• Java 使用Velocity引擎生成代码

    Java 使用Velocity引擎生成代码

    原理

    •  

    • 配置数据源信息（包括表名）

    • 读取数据表字段信息：列名、类型、字段注释、表注释

    • 编写代码模板，并将该模板加载到内存

    • 根据模板所需，组装Velocity引擎渲染所需字段Map

    • 创建Velocity上下文，将代码模板和替换字段传入

    • velocity上下文创建引擎，执行merge合并替换并将最终代码写入文件

    实战

    • 通过maven构建项目，引入依赖：

      2.     velocity
      3.     org.apache.velocity
      4.     
      5.         
      6.             commons-collections
      7.             commons-collections
      8.         
      9.     
      12.     org.apache.velocity
      13.     velocity-engine-core

    • 在resources/templates/codegenerator目录下面编写代码模板：

    • vo:

      1. package ${basePackage}.module.${modulePackage}.domain.vo;
      2. ​
      3. import lombok.Data;
      4. #foreach ($dtoImport in $dtoImports)
      5. $dtoImport
      6. #end
      7. import com.fasterxml.jackson.annotation.JsonFormat;
      8. import io.swagger.annotations.ApiModelProperty;
      9. ​
      10. /**
      11.  *  [ ${tableDesc} ]
      12.  *
      13.  * @author ${author}
      14.  * @version 1.0
      15.  * @company ${company}
      16.  * @copyright (c) ${company}Inc. All rights reserved.
      17.  * @date  ${date}
      18.  * @since JDK1.8
      19.  */
      20. @Data
      21. public class ${moduleClass}VO {
      22. #foreach ($column in $columnList)
      23. #if($column.fieldType == 'Date')
      24.     @ApiModelProperty("${column.columnDesc}")
      25.     @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
      26.     private $column.fieldType $column.fieldName;
      27. #else
      28.     @ApiModelProperty("${column.columnDesc}")
      29.     private $column.fieldType $column.fieldName;
      30. #end
      31. ​
      32. #end
      33. }

    • SERVICE:

      1. package ${basePackage}.module.${modulePackage}.service;
      2. ​
      3. import com.baomidou.mybatisplus.core.metadata.IPage;
      4. import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
      5. import ${basePackage}.common.domain.PageResultDTO;
      6. import ${basePackage}.common.domain.ResponseDTO;
      7. import ${basePackage}.module.${modulePackage}.dao.${moduleClass}Dao;
      8. import ${basePackage}.module.${modulePackage}.domain.dto.${moduleClass}AddDTO;
      9. import ${basePackage}.module.${modulePackage}.domain.dto.${moduleClass}UpdateDTO;
      10. import ${basePackage}.module.${modulePackage}.domain.dto.${moduleClass}QueryDTO;
      11. import ${basePackage}.module.${modulePackage}.domain.entity.${moduleClass}Entity;
      12. import ${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}VO;
      13. import ${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}ExcelVO;
      14. import ${basePackage}.util.SmartPageUtil;
      15. import ${basePackage}.util.SmartBeanUtil;
      16. import org.springframework.beans.factory.annotation.Autowired;
      17. import org.springframework.stereotype.Service;
      18. import org.springframework.transaction.annotation.Transactional;
      19. ​
      20. import java.util.List;
      21. ​
      22. /**
      23.  * [ ${tableDesc} ]
      24.  *
      25.  * @author ${author}
      26.  * @version 1.0
      27.  * @company ${company}
      28.  * @copyright (c)  ${company}Inc. All rights reserved.
      29.  * @date ${date}
      30.  * @since JDK1.8
      31.  */
      32. @Service
      33. public class ${moduleClass}Service {
      34. ​
      35.     @Autowired
      36.     private ${moduleClass}Dao ${moduleVar}Dao;
      37. ​
      38.     /**
      39.      * 根据id查询
      40.      */
      41.     public ${moduleClass}Entity getById(Long id){
      42.         return  ${moduleVar}Dao.selectById(id);
      43.     }
      44. ​
      45.     /**
      46.      * 分页查询
      47.      * @author ${author}
      48.      * @date ${date}
      49.      */
      50.     public ResponseDTO> queryByPage(${moduleClass}QueryDTO queryDTO) {
      51.         Page page = SmartPageUtil.convert2QueryPage(queryDTO);
      52.         IPage<${moduleClass}VO> voList = ${moduleVar}Dao.queryByPage(page, queryDTO);
      53.         PageResultDTO<${moduleClass}VO> pageResultDTO = SmartPageUtil.convert2PageResult(voList);
      54.         return ResponseDTO.succData(pageResultDTO);
      55.     }
      56. ​
      57.     /**
      58.      * 添加
      59.      * @author ${author}
      60.      * @date ${date}
      61.      */
      62.     public ResponseDTO add(${moduleClass}AddDTO addDTO) {
      63.         ${moduleClass}Entity entity = SmartBeanUtil.copy(addDTO, ${moduleClass}Entity.class);
      64.         ${moduleVar}Dao.insert(entity);
      65.         return ResponseDTO.succ();
      66.     }
      67. ​
      68.     /**
      69.      * 编辑
      70.      * @author ${author}
      71.      * @date ${date}
      72.      */
      73.     @Transactional(rollbackFor = Exception.class)
      74.     public ResponseDTO update(${moduleClass}UpdateDTO updateDTO) {
      75.         ${moduleClass}Entity entity = SmartBeanUtil.copy(updateDTO, ${moduleClass}Entity.class);
      76.         ${moduleVar}Dao.updateById(entity);
      77.         return ResponseDTO.succ();
      78.     }
      79. ​
      80.     /**
      81.      * 删除
      82.      * @author ${author}
      83.      * @date ${date}
      84.      */
      85.     @Transactional(rollbackFor = Exception.class)
      86.     public ResponseDTO deleteByIds(List idList) {
      87.         ${moduleVar}Dao.deleteByIdList(idList);
      88.         return ResponseDTO.succ();
      89.     }
      90. ​
      91.     /**
      92.      * 查询全部导出对象
      93.      * @author ${author}
      94.      * @date ${date}
      95.      */
      96.     public List<${moduleClass}ExcelVO> queryAllExportData(${moduleClass}QueryDTO queryDTO) {
      97.         return ${moduleVar}Dao.queryAllExportData( queryDTO);
      98.     }
      99. ​
      100.     /**
      101.      * 批量查询导出对象
      102.      * @author ${author}
      103.      * @date ${date}
      104.      */
      105.     public List<${moduleClass}ExcelVO> queryBatchExportData(List idList) {
      106.         return ${moduleVar}Dao.queryBatchExportData(idList);
      107.     }
      108. }

    • Mapper:

      1. "1.0" encoding="UTF-8"?>
      2. "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
      3. "${basePackage}.module.${modulePackage}.dao.${moduleClass}Dao">
      4. ​
      5.     "${moduleClass}VO" type="${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}VO">
      6.     "${moduleClass}ExcelVO" type="${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}ExcelVO">
      7. ​
      8. ​
      9.     
      10. ​
      11.     
      12. ​
      13.     
      14. ​
      15.     "deleteById">
      16.         delete from ${tableName} where id = #{id}
      17.     
      18. ​
      19.     "deleteByIdList">
      20.         delete from ${tableName} where id in
      21.         "idList" open="(" close=")" separator="," item="item">
      22.             #{item}
      23.         
      24.     
      25. ​

    • 查询表信息：

      1. <select id="selectTableDesc" resultType="String">
      2.     select
      3.         table_comment
      4.     from information_schema.tables
      5.     where table_schema = (select database()) and table_name = #{tableName}
      6. </select>
      7. ​
      8. <select id="selectTableColumn" resultMap="ColumnDTO">
      9.     select
      10.         column_name as columnName,
      11.         data_type as columnType,
      12.         column_comment as columnDesc
      13.     from information_schema.columns
      14.     where table_schema = (select database()) AND  table_name = #{tableName} order by ordinal_position
      15. </select>

    • 加载模板、组装数据

      1. public Map codeTemplates(String moduleClass, String basePackage, String modulePackage) {
      2.     String basePath = basePackage.replaceAll("\\.", File.separator );
      3.     String modulePath = modulePackage.replaceAll("\\.", File.separator );
      4.     String javaPackagePath = "java" + File.separator + basePath + File.separator + modulePath + File.separator;
      5.     String xmlPackagePath = "mapper" + File.separator + modulePath + File.separator;
      6.     String frontPackagePath = "web" + File.separator;
      7.     Map templateMap = new HashMap<>();
      8.     //后端
      9.     templateMap.put("templates/codegenerator/java/Controller.java.vm", javaPackagePath + "controller" + File.separator + moduleClass + "Controller.java" );
      10.     templateMap.put("templates/codegenerator/java/Dao.java.vm", javaPackagePath + "dao" + File.separator + moduleClass + "Dao.java" );
      11.     templateMap.put("templates/codegenerator/java/Dao.xml.vm", xmlPackagePath + moduleClass + "Mapper.xml" );
      12.     templateMap.put("templates/codegenerator/java/AddDTO.java.vm", javaPackagePath + "domain" + File.separator + "dto" + File.separator + moduleClass + "AddDTO.java" );
      13.     templateMap.put("templates/codegenerator/java/UpdateDTO.java.vm", javaPackagePath + "domain" + File.separator + "dto" + File.separator + moduleClass + "UpdateDTO.java" );
      14.     templateMap.put("templates/codegenerator/java/Entity.java.vm", javaPackagePath + "domain" + File.separator + "entity" + File.separator + moduleClass + "Entity.java" );
      15.     templateMap.put("templates/codegenerator/java/VO.java.vm", javaPackagePath + "domain" + File.separator + "vo" + File.separator + moduleClass + "VO.java" );
      16.     templateMap.put("templates/codegenerator/java/ExcelVO.java.vm", javaPackagePath + "domain" + File.separator + "vo" + File.separator + moduleClass + "ExcelVO.java" );
      17.     templateMap.put("templates/codegenerator/java/QueryDTO.java.vm", javaPackagePath + "domain" + File.separator + "dto" + File.separator + moduleClass + "QueryDTO.java" );
      18.     templateMap.put("templates/codegenerator/java/Service.java.vm", javaPackagePath + "service" + File.separator + moduleClass + "Service.java" );
      19.     //前端
      20.     String webPackageName = CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, moduleClass).replaceAll("_", "-" );
      21.     templateMap.put("templates/codegenerator/web/Api.js.vm", frontPackagePath + "api" + File.separator + webPackageName + ".js" );
      22.     templateMap.put("templates/codegenerator/web/Router.js.vm", frontPackagePath + "router" + File.separator + webPackageName + ".js" );
      23.     templateMap.put("templates/codegenerator/web/List.vue.vm", frontPackagePath + webPackageName + File.separator + webPackageName + "-list.vue" );
      24.     templateMap.put("templates/codegenerator/web/ListForm.vue.vm", frontPackagePath + webPackageName + File.separator + "components" + File.separator + webPackageName + "-list-form.vue" );
      25.     return templateMap;
      26. }

      1. Properties p = new Properties();
      2. p.put("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
      3. p.put("directive.foreach.counter.name", "velocityCount");
      4. p.put("directive.foreach.counter.initial.value", "1");
      5. Velocity.init(p);
      6. Map map = new HashMap<>();
      7. map.put("company", codeGenerator.getCompany());
      8. map.put("tableName", codeGenerator.getTableName());
      9. map.put("basePackage", basePackage);
      10. map.put("modulePackage", modulePackage);
      11. map.put("moduleClass", moduleClass);
      12. map.put("tableDesc", tableDesc);
      13. map.put("author", author);
      14. map.put("date", date);
      15. map.put("moduleVar", moduleVar);
      16. map.put("columnList", columnList);
      17. map.put("queryFieldList", queryFieldList);
      18. map.put("queryImports", queryImports);
      19. map.put("dtoImports", dtoImports);
      20. map.put("entityImports", entityImports);
      21. map.put("webModuleName", CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, moduleClass).replaceAll("_", "-"));
      22. map.put("upperCamel", CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_CAMEL, moduleClass));
      23. //前端的变量
      24. map.put("ViewUIMessage", "$Message");
      25. map.put("VueRefs", "$refs");

    • 创建Velocity上下文，生成代码

      1. VelocityContext context = new VelocityContext(map);
      2. ​
      3. private void codeGenerator(VelocityContext context, Map codeTemplates) throws Exception {
      4.     String projectPath = getOutputDir();
      5. ​
      6.     Velocity.setProperty("input.encoding", "UTF-8");
      7.     Velocity.setProperty("output.encoding", "UTF-8");
      8. ​
      9.     for (Entry entry : codeTemplates.entrySet()) {
      10.         String template = entry.getKey();
      11.         String filePath = projectPath + entry.getValue();
      12.         String fileName = filePath.substring(filePath.lastIndexOf(File.separator) + 1);
      13.         String fileDir = filePath.replace(fileName, "");
      14.         File directory = new File(fileDir);
      15.         if (!directory.exists()) {
      16.             directory.mkdirs();
      17.         }
      18.         FileWriter writer;
      19.         try {
      20.             writer = new FileWriter(filePath);
      21.             Template tpl = Velocity.getTemplate(template, "UTF-8");
      22.             tpl.merge(context, writer);
      23.             writer.flush();
      24.             writer.close();
      25.         } catch (Exception e) {
      26.             log.error("", e);
      27.         }
      28.     }
      29. ​
      30. }

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  • 原文地址：https://blog.csdn.net/Andrew_Chenwq/article/details/126879948