一个简单的基于Ajax的异步查询

                                                <div class="form-group">
                                                    <label class="control-label col-md-3">机号</label>
                                                    <div class="col-md-4">
                                                        <input class="form-control" id="mask_jh" type="text" name="faultMonitor.jh" onblur="checkJh()"/>
                                                        <div id="checkJh" style="float:left"></div>
                                                    </div>
                                                </div>

HTML的主要代码如上

        		function checkJh(){
        			var jh = document.getElementById("mask_jh").value;
        			var checkJh = document.getElementById("checkJh");
        			//alert(jh);
        			$.ajax({
        				url:"checkJhFaultMonitorAction",
        				async:true,
        				type:"POST",
        				data:{"jh":jh},
        				success:function(data){
        					//alert(data.jh);
        					if(data.jh!=0){checkJh.innerHTML="";}
        					else{
        						$("#checkJh").html("未在数据库中的机号");
        						$("#checkJh").css("color","red"); 
        					}
        				},
        				error:function(){
        					//alert("请求失败");
        				},
        				dataType:"json"
        			});
        		}

主要的js代码

	public String checkJh() throws IOException {
		HttpServletRequest request = ServletActionContext.getRequest();//获取request对象
		request.setCharacterEncoding("UTF-8");
		HttpServletResponse response = ServletActionContext.getResponse()//获取response对象
		response.setContentType("text/html;charset=UTF-8");
		jh = request.getParameter("jh");
		List<AircraftInfo> aircraftList= new ArrayList<AircraftInfo>();
		AircraftInfo acInfo = aircraftInfoService.findById(jh);
		if(acInfo!=null)
		aircraftList.add(acInfo);
		int size = aircraftList.size();
		if(aircraftList.size()>0){
			response.getWriter().write("{\"jh\":"+size+"}");
		}
		else{response.getWriter().write("{\"jh\":"+0+"}");}
		return NONE;
	}

Action中的主要代码