ajax的json传值方式在jsp页面中的应用

jsp页面：

$(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);
}
}
}
}
}
});
}

此处由于此代码实现的功能是通过ajax定时访问后台hashtable，所以为了是系统区别url不同、ajax返回值不同，特意在url后加上r=+math.random()
java后台处理方法：

/**
* 双服务器九宫格显示
*
* @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;
}
}

关键要把传到jsp的页面存到map中，在通过json传值。
sendmessage.sendobject(map)方法所在类及方法：

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();
}
}