ajax 跨域异步调用

涉及到跨域调用时，一般的js ,得不到应有的数据。必须通过UrlConnection来获取到字节数据，来显示出来

思路：当前项目下的js请求到一个jsp页面，在这个jsp上通过urlConnect 链接来获取数据，并根据状态，回写到所要的js调用之处。

function getText(depart){
var url="/.././*.jsp?depart="+depart;
xreq = createXmlHttpRequest();
if (!xreq){
  alert('Giving up Cannot create an XMLHTTP instance');
  return false;
}
var url=url+"&temptime="+Math.random();
xreq.onreadystatechange = showArticleInfo;  //回调函数。
xreq.open('GET', url, true);
xreq.send(null);
}
function showArticleInfo(){
if (xreq.readyState == 4){
  if (xreq.status == 200){
   var articleInfo= xreq.responseText;

//业务处理
    var artId=artInfoArr[0];
    var artTitle=artInfoArr[1];
    var openArticleUrl="/.././*.jsp?art_bh="+artId;
    window.open(openArticleUrl,"newwindow","width=500,height=200,scrollbars=yes,resizable=yes");
   }  
  }
  else if(xreq.status== 500){
   alert('ERRO'+xreq.responseText);
  }
}
}



jsp   //跨域得到数据

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<%
String depart = request.getParameter("depart");
String retArtInfo = "";
if (!(depart == null || depart.trim().equals(""))) {

  String url = "http://外网地址/项目名/*.do?method=*&depart="+depart+"&tamp="+ new Date().getTime();

//方法返回的是串
  URL U = new URL(url);
  String result = "";
  try {
   URLConnection connection = U.openConnection();
   connection.connect();
   BufferedReader in = new BufferedReader(
     new InputStreamReader(connection.getInputStream()));

   String line;

   while ((line = in.readLine()) != null) {
    result += line;
   }
   retArtInfo=result;
   in.close();
   out.clear();
  } catch (Exception e) {

  }

}
out.println(retArtInfo);
%>

ajax 跨域异步调用