拼接字符串，逗号分隔技巧

  StringBuffer buffer = new StringBuffer();
  if(invoiceLst.size()>0){
   buffer.append(invoiceLst.get(0).getInvoiceId());
   for(int i=1;i<invoiceLst.size();i++){
    buffer.append(",").append(invoiceLst.get(i).getInvoiceId());
   }
  }