docs: protected void processKeySql(EntityTable entityTable, EntityColumn entityColumn, KeySql keySql) {
          if (keySql.useGeneratedKeys()) {
              entityColumn.setIdentity(true);
              entityColumn.setGenerator("JDBC");
              entityTable.setKeyProperties(entityColumn.getProperty());
              entityTable.setKeyColumns(entityColumn.getColumn());
          } else if (keySql.dialect() == IdentityDialect.DEFAULT) {
              entityColumn.setIdentity(true);
              entityColumn.setOrder(ORDER.AFTER);
          }  else if (keySql.dialect() != IdentityDialect.NULL) {
              //自动增长
              entityColumn.setIdentity(true);
              entityColumn.setOrder(ORDER.AFTER);
              entityColumn.setGenerator(keySql.dialect().getIdentityRetrievalStatement());
          } else if (StringUtil.isNotEmpty(keySql.sql())){
  
              entityColumn.setIdentity(true);
              entityColumn.setOrder(keySql.order());
              entityColumn.setGenerator(keySql.sql());
          } else if (keySql.genSql() != GenSql.NULL.class){
              entityColumn.setIdentity(true);
              entityColumn.setOrder(keySql.order());
              try {
                  GenSql genSql = keySql.genSql().newInstance();
                  entityColumn.setGenerator(genSql.genSql(entityTable, entityColumn));
              } catch (Exception e) {
                  log.error("实例化 GenSql 失败: " + e, e);
                  throw new MapperException("实例化 GenSql 失败: " + e, e);
              }
          } else if(keySql.genId() != GenId.NULL.class){
              entityColumn.setIdentity(false);
              entityColumn.setGenIdClass(keySql.genId());
          } else {
              throw new MapperException(entityTable.getEntityClass().getCanonicalName()
                      + " 类中的 @KeySql 注解配置无效!");
          }
      }