示例项目地址: https://git.code.tencent.com/xinzhang0618/code-generator.git

实现思路

  1. 使用velocity, 先制作模板, 然后填充数据, 生成文件即可
  2. 表结构信息在information_schema.TABLES, information_schema.COLUMNS两个表中, 查询到表结构信息后, 构建成模板所需的数据即可
  3. 要注意解决一些特殊场景, 比如枚举的处理, 实体添加自定义字段, 布尔类型的is方法, 有无模块定义(有模块目录结构会不同)等
  4. 难点在于如何灵活的将配置分离

解析

CodeGenerator

  1. package top.xinzhang0618.code.generator;
  3. import com.alibaba.fastjson.JSON;
  4. import org.apache.velocity.Template;
  5. import org.apache.velocity.VelocityContext;
  6. import org.apache.velocity.app.Velocity;
  7. import org.springframework.beans.factory.annotation.Autowired;
  8. import org.springframework.beans.factory.annotation.Value;
  9. import org.springframework.stereotype.Component;
  10. import org.springframework.util.CollectionUtils;
  11. import top.xinzhang0618.code.generator.config.Configuration;
  12. import top.xinzhang0618.code.generator.config.Profile;
  13. import top.xinzhang0618.code.generator.schema.domain.Bean;
  14. import top.xinzhang0618.code.generator.schema.domain.Field;
  15. import top.xinzhang0618.code.generator.service.SchemaService;
  16. import top.xinzhang0618.code.generator.util.FileUtils;
  17. import top.xinzhang0618.code.generator.util.StringUtils;
  19. import java.io.StringWriter;
  20. import java.time.LocalDate;
  21. import java.util.*;
  23. /**
  24.  * @author xinzhang
  25.  * @date 2020/11/6 9:59
  26.  */
  27. @Component
  28. public class CodeGenerator {
  29.     @Autowired
  30.     private SchemaService schemaService;
  31.     @Value("${spring.profiles.active}")
  32.     private String activeProfile;
  34.     public void run() {
  35.         Configuration configuration = JSON.parseObject(FileUtils.read("json/configuration.json"), Configuration.class);
  36.         Profile profile = JSON.parseObject(FileUtils.read("json/" + activeProfile + ".json"), Profile.class);
  38.         // 初始化流程引擎
  39.         Properties prop = new Properties();
  40.         prop.put("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
  41.         Velocity.init(prop);
  43.         //封装模板数据
  44.         Map<String, Object> context = new HashMap<>(6);
  45.         context.put("basePackage", profile.getBasePackage());
  46.         context.put("date", LocalDate.now());
  48.         Map<String, List<String>> moduleMap = profile.getModuleMap();
  49.         String outPutDir =
  50.                 System.getProperty("user.dir") + "/target/" + profile.getBasePackage().replace(".", "/") + "/";
  51.         moduleMap.forEach((module, tables) -> {
  52.             List<Bean> beans = schemaService.listBeans(profile.getDataSources(), tables);
  53.             context.put("module", module);
  54.             beans.forEach(bean -> {
  55.                 processBean(configuration, profile, bean);
  56.                 addExtendImport(bean, context);
  57.                 context.put("bean", bean);
  58.                 configuration.getTemplates().forEach(template -> {
  59.                     StringWriter sw = new StringWriter();
  60.                     Template tpl = Velocity.getTemplate(template, "UTF-8");
  61.                     String fileName = buildFileName(outPutDir, module, template, bean.getBeanName());
  62.                     tpl.merge(new VelocityContext(context), sw);
  63.                     FileUtils.writeFile(fileName, sw.toString());
  64.                 });
  65.             });
  67.         });
  68.     }
  70.     private void addExtendImport(Bean bean, Map<String, Object> context) {
  71.         if (!CollectionUtils.isEmpty(bean.getExtendFields())) {
  72.             List<String> extendImports = new ArrayList<>();
  73.             boolean needImportList = bean.getExtendFields().stream().anyMatch(field -> field.getJavaType().startsWith(
  74.                     "List"));
  75.             if (needImportList) {
  76.                 extendImports.add("java.util.List");
  77.             }
  78.             context.put("extendImports", extendImports);
  79.         }
  80.     }
  82.     private String buildFileName(String outPutDir, String module, String template, String beanName) {
  83.         if (template.contains("domain")) {
  84.             return outPutDir + "domain/" + module + "/" + beanName + ".java";
  85.         } else if (template.contains("mapper.java")) {
  86.             return outPutDir + "mapper/" + module + "/" + beanName + "Mapper.java";
  87.         } else if (template.contains("mapper.xml")) {
  88.             return outPutDir + "mapper/xml/" + module + "/" + beanName + "Mapper.xml";
  89.         } else if (template.contains("service.java")) {
  90.             return outPutDir + "service/" + module + "/" + beanName + "Service.java";
  91.         } else {
  92.             return outPutDir + "service/impl/" + module + "/" + beanName + "ServiceImpl.java";
  93.         }
  94.     }
  96.     public void processBean(Configuration configuration, Profile profile, Bean bean) {
  97.         bean.setBeanName(parseBeanName(bean.getTableName(), profile.getTablePrefix()));
  98.         bean.getFields().forEach(field -> {
  99.             field.setFieldName(parseFieldName(field.getColumnName()));
  100.             field.setJavaType(configuration.getTypeMap().getOrDefault(field.getJdbcType(), "String"));
  101.             if (field.getColumnName().startsWith("is")) {
  102.                 field.setGetName("is" + StringUtils.upperFirst(field.getFieldName()));
  103.             } else {
  104.                 field.setGetName("get" + StringUtils.upperFirst(field.getFieldName()));
  105.             }
  106.             field.setSetName("set" + StringUtils.upperFirst(field.getFieldName()));
  107.         });
  109.         if (!CollectionUtils.isEmpty(profile.getExtendMap()) && profile.getExtendMap().get(bean.getTableName()) != null) {
  110.             Profile.ExtendInfo extendInfo = profile.getExtendMap().get(bean.getTableName());
  111.             // 替换枚举类型
  112.             if (!CollectionUtils.isEmpty(extendInfo.getEnumMap())) {
  113.                 Map<String, String> enumMap = extendInfo.getEnumMap();
  114.                 bean.getFields().forEach(field -> field.setJavaType(enumMap.get(field.getColumnName()) == null ?
  115.                         field.getJavaType() : enumMap.get(field.getColumnName())));
  116.                 bean.setEnumJavaTypes(enumMap.values());
  117.             }
  119.             // 添加字段
  120.             bean.setExtendFields(extendInfo.getExtendFields());
  121.         }
  122.     }
  124.     private String parseBeanName(String tableName, String tablePrefix) {
  125.         String[] words = tableName.replace(tablePrefix, "").split("_");
  126.         StringBuilder sb = new StringBuilder();
  127.         Arrays.stream(words).forEach(w -> sb.append(StringUtils.upperFirst(w)));
  128.         return sb.toString();
  129.     }
  131.     private static String parseFieldName(String columnName) {
  132.         String[] words = columnName.split("_");
  133.         ArrayList<String> list = new ArrayList<>(Arrays.asList(words));
  134.         list.remove("is");
  135.         StringBuilder sb = new StringBuilder(list.get(0));
  136.         for (int i = 1; i < list.size(); i++) {
  137.             sb.append(StringUtils.upperFirst(list.get(i)));
  138.         }
  139.         return sb.toString();
  140.     }
  141. }

代码如上, 核心的步骤:

  • 初始化流程引擎, 获取全局配置等
  • 封装模板数据
    • 包目录, 作者信息
    • 模块
      • 表—>实体
        • 构建实体名
        • 构建字段名称, getter/setter
        • 枚举处理
        • 添加额外字段
        • 添加额外导入
  • 从全局配置中拿到模板, 构建生成路径, 并生成文件

查询sql:

  1.  <!-- 通用查询映射结果 -->
  2.     <resultMap id="beanResultMap" type="top.xinzhang0618.code.generator.schema.domain.Bean">
  3.         <result column="table_name" property="tableName"/>
  4.         <result column="table_comment" property="comment"/>
  5.         <collection property="fields" ofType="top.xinzhang0618.code.generator.schema.domain.Field">
  6.             <result column="column_name" property="columnName"/>
  7.             <result column="data_type" property="jdbcType"/>
  8.             <result column="column_comment" property="comment"/>
  9.             <result column="pk" property="pk"/>
  10.         </collection>
  11.     </resultMap>
  13.     <select id="listBeans" resultMap="beanResultMap">
  14.     SELECT
  15.         t.table_name,
  16.         t.table_comment,
  17.         c.column_name,
  18.         c.data_type,
  19.         c.column_comment,
  20.     IF
  21.     ( c.column_key = 'PRI', TRUE, FALSE ) as pk
  22.     FROM
  23.         information_schema.TABLES t
  24.         LEFT JOIN information_schema.COLUMNS c ON t.table_name = c.table_name
  25.     WHERE
  26.         t.table_schema in
  27.         <foreach item="item" index="index" collection="databases" open="(" separator="," close=")">
  28.             #{item}
  29.         </foreach>
  30.         and t.table_name in
  31.         <foreach item="item" index="index" collection="tableNames" open="(" separator="," close=")">
  32.             #{item}
  33.         </foreach>
  34.     ORDER BY
  35.         c.ordinal_position
  36.     </select>

配置分离

为了方便配置的编写, 此处使用了json作为补充的配置文件(项目使用springboot, 其yml文件仅有数据库连接信息)
1.通用配置比如模板位置以及字段数据库类型到java数据类型的对应关系放到全局配置文件configuration.json中

  1. {
  2.   "templates": [
  3.     "templates/domain.java.vm",
  4.     "templates/mapper.java.vm",
  5.     "templates/mapper.xml.vm",
  6.     "templates/service.java.vm",
  7.     "templates/serviceImpl.java.vm"
  8.   ],
  9.   "typeMap": {
  10.     "unique identifier": "String",
  11.     "bit": "Boolean",
  12.     "date": "LocalDate",
  13.     "timestamp": "LocalDateTime",
  14.     "datetime": "LocalDateTime",
  15.     "varchar": "String",
  16.     "nvarchar": "String",
  17.     "mediumtext": "String",
  18.     "char": "String",
  19.     "bigint": "Long",
  20.     "bigint unsigned": "Long",
  21.     "int": "Integer",
  22.     "int unsigned": "Integer",
  23.     "double": "Double",
  24.     "double unsigned": "Double",
  25.     "decimal": "Double",
  26.     "decimal unsigned": "Double",
  27.     "tinyint": "Boolean",
  28.     "tinyint unsigned": "Integer",
  29.     "time": "LocalTime",
  30.     "smallint": "Integer",
  31.     "smallint unsigned": "Integer"
  32.   }
  33. }

2.针对每个项目的配置单独建立该项目的配置文件, 如下demo.json

  1. {
  2.   "basePackage": "top.xinzhang0618.oa",
  3.   "dataSources": [
  4.     "oa_admin_dev",
  5.     "oa_biz_dev"
  6.   ],
  7.   "tablePrefix": "oa_",
  8.   "moduleMap": {
  9.     "base": [
  10.       "oa_company",
  11.       "oa_data_dict",
  12.       "oa_department",
  13.       "oa_menu",
  14.       "oa_message",
  15.       "oa_privilege",
  16.       "oa_role",
  17.       "oa_user",
  18.       "oa_user_role"
  19.     ],
  20.     "test": [
  21.       "oa_user"
  22.     ]
  23.   },
  24.   "extendMap": {
  25.     "oa_data_dict": {
  26.       "enumMap": {
  27.         "data_dict_type": "DataDictType"
  28.       },
  29.       "extendFields": [
  30.         {
  31.           "fieldName": "testField",
  32.           "javaType": "String",
  33.           "comment": "测试添加额外字段",
  34.           "setName": "setTestField",
  35.           "getName": "getTestField"
  36.         }
  37.       ]
  38.     }
  39.   }
  40. }