ajax的json傳值方式在jsp頁面中的應用

$(document).ready(function() { 
setInterval(function myTimer() 
{ 
//alert('a'); 
getViews(); 
},1000); 
}); 
//播放 
function getViews(){ 
$.ajax({ 
'url':"${pageContext.request.contextPath}/video/getVideos.action?r="+Math.random()+"&open=1", 
'data': '', 
'dataType': 'json', 
'type': 'get', 
'error': function(data){ 
alert("error"); 
return false; 
}, 
'success': function(data) { 
if(null != data && '' != data){ 
//alert(data.updateFlag); 
if(data.updateFlag==0){//如果data.updateFlag=0 不刷新 
//alert("data.updateFlag=0"); 
} 
else{ 
if(data.videoIds != null && data.videoIds != ""){ 
var listIds=data.videoIds; 
var i=0; 
for(;i<listIds.length;++i){ 
//alert("show:"+i+"id=:"+listIds[i]); 
showView(listIds[i],i);//播放 
} 
for(var j=listIds.length;j<9;++j){ 
//alert("Stop:"+j); 
StopPlayVideo(j); 
} 
} 
} 
} 
} 
}); 
} 
 
此處由于此代碼實現的功能是通過ajax定時訪問后臺Hashtable，所以為了是系統區別url不同、ajax返回值不同，特意在url后加上r=+Math.random() 
java后臺處理方法： 
 代碼如下:

/** 
* 雙服務器九宮格顯示 
* 
* @return 
*/ 
@Action(value = "getVideos" ,results={ 
@Result(name = SUCCESS,location="videos2.jsp") 
}) 
public String getVideos() { 
if (open == 301) { 
return SUCCESS; 
} else { 
try { 
VideoHashTable videoHashTable = VideoHashTable.getInstance(); 
Hashtable<Long, Long> hashTable = videoHashTable.getRht(); 
Map map = new HashMap<String, List<Long>>(); 
if (videoHashTable.isUpdateFlag() == true) { 
Enumeration en = hashTable.keys(); 
videoIds = new ArrayList<Long>(); 
while (en.hasMoreElements()) { 
Long key = (Long) en.nextElement(); 
// vth.get(key); 
videoIds.add(key); 
} 
map.put("videoIds", videoIds); 
map.put("updateFlag", 1L); 
videoHashTable.setUpdateFlag(false); 
System.out.println("getVideos:" + videoIds); 
SendMessage.sendObject(map); 
} else { 
map.put("updateFlag", 0L); 
SendMessage.sendObject(map); 
} 
} catch (Exception e) { 
e.printStackTrace(); 
} 
return null; 
} 
} 
 
關鍵要把傳到jsp的頁面存到map中，在通過json傳值。 
SendMessage.sendObject(map)方法所在類及方法： 
 代碼如下:

package com.supcon.honcomb.utils; 
import java.io.IOException; 
import java.io.PrintWriter; 
import javax.servlet.http.HttpServletResponse; 
import org.apache.http.HttpResponse; 
import org.apache.struts2.ServletActionContext; 
public class SendMessage { 
public static void sendMessage(String responseText){ 
try { 
PrintWriter out = ServletActionContext.getResponse().getWriter(); 
out.print(responseText); 
out.close(); 
} catch (IOException e) { 
e.printStackTrace(); 
} 
} 
public static void sendObject(Object obj) throws Exception { 
PrintWriter pw; 
String rtn = ""; 
HttpServletResponse response = ServletActionContext.getResponse(); 
response.setContentType("text/html"); 
response.setCharacterEncoding("UTF-8"); 
rtn = JsonUtil.JsonFromObject(obj); 
pw = response.getWriter(); 
pw.write(rtn); 
pw.flush(); 
pw.close(); 
} 
} 

 
 




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