JPA：动态传入表名对表进行修改，我这里主要演示oracle空表无法导出的情况

 @Query(value = "select ‘alter table ‘ || a.table_name || ‘ allocate extent‘ from user_tables a where a.table_name not in (select segment_name from user_segments where segment_type = ‘TABLE‘)", nativeQuery = true)
 List<String> findTables();

　List<String> list = versionDao.findTables();
    if (!list.isEmpty() && list != null) {
        for (String str : list) {
　　　　　　//Str ： alter table RECORD allocate extent，截取RECORD
          String reg = "alter table (.*?) allocate extent";
          Pattern compile = Pattern.compile(reg);
          Matcher matcher = compile.matcher(str);
          while (matcher.find()) {
            String sql = "alter table " + matcher.group(1) + " allocate extent";
            Query query = entityManager.createNativeQuery(sql);
            query.executeUpdate();
          }
       }
    }