关于异步校验

JSP:

$(document).ready(function(){
			$("#protocolName").change(function(){
				$.ajax({
					type: "post",
					async: false,
					cache: false,
					url: "<%=request.getContextPath()%>/clp/validateAction!getJzwmc.action",
					data:{"myaction":"getJzwmc","name":$(this).val()},
					success:function(exist){
						var existFlag=$(exist).find("response > exist_flag").text();
						if(existFlag!="false"){
							alert("此名称已被使用，请重新填写拟定名称！");
							$("#protocolName").val("");
						}else{
						
						}						
					},
					error:function(){
						alert("校验拟定名称失败");
					}
				}); 
			});
		});

java:

public void getJzwmc(){
		String rtn;
		request= ServletActionContext.getRequest(); 
		String name=this.request.getParameter("name");
		HttpServletResponse reponse=ServletActionContext.getResponse();
		//reponse.setContentType("application/json;charset=UTF-8");
		reponse.setContentType("text/xml;charset=utf-8");
		//JSONArray array = new JSONArray();
		 
		rtn=this.validateService.getJzwmc(name); 
		try {
			if(rtn!=null&&!"".equals(rtn)){
				reponse.setStatus(200);
				reponse.getWriter().println("<response>");
				reponse.getWriter().println("<exist_flag><![CDATA[true]]></exist_flag>");
				reponse.getWriter().println("</response>");
				reponse.getWriter().flush();
				reponse.getWriter().close();
			}else{
				reponse.setStatus(200);
				reponse.getWriter().println("<response>");
				reponse.getWriter().println("<exist_flag><![CDATA[false]]></exist_flag>");
				reponse.getWriter().println("</response>");
				reponse.getWriter().flush();
				reponse.getWriter().close();
			}
			
		} catch (IOException e) {
			e.printStackTrace();
		}
//		return null;
	}

记得当初没有将reponse.setStatus(200);的话jsp是接收不了参数的。还不是很明白为什么。。