code: protected void processGeneratedValue(EntityTable entityTable, EntityColumn entityColumn, GeneratedValue generatedValue) {
          if ("JDBC".equals(generatedValue.generator())) {
              entityColumn.setIdentity(true);
              entityColumn.setGenerator("JDBC");
              entityTable.setKeyProperties(entityColumn.getProperty());
              entityTable.setKeyColumns(entityColumn.getColumn());
          } else {
              //允许通过generator来设置获取id的sql,例如mysql=CALL IDENTITY(),hsqldb=SELECT SCOPE_IDENTITY()
              //允许通过拦截器参数设置公共的generator
              if (generatedValue.strategy() == GenerationType.IDENTITY) {
                  //mysql的自动增长
                  entityColumn.setIdentity(true);
                  if (!"".equals(generatedValue.generator())) {
                      String generator = null;
                      IdentityDialect identityDialect = IdentityDialect.getDatabaseDialect(generatedValue.generator());
                      if (identityDialect != null) {
                          generator = identityDialect.getIdentityRetrievalStatement();
                      } else {
                          generator = generatedValue.generator();
                      }
                      entityColumn.setGenerator(generator);
                  }
              } else {
                  throw new MapperException(entityColumn.getProperty()
                          + " - 该字段@GeneratedValue配置只允许以下几种形式:" +
                          "\n1.useGeneratedKeys的@GeneratedValue(generator=\\\"JDBC\\\")  " +
                          "\n2.类似mysql数据库的@GeneratedValue(strategy=GenerationType.IDENTITY[,generator=\"Mysql\"])");
              }
          }
      }
docs: 处理 GeneratedValue 注解
  
  @param entityTable
  @param entityColumn
  @param generatedValue