目录原理实战
原理
其原理如图：
1.配置数据源信息（包括表名）
2.读取数据表字段信息：列名、类型、字段注释、表注释
3.编写代码模板，并将该模板加载到内存
4.根据模板所需，组装Velocity引擎渲染所需字段Map
5.创建Velocity上下文，将代码模板和替换字段传入
6.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
1.通过maven构建项目，引入依赖：
<dependency> <artifactId>velocity</artifactId> <groupId>org.apache.velocity</groupId> <exclusions> <exclusion> <artifactId>commons-collections</artifactId> <groupId>commons-collections</groupId> </exclusion> </exclusions></dependency><dependency> <groupId>org.apache.velocity</groupId> <artifactId>velocity-engine-core</artifactId></dependency>
2.在resources/templates/codegenerator目录下面编写代码模板：
VO:
package ${basePackage}.module.${modulePackage}.domain.vo;import lombok.Data;#foreach ($dtoImport in $dtoImports)$dtoImport#endimport com.fasterxml.jackson.annotation.JsonFormat;import io.swagger.annotations.ApiModelProperty;/** * [ ${tableDesc} ] * * @author ${author} * @version 1.0 * @company ${company} * @copyright (c) ${company}Inc. All rights reserved. * @date ${date} * @since JDK1.8 */@Datapublic class ${moduleClass}VO {#foreach ($column in $columnList)#if($column.fieldType == 'Date') @ApiModelProperty("${column.columnDesc}") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") private $column.fieldType $column.fieldName;#else @ApiModelProperty("${column.columnDesc}") private $column.fieldType $column.fieldName;#end#end}
SERVICE:
package ${basePackage}.module.${modulePackage}.service;import com.baomidou.mybatisplus.core.metadata.IPage;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import ${basePackage}.common.domain.PageResultDTO;import ${basePackage}.common.domain.ResponseDTO;import ${basePackage}.module.${modulePackage}.dao.${moduleClass}Dao;import ${basePackage}.module.${modulePackage}.domain.dto.${moduleClass}AddDTO;import ${basePackage}.module.${modulePackage}.domain.dto.${moduleClass}UpdateDTO;import ${basePackage}.module.${modulePackage}.domain.dto.${moduleClass}QueryDTO;import ${basePackage}.module.${modulePackage}.domain.entity.${moduleClass}Entity;import ${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}VO;import ${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}ExcelVO;import ${basePackage}.util.SmartPageUtil;import ${basePackage}.util.SmartBeanUtil;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.transaction.annotation.Transactional;import java.util.List;/** * [ ${tableDesc} ] * * @author ${author} * @version 1.0 * @company ${company} * @copyright (c) ${company}Inc. All rights reserved. * @date ${date} * @since JDK1.8 */@Servicepublic class ${moduleClass}Service { @Autowired private ${moduleClass}Dao ${moduleVar}Dao; /** * 根据id查询 */ public ${moduleClass}Entity getById(Long id){ return ${moduleVar}Dao.selectById(id); } /** * 分页查询 * @author ${author} * @date ${date} */ public ResponseDTO<PageResultDTO<${moduleClass}VO>> queryByPage(${moduleClass}QueryDTO queryDTO) { Page page = SmartPageUtil.convert2QueryPage(queryDTO); IPage<${moduleClass}VO> voList = ${moduleVar}Dao.queryByPage(page, queryDTO); PageResultDTO<${moduleClass}VO> pageResultDTO = SmartPageUtil.convert2PageResult(voList); return ResponseDTO.succData(pageResultDTO); } /** * 添加 * @author ${author} * @date ${date} */ public ResponseDTO<String> add(${moduleClass}AddDTO addDTO) { ${moduleClass}Entity entity = SmartBeanUtil.copy(addDTO, ${moduleClass}Entity.class); ${moduleVar}Dao.insert(entity); return ResponseDTO.succ(); } /** * 编辑 * @author ${author} * @date ${date} */ @Transactional(rollbackFor = Exception.class) public ResponseDTO<String> update(${moduleClass}UpdateDTO updateDTO) { ${moduleClass}Entity entity = SmartBeanUtil.copy(updateDTO, ${moduleClass}Entity.class); ${moduleVar}Dao.updateById(entity); return ResponseDTO.succ(); } /** * 删除 * @author ${author} * @date ${date} */ @Transactional(rollbackFor = Exception.class) public ResponseDTO<String> deleteByIds(List<Long> idList) { ${moduleVar}Dao.deleteByIdList(idList); return ResponseDTO.succ(); } /** * 查询全部导出对象 * @author ${author} * @date ${date} */ public List<${moduleClass}ExcelVO> queryAllExportData(${moduleClass}QueryDTO queryDTO) { return ${moduleVar}Dao.queryAllExportData( queryDTO); } /** * 批量查询导出对象 * @author ${author} * @date ${date} */ public List<${moduleClass}ExcelVO> queryBatchExportData(List<Long> idList) { return ${moduleVar}Dao.queryBatchExportData(idList); }}
Mapper:
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="${basePackage}.module.${modulePackage}.dao.${moduleClass}Dao"> <resultMap id="${moduleClass}VO" type="${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}VO"></resultMap> <resultMap id="${moduleClass}ExcelVO" type="${basePackage}.module.${modulePackage}.domain.vo.${moduleClass}ExcelVO"></resultMap> <select id="queryByPage" resultMap="${moduleClass}VO"> select#foreach($column in $columnList)#if($velocityCount != $columnList.size()) $column.columnName,#else $column.columnName#end#end from ${tableName} <where>#foreach($queryField in $queryFieldList)#if ($queryField.sqlOperate == 'like') <if test="queryDTO.${queryField.fieldName} != null and queryDTO.${queryField.fieldName} != ''"> AND INSTR($queryField.columnName,#{queryDTO.$queryField.fieldName}) </if>#end#if ($queryField.sqlOperate == 'equals')#if ($queryField.fieldType == 'String') <if test="queryDTO.${queryField.fieldName} != null and queryDTO.${queryField.fieldName} != ''"> AND $queryField.columnName = #{queryDTO.$queryField.fieldName} </if>#else <if test="queryDTO.${queryField.fieldName} != null"> AND $queryField.columnName = #{queryDTO.$queryField.fieldName} </if>#end#end#if ($queryField.sqlOperate == 'in') <if test="queryDTO.${queryField.fieldName}List !=null and queryDTO.${queryField.fieldName}List.size() > 0"> and $queryField.columnName in <foreach collection="queryDTO.${queryField.fieldName}List" open="(" index="index" separator="," close=")" item="item"> #{item} </foreach> </if>#end#end <if test="queryDTO.createTimeBegin != null "> AND create_time >= #{queryDTO.createTimeBegin} </if> <if test="queryDTO.createTimeEnd != null "> AND create_time <= #{queryDTO.createTimeEnd} </if> <if test="queryDTO.updateTimeBegin != null "> AND update_time >= #{queryDTO.updateTimeBegin} </if> <if test="queryDTO.updateTimeEnd != null "> AND update_time <= #{queryDTO.updateTimeEnd} </if> </where> </select> <select id="queryAllExportData" resultMap="${moduleClass}ExcelVO"> select#foreach($column in $columnList)#if($velocityCount != $columnList.size()) $column.columnName,#else $column.columnName#end#end from ${tableName} <where>#foreach($queryField in $queryFieldList)#if ($queryField.sqlOperate == 'like') <if test="queryDTO.${queryField.fieldName} != null and queryDTO.${queryField.fieldName} != ''"> AND INSTR($queryField.columnName,#{queryDTO.$queryField.fieldName}) </if>#end#if ($queryField.sqlOperate == 'equals')#if ($queryField.fieldType == 'String') <if test="queryDTO.${queryField.fieldName} != null and queryDTO.${queryField.fieldName} != ''"> AND $queryField.columnName = #{queryDTO.$queryField.fieldName} </if>#else <if test="queryDTO.${queryField.fieldName} != null"> AND $queryField.columnName = #{queryDTO.$queryField.fieldName} </if>#end#end#if ($queryField.sqlOperate == 'in') <if test="queryDTO.${queryField.fieldName}List !=null and queryDTO.${queryField.fieldName}List.size() > 0"> and $queryField.columnName in <foreach collection="queryDTO.${queryField.fieldName}List" open="(" index="index" separator="," close=")" item="item"> #{item} </foreach> </if>#end#end <if test="queryDTO.createTimeBegin != null "> AND create_time >= #{queryDTO.createTimeBegin} </if> <if test="queryDTO.createTimeEnd != null "> AND create_time <= #{queryDTO.createTimeEnd} </if> <if test="queryDTO.updateTimeBegin != null "> AND update_time >= #{queryDTO.updateTimeBegin} </if> <if test="queryDTO.updateTimeEnd != null "> AND update_time <= #{queryDTO.updateTimeEnd} </if> </where> </select> <select id="queryBatchExportData" resultMap="${moduleClass}ExcelVO"> select#foreach($column in $columnList)#if($velocityCount != $columnList.size()) $column.columnName,#else $column.columnName#end#end from ${tableName} where id in <foreach collection="idList" open="(" close=")" separator="," item="item"> #{item} </foreach> </select> <delete id="deleteById"> delete from ${tableName} where id = #{id} </delete> <delete id="deleteByIdList"> delete from ${tableName} where id in <foreach collection="idList" open="(" close=")" separator="," item="item"> #{item} </foreach> </delete></mapper>
3.查询表信息：
<select id="selectTableDesc" resultType="String"> select table_comment from information_schema.tables where table_schema = (select database()) and table_name = #{tableName}</select><select id="selectTableColumn" resultMap="ColumnDTO"> select column_name as columnName, data_type as columnType, column_comment as columnDesc from information_schema.columns where table_schema = (select database()) AND table_name = #{tableName} order by ordinal_position</select>
4.加载模板、组装数据
public Map<String, String> codeTemplates(String moduleClass, String basePackage, String modulePackage) { String basePath = basePackage.replaceAll("\\.", File.separator ); String modulePath = modulePackage.replaceAll("\\.", File.separator ); String javaPackagePath = "java" + File.separator + basePath + File.separator + modulePath + File.separator; String xmlPackagePath = "mapper" + File.separator + modulePath + File.separator; String frontPackagePath = "web" + File.separator; Map<String, String> templateMap = new HashMap<>(); //后端 templateMap.put("templates/codegenerator/java/Controller.java.vm", javaPackagePath + "controller" + File.separator + moduleClass + "Controller.java" ); templateMap.put("templates/codegenerator/java/Dao.java.vm", javaPackagePath + "dao" + File.separator + moduleClass + "Dao.java" ); templateMap.put("templates/codegenerator/java/Dao.xml.vm", xmlPackagePath + moduleClass + "Mapper.xml" ); templateMap.put("templates/codegenerator/java/AddDTO.java.vm", javaPackagePath + "domain" + File.separator + "dto" + File.separator + moduleClass + "AddDTO.java" ); templateMap.put("templates/codegenerator/java/UpdateDTO.java.vm", javaPackagePath + "domain" + File.separator + "dto" + File.separator + moduleClass + "UpdateDTO.java" ); templateMap.put("templates/codegenerator/java/Entity.java.vm", javaPackagePath + "domain" + File.separator + "entity" + File.separator + moduleClass + "Entity.java" ); templateMap.put("templates/codegenerator/java/VO.java.vm", javaPackagePath + "domain" + File.separator + "vo" + File.separator + moduleClass + "VO.java" ); templateMap.put("templates/codegenerator/java/ExcelVO.java.vm", javaPackagePath + "domain" + File.separator + "vo" + File.separator + moduleClass + "ExcelVO.java" ); templateMap.put("templates/codegenerator/java/QueryDTO.java.vm", javaPackagePath + "domain" + File.separator + "dto" + File.separator + moduleClass + "QueryDTO.java" ); templateMap.put("templates/codegenerator/java/Service.java.vm", javaPackagePath + "service" + File.separator + moduleClass + "Service.java" ); //前端 String webPackageName = CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, moduleClass).replaceAll("_", "-" ); templateMap.put("templates/codegenerator/web/Api.js.vm", frontPackagePath + "api" + File.separator + webPackageName + ".js" ); templateMap.put("templates/codegenerator/web/Router.js.vm", frontPackagePath + "router" + File.separator + webPackageName + ".js" ); templateMap.put("templates/codegenerator/web/List.vue.vm", frontPackagePath + webPackageName + File.separator + webPackageName + "-list.vue" ); templateMap.put("templates/codegenerator/web/ListForm.vue.vm", frontPackagePath + webPackageName + File.separator + "components" + File.separator + webPackageName + "-list-form.vue" ); return templateMap;}
Properties p = new Properties();p.put("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");p.put("directive.foreach.counter.name", "velocityCount");p.put("directive.foreach.counter.initial.value", "1");Velocity.init(p);Map<String, Object> map = new HashMap<>();map.put("company", codeGenerator.getCompany());map.put("tableName", codeGenerator.getTableName());map.put("basePackage", basePackage);map.put("modulePackage", modulePackage);map.put("moduleClass", moduleClass);map.put("tableDesc", tableDesc);map.put("author", author);map.put("date", date);map.put("moduleVar", moduleVar);map.put("columnList", columnList);map.put("queryFieldList", queryFieldList);map.put("queryImports", queryImports);map.put("dtoImports", dtoImports);map.put("entityImports", entityImports);map.put("webModuleName", CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, moduleClass).replaceAll("_", "-"));map.put("upperCamel", CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_CAMEL, moduleClass));//前端的变量map.put("ViewUIMessage", "$Message");map.put("VueRefs", "$refs");
5.创建Velocity上下文，生成代码
VelocityContext context = new VelocityContext(map);private void codeGenerator(VelocityContext context, Map<String, String> codeTemplates) throws Exception { String projectPath = getOutputDir(); Velocity.setProperty("input.encoding", "UTF-8"); Velocity.setProperty("output.encoding", "UTF-8"); for (Entry<String, String> entry : codeTemplates.entrySet()) { String template = entry.getKey(); String filePath = projectPath + entry.getValue(); String fileName = filePath.substring(filePath.lastIndexOf(File.separator) + 1); String fileDir = filePath.replace(fileName, ""); File directory = new File(fileDir); if (!directory.exists()) { directory.mkdirs(); } FileWriter writer; try { writer = new FileWriter(filePath); Template tpl = Velocity.getTemplate(template, "UTF-8"); tpl.merge(context, writer); writer.flush(); writer.close(); } catch (Exception e) { log.error("", e); } }}
以上就是如何使用Velocity引擎生成代码的详细内容，更多关于使用Velocity引擎生成代码的资料请关注其它相关文章！
人生最好的旅行，就是你在一个陌生的地方，
