操作clob类型

   Clob clob = null;
  String content=null; //帖子内容
  clob = rs.getClob(4);
  if(clob == null){   //clob为空时 内容为空             	
   content = null;	                	  
    }else{	                	
   long len = clob.length();
  //获得内容  
  content = clob.getSubString(1, (int) len);	         
 }