AJAX 同步請求的JS

<script type="text/javascript">
			function cbxxsubmit(){
					var fileItem = $('.fileitem > a');
					if(fileItem.length > 0){
						var uploadHisType = document.getElementById("uploadHisType").value;
						if(uploadHisType==0){
							var checkboolean = true;
							var year = $("#dataYear").find("option:selected").text();
							var month = $("#dataMonth").find("option:selected").text();
							 $.ajax({
								    type:"POST",
								    async:false,
								    url:"validhave.action",
								    data:{year: year, month: month},
								    success:function(msg){
									    if(msg=="no"){   
									    	alert_modal("該年月已上傳數據不允許重複上傳！", "");
											checkboolean = false;
									    }
								    }
							});
							if(!checkboolean){
								return;
							}
						}
						 confirm_modal('#save', '', true);
					}else{
						alert_modal("請上傳保費結構及賠付率情況統計表！", "");
					}
			}
		</script>

action代碼：

public String validhave(){
		PrintWriter pw = null;
		try {
			pw = response.getWriter();
		} catch (IOException e1) {
			e1.printStackTrace();
		}
		String year = request.getParameter("year");
		String month = request.getParameter("month");
		Calendar now = Calendar.getInstance();  
		CxywfxCheckFormQuery query = cxywfxCheckFormService.createQuery();
		query.tableType(TABLE_TYPE);
		query.createUsername(loginedUser().getUser().getUsername());
		if(year!=null&&!"".equals(year)&&month!=null&&!"".equals(month)){
			query.dataYear(year);
			query.dataMonth(month);
		}else{
			if(now.get(Calendar.MONTH)+1!=1){
				query.dataYear(String.valueOf(now.get(Calendar.YEAR)));
				query.dataMonth(String.valueOf(now.get(Calendar.MONTH)));
			}else{
				query.dataYear(String.valueOf(now.get(Calendar.YEAR)-1));
				query.dataMonth("12");
			}
		}
		Integer [] statu = {0,1};
		query.checkNumbers(statu);
		List<CxywfxCheckForm> cxyw = query.list();
		if(cxyw.size()>0){//判斷該時間段是否已存在
			pw.write("no");
			return null;
		}
		return null;
	}