MybatisPlus---分页查询和代码生成器

第一步：创建好SpringBoot项目后先配置maven依赖（完整pom如下）

注意：1.启动类上要加注解@MapperScan("com.zk.*.mapper") // 扫码mapper类，把bean加入到spring容器管理

           2..pom中resources配置不可缺少

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<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">     <modelVersion>4.0.0</modelVersion>     <parent>         <groupId>org.springframework.boot</groupId>         <artifactId>spring-boot-starter-parent</artifactId>         <version>2.5.4</version>         <relativePath/> <!-- lookup parent from repository -->     </parent>     <groupId>com.zk</groupId>     <artifactId>mybatisplus</artifactId>     <version>0.0.1-SNAPSHOT</version>     <name>mybatisplus</name>     <description>Demo project for Spring Boot</description>     <properties>         <java.version>1.8</java.version>     </properties>     <dependencies>         <dependency>             <groupId>org.springframework.boot</groupId>             <artifactId>spring-boot-starter-web</artifactId>         </dependency>         <dependency>             <groupId>mysql</groupId>             <artifactId>mysql-connector-java</artifactId>             <scope>runtime</scope>         </dependency>         <dependency>             <groupId>org.projectlombok</groupId>             <artifactId>lombok</artifactId>             <optional>true</optional>         </dependency>         <!-- 这是mybatis-plus依赖 -->         <dependency>             <groupId>com.baomidou</groupId>             <artifactId>mybatis-plus-boot-starter</artifactId>             <version>3.1.1</version>         </dependency>         <!-- 这是mybatis-plus的代码自动生成器 -->         <dependency>             <groupId>com.baomidou</groupId>             <artifactId>mybatis-plus-generator</artifactId>             <version>3.1.1</version>         </dependency>         <!-- 这是模板引擎依赖 不可缺少-->         <dependency>             <groupId>org.freemarker</groupId>             <artifactId>freemarker</artifactId>             <version>2.3.30</version>         </dependency>     </dependencies>       <build>         <plugins>             <plugin>                 <groupId>org.springframework.boot</groupId>                 <artifactId>spring-boot-maven-plugin</artifactId>             </plugin>               <!-- 打包时去除test测试类 -->             <plugin>                 <groupId>org.apache.maven.plugins</groupId>                 <artifactId>maven-surefire-plugin</artifactId>                 <configuration>                     <skip>true</skip>                 </configuration>             </plugin>         </plugins>           <resources>             <!--自动生成时候generate插件找到包，使用mybatis generator插件生成代码时先注掉-->             <resource>                 <directory>lib</directory>                 <targetPath>BOOT-INF/lib/</targetPath>                 <includes>                     <include>**/*.jar</include>                 </includes>             </resource>               <!-- maven项目中src源代码下的xml等资源文件编译进classes文件夹，注意：如果没有这个，它会自动搜索resources下是否有mapper.xml文件，               如果没有就会报org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): 很重要 -->             <resource>                 <directory>src/main/java</directory>                 <includes>                     <include>**/*.xml</include>                 </includes>             </resource>               <!-- 把resources下的文件编译进classes文件夹 -->             <resource>                 <directory>src/main/resources</directory>                 <includes>                     <include>**/*.*</include>                 </includes>                 <filtering>false</filtering>             </resource>         </resources>       </build>   </project>

第二步：在application.yml添加mybatis-plus配置

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#mybatis: #  mapper-locations: classpath:com/mapper/xml/*.xml #注意：一定要对应mapper映射xml文件的所在路径 #  type-aliases-package: com.model # 注意：对应实体类的路径 #  configuration:  #打印sql #  log-impl: org.apache.ibatis.logging.stdout.StdOutImpl   mybatis-plus:   configuration:     map-underscore-to-camel-case: true     auto-mapping-behavior: full     log-impl: org.apache.ibatis.logging.stdout.StdOutImpl   mapper-locations: classpath*:com/zk/mybatisplus/**/*Mapper.xml   global-config:     # 关闭MP3.0自带的banner     banner: false     # 逻辑删除配置     db-config:       # 删除前       logic-not-delete-value: 1       # 删除后       logic-delete-value: 0

第三步：需要配置一下分页插件

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@Configuration public class MybatisPlusConfig {     /**      * 分页插件      */     @Bean     public PaginationInterceptor paginationInterceptor() {         return new PaginationInterceptor();     } }

第四步:config目录下创建PageFactory类

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public class PageFactory {     /**      * 创建默认分页page      */     public static Page page() {         HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder                 .getRequestAttributes()).getRequest();           //第几页         int pageNum = 1;         //每页多少条数据         int limit = 10;         if (StringUtils.isNotBlank(request.getParameter("pageNum"))) {             pageNum = Integer.valueOf(request.getParameter("pageNum"));         }         if (StringUtils.isNotBlank(request.getParameter("limit"))) {             limit = Integer.valueOf(request.getParameter("limit"));         }         return page(pageNum, limit);     }       /**      * 创建默认分页page      */     public static Page page(Integer pageNum, Integer limit) {         return new Page(pageNum, limit);     }       /**      * 创建默认分页page      */     public static Page resultPage(List<Object> list) {         Page page = page();         page.setRecords(list);         page.setTotal(list.size());         int totalPagesNum = (int) (page.getTotal() / page.getSize());         page.setPages((page.getTotal() % page.getSize() == 0) ? totalPagesNum : totalPagesNum + 1);         return page;     } }

第五步：配置mybatis-plus的代码生成器

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/**  * 代码生成器  */ public class GeneratorCodeConfig {       public static String scanner(String tip) {         Scanner scanner = new Scanner(System.in);         StringBuilder help = new StringBuilder();         help.append("请输入" + tip + "：");         System.out.println(help.toString());         if (scanner.hasNext()) {             String ipt = scanner.next();             if (StringUtils.isNotEmpty(ipt)) {                 return ipt;             }         }         throw new MybatisPlusException("请输入正确的" + tip + "！");     }       public static void main(String[] args) {         // 代码生成器         AutoGenerator mpg = new AutoGenerator();           // 全局配置         GlobalConfig gc = new GlobalConfig();         String projectPath = System.getProperty("user.dir");         gc.setOutputDir(projectPath + "/src/main/java");         gc.setAuthor("zk");         gc.setOpen(false);         //实体属性 Swagger2 注解         gc.setSwagger2(false);         gc.setFileOverride(true);//是否覆盖         gc.setActiveRecord(true);         gc.setEnableCache(false);// XML 二级缓存         gc.setBaseResultMap(true);// XML中的ResultMap标签         gc.setBaseColumnList(false);// XML标签         gc.setIdType(IdType.AUTO); //主键策略         gc.setDateType(DateType.ONLY_DATE);         // 自定义文件命名，注意 %s 会自动填充表实体属性！         gc.setControllerName("%sController");         gc.setServiceName("%sService");         gc.setServiceImplName("%sServiceImpl");         gc.setMapperName("%sMapper");         mpg.setGlobalConfig(gc);           // 数据源配置         DataSourceConfig dsc = new DataSourceConfig();         dsc.setUrl("jdbc:mysql://localhost:3306/user");         dsc.setDriverName("com.mysql.cj.jdbc.Driver");         dsc.setUsername("root");         dsc.setPassword("123456");         mpg.setDataSource(dsc);           // 包配置         PackageConfig pc = new PackageConfig();         // pc.setModuleName(scanner("自定义包名"));         pc.setParent("com");         pc.setController("zk.mybatisplus.controller");         pc.setEntity("zk.mybatisplus.model");         pc.setMapper("zk.mybatisplus.mapper");         pc.setService("zk.mybatisplus.service");         pc.setServiceImpl("zk.mybatisplus.service.impl");         pc.setXml("zk.mybatisplus.mapper.xml");         mpg.setPackageInfo(pc);           // 自定义配置         InjectionConfig cfg = new InjectionConfig() {             @Override             public void initMap() {                 // to do nothing             }         };           // 如果模板引擎是 freemarker          String templatePath = "/templates/mapper.xml.ftl";         // 如果模板引擎是 velocity         //String templatePath = "/templates/mapper.xml.vm";           // 自定义输出配置         List<FileOutConfig> 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/java/com/zk/mybatisplus/mapper/xml"                         + "/" + tableInfo.getEntityName() + "Mapper" + StringPool.DOT_XML;             }         });         System.out.println( pc.getModuleName());         /*         cfg.setFileCreate(new IFileCreate() {             @Override             public boolean isCreate(ConfigBuilder configBuilder, FileType fileType, String filePath) {                 // 判断自定义文件夹是否需要创建                 checkDir("调用默认方法创建的目录");                 return false;             }         });         */         cfg.setFileOutConfigList(focList);         mpg.setCfg(cfg);           // 配置模板         TemplateConfig templateConfig = new TemplateConfig();           // 配置自定义输出模板         //指定自定义模板路径，注意不要带上.ftl/.vm, 会根据使用的模板引擎自动识别         // templateConfig.setEntity("templates/entity2.java");         // templateConfig.setService();         // templateConfig.setController();           templateConfig.setXml(null);         mpg.setTemplate(templateConfig);           // 策略配置         StrategyConfig strategy = new StrategyConfig();         strategy.setNaming(NamingStrategy.underline_to_camel);         strategy.setColumnNaming(NamingStrategy.underline_to_camel);         strategy.setSuperEntityClass("com.baomidou.mybatisplus.extension.activerecord.Model");         strategy.setEntityLombokModel(true);         strategy.setRestControllerStyle(true);           strategy.setEntityLombokModel(true);         // 公共父类 //        strategy.setSuperControllerClass("com.baomidou.ant.common.BaseController");         // 写于父类中的公共字段 //        strategy.setSuperEntityColumns("id");         strategy.setInclude(scanner("表名，多个英文逗号分割").split(","));         strategy.setControllerMappingHyphenStyle(true);         strategy.setTablePrefix(pc.getModuleName() + "_");         mpg.setStrategy(strategy);         mpg.setTemplateEngine(new FreemarkerTemplateEngine());         mpg.execute();     } }

运行之后，输入表名，生成表对应的model,service等文件。

如果运行代码生成器报错Exception in thread “main” java.lang.NoClassDefFoundError: freemarker/template/Configuration

问题可能原因：使用spring-boot-starter-test依赖

解决方案：1.注释掉spring-boot-starter-test依赖

                  2.复制此配置类到test目录运行

第六步：代码案例测试

controller层 

注意：传入参数为pageNo和pageSize 所以在serviceImpl实现类里用的是PageFactory中第二个page方法，如果想用第一个page方法，传入参数名需和第一个page方法保持一致，并且参数不用写入方法中。

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@RestController @RequestMapping("/role") @Api(value = "角色管理", tags = "角色管理") public class TTenantRoleController {       @Resource     private TTenantRoleService service;       @RequestMapping(value = "/findRoleByPage", method = RequestMethod.POST)     @ApiOperation(value = "分页获取所有角色")     public IPage<TTenantRole> findRoleByPage(@ApiParam(name = "pageNo", value = "当前页")                                              @RequestParam(value = "pageNo", required = false, defaultValue = "1") Integer pageNo,                                              @ApiParam(name = "pageSize", value = "每一页数据个数")                                              @RequestParam(value = "pageSize", required = false, defaultValue = "5") Integer pageSize) {         return service.findRoleByPage(pageNo,pageSize);     } }

service层

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public interface TTenantRoleService extends IService<TTenantRole> {     IPage<TTenantRole> findRoleByPage(Integer pageNo,Integer pageSize); }

service实现层

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@Service public class TTenantRoleServiceImpl extends ServiceImpl<TTenantRoleMapper, TTenantRole> implements TTenantRoleService {     @Resource     private TTenantRoleMapper mapper;       @Override     public IPage<TTenantRole> findRoleByPage(Integer pageNo,Integer pageSize) {         LambdaQueryWrapper<TTenantRole> query = Wrappers.lambdaQuery();         query.eq(TTenantRole::getValid, "Y");         Page<TTenantRole> page = PageFactory.page(pageNo,pageSize);         IPage<TTenantRole> tTenantRoleIPage = mapper.selectPage(page, query);         return tTenantRoleIPage;     } }

mapper层

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1 2	public interface TTenantRoleMapper extends BaseMapper<TTenantRole> { }

启动项目，访问效果如下图：

 查询第一页数据，每页两条数据，总数据条数为3，到此分页完成。