiParam("每页数量") Integer pageSize) {

Page page = new Page<>(pageNum, pageSize);

Page pageResult = brandService.page(page);

return CommonResult.success(CommonPage.restPage(pageResult));

}

@ApiOperation("获取指定id的品牌详情")

@RequestMapping(value = "/{id}", method = RequestMethod.GET)

@ResponseBody

public CommonResult brand(@PathVariable("id") Long id) {

return CommonResult.success(brandService.getById(id));

}

}

项目源码地址