js取服务器端时间，并提供动态上载链接

最近项目中有这样一个需求：

页面动态刷新获取数据库中符合条件的数据的下载链接状态：如果已有可下载链接，就显示链接供用户下载，并显示服务器端当前时间；没有就继续动态获取。

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实现功能：

js取服务器端时间，并动态检索下载链接，显示到页面供用户下载。

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<script language="javascript">
var xmlhttp = null;
var interval = null;
var timeTimeout = null;
var statusValue = "";
var rtnData = new Array();
var btype;
var divContent = "";


/**
* 时间对象的格式化;
*/
Date.prototype.format = function(format){
 /*
  * eg:format="yyyy-MM-dd hh:mm:ss";
  */
 var o = {
  "M+" :  this.getMonth()+1,  //month
  "d+" :  this.getDate(),     //day
  "h+" :  this.getHours(),    //hour
  "m+" :  this.getMinutes(),  //minute
  "s+" :  this.getSeconds(), //second
  "q+" :  Math.floor((this.getMonth()+3)/3),  //quarter
  "S"  :  this.getMilliseconds() //millisecond
 }
  
 if(/(y+)/.test(format)) {
 	format = format.replace(RegExp.$1, (this.getFullYear()+"").substr(4 - RegExp.$1.length));
 }
 
   for(var k in o) {
    if(new RegExp("("+ k +")").test(format)) {
      format = format.replace(RegExp.$1, RegExp.$1.length==1 ? o[k] : ("00"+ o[k]).substr((""+ o[k]).length));
    }
   }
 return format;
}


function getFile(downUrl){
	//alert('** downUrl = <%=path%>/jsp/DataRequest/downloadFile.jsp?downUrl='+ downUrl);
	window.open("<%=path%>/jsp/DataRequest/downloadFile.jsp?downUrl="+ downUrl);
}


function getOs(){ 
	var OsObject = ""; 
	if(navigator.userAgent.indexOf("MSIE")>0) {
		return "MSIE"; //IE浏览器
	} 
	if(isFirefox=navigator.userAgent.indexOf("Firefox")>0){ 
		return "Firefox"; //Firefox浏览器
	} 
	if(isSafari=navigator.userAgent.indexOf("Safari")>0) { 
		return "Safari"; //Safan浏览器
	} 
	if(isCamino=navigator.userAgent.indexOf("Camino")>0){ 
		return "Camino"; //Camino浏览器
	} 
	if(isMozilla=navigator.userAgent.indexOf("Gecko/")>0){ 
		return "Gecko"; //Gecko浏览器
	}
}

//页面动态调用该函数，动态获取DB中下载链接
function loadXMLDoc(xmlName,dataTypeId){
   	var ivkUrl = "<%=path%>/jsp/DataRequest/autoFindRtnDataGTS.jsp?xmlName=" + xmlName + "&"+ Math.random();
	  //alert("** ivkUrl = "+ ivkUrl);
	  
	  if (window.XMLHttpRequest){
	  	xmlhttp=new XMLHttpRequest();
	  }else if (window.ActiveXObject){
	   	xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
	  }	  
	  
	   if (xmlhttp){
	   		xmlhttp.open("GET",ivkUrl,false);
	   		
	   		btype = getOs();
	   		if(btype != "Firefox"){
	   			xmlhttp.onreadystatechange = state_Change;
	    	}
	    	xmlhttp.send(null);
	    	
	   		if(btype == "Firefox"){
				 	updatePageGTS();
				}
	    
	   }else{
	   	alert("Your browser does not support XMLHTTP");
	   }
	   
	  interval = window.setTimeout("loadXMLDoc('<%=xmlName%>','<%=dataTypeId%>')", 10000);
	  //alert("** interval = "+ interval);
	  	
		//0: 等待；2：数据超大；3：无数据；99：数据获取成功
		if(statusValue < 0){
			window.clearTimeout(interval);
		}else if(statusValue == 2){
			window.clearTimeout(interval);
		}else if(statusValue == 3){
			window.clearTimeout(interval);
		}else if(statusValue == 99){
			window.clearTimeout(interval);
		}
 	}	
 	
 	
 	function state_Change(){
		var dataTypeId = "<%=dataTypeId%>";
						 		
		if (xmlhttp.readyState==4){
			if (xmlhttp.status==200){
				updatePageGTS();
			}else{
				//alert("Problem retrieving XML data");
			}
		}
	}
	
	//动态获取下载状态及下载链接地址
	function updatePageGTS(){
		//alert('updatePageGTS()');
		
		rtnData = eval(xmlhttp.responseText);//获取服务端返回数据(下载链接)
		if(rtnData[0]){
			statusValue = rtnData[0].reqStatus;
			
			if(statusValue < 0){
					document.getElementById("statusGTS").innerHTML = "<strong>Exception</strong>";
					
			}else if(statusValue == 0){
					document.getElementById("statusGTS").innerHTML = "<strong>Being processed</strong>";
								
			}else if(statusValue == 1){
					document.getElementById("statusGTS").innerHTML = "<strong>Begin zip</strong>";
					
			}else if(statusValue == 2){
					document.getElementById("statusGTS").innerHTML = "<strong>The data you requested is too large</strong>";
					
			}else if(statusValue == 3){
					document.getElementById("statusGTS").innerHTML = "<strong>There is no data</strong>";
										
			}else if(statusValue == 99){
					document.getElementById("statusGTS").innerHTML = "<strong>The request is processed successfully</strong>";
										
			}else if(statusValue == 100){
					document.getElementById("statusGTS").innerHTML = "<strong>Being Zipping</strong>";
			
			}else if(statusValue == -99){
					document.getElementById("reqStatus").innerHTML = "<strong>Being Zipping</strong>";
					//document.getElementById("reqStatus").innerHTML = "<strong>Zip Error</strong>";
			}
		}		
		
		for(i = 0; i < rtnData.length; i++){
			if(rtnData[i].downUrl){
				divContent += '<input id="downloadUrl'+ i +'" type="hidden" name="downloadUrl'+ i +'" value="'+ rtnData[i].downUrl +'" >';
				//alert("** divContent = "+ divContent);
			}			
		}
		
		document.getElementById("downUrlHidden").innerHTML = divContent;
		document.getElementById("downloadUrlSize").value = rtnData.length;
		//alert("** downUrlHidden = "+document.getElementById("downUrlHidden").innerHTML);
		//alert("** 下载文件数 = "+ rtnData.length);
		
		
		if(rtnData.length == 1 && rtnData[0].downUrl){//1个下载链接
			rtnData[0].downUrl = '\''+ rtnData[0].downUrl +'\'';
			
			//alert("下载链接: "+ rtnData[0].downUrl);
			document.getElementById("downloadUrlGTS").innerHTML = '<a href="#" onclick="getFile('+ rtnData[0].downUrl +')"><legend>Download results</legend></a>';			
		}
		
		if(rtnData.length > 1){//多个下载链接
			//alert("** 下载连接数:"+　rtnData.length);
			document.getElementById("downloadUrlGTS").innerHTML = '<a href="#" onclick="submitForm()"><legend>Download results</legend></a>';			
		}
	}
  
  	function submitForm(){
		document.mainform.action= "<%=path%>/jsp/DataRequest/downList.jsp";
		document.mainform.submit();
		return true;
	}
	
	//获取服务器端时间,计算和客户端时间差，并在客户端显示
	function showtime(){		
		var str = '<%=serverTime%>';
		var	arr = str.split(" ");
		var arr1 = arr[0].split("-");
		var	arr2 = arr[1].split(":");
		
		var cTime = new Date().format("yyyy-MM-dd hh:mm:ss");
		var	cArr = cTime.split(" ");
		var cArr1 = cArr[0].split("-");
		var	cArr2 = cArr[1].split(":");
		
		//alert('服务端时间：<%=serverTime%>');
		//alert('客户端时间：'+ cTime);
		
		var serverTimes = new Date(arr1[0], arr1[1], arr1[2], arr2[0], arr2[1], arr2[2]);
		var clientTimes = new Date(cArr1[0], cArr1[1], cArr1[2], cArr2[0], cArr2[1], cArr2[2]);
		//alert("** arr2[0]: "+ arr2[0] +"| arr2[1]: "+arr2[1] +"| arr2[2]: "+ arr2[2]);
		//alert("** cArr2[0]: "+ cArr2[0] +"| cArr2[1]: "+cArr2[1] +"| cArr2[2]: "+ cArr2[2]);	
		
		var diff = (clientTimes.valueOf() - serverTimes.valueOf());
		var diffMillions = parseInt(diff,10);
		//alert("时间差: "+ diffMillions);
		
		var currdate = new Date();
		currdate.setTime(currdate.getTime() - diffMillions);
		cTime = currdate.format("yyyy-MM-dd hh:mm:ss");
		
		
		//alert('time1 = ' + document.getElementById('time1'));
		document.getElementById('time1').innerHTML = cTime;
		
		//alert('time2 = ' + document.getElementById('time2'));
		document.getElementById('time2').innerHTML = cTime;
		
		timeTimeout = window.setTimeout("showtime();", 1000); //设定函数自动执行时间为 1000 ms(1 s)		
				
		if(statusValue == 2){
			window.clearTimeout(timeTimeout);
		}else if(statusValue == 3){
			window.clearTimeout(timeTimeout);
		}
		
		if(statusValue == 99 && divContent){//获取到下载链接
			window.clearTimeout(timeTimeout);
		}
	}
  
</script>


//触发动态刷新
<script language="javascript">showtime();</script>
<script language="javascript">loadXMLDoc('<%=xmlName%>','<%=dataTypeId%>');</script>

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