前言：
由于js 远程请求 XMLHttpRequest() 不支持多线程，所以用C# 写了个dll 多线程远程抓住供js调用。
最初代码为：
C#代码
/// <summary>
/// 异步请求入口
/// </summary>
/// <param name="url">传入http地址 注意加http</param>
/// <param name="timeoutStr">超时时间</param>
public void AsyncGet(string url, int timeoutStr)
{
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(url));
request.Timeout = timeoutStr;
request.BeginGetResponse(new AsyncCallback(ReadCallBack), request);
}
catch (Exception) { }
}/// <summary>
/// 执行回调时候异步最终拿到值
/// 正常获取反馈值，异常时候值为 timeout
/// </summary>
public string returnContent { get; set; }/// <summary>
/// 执行异步回调请求
/// </summary>
/// <param name="asynchronousResult"></param>
private void ReadCallBack(IAsyncResult asynchronousResult)
{
try
{
HttpWebRequest reqeust = (HttpWebRequest)asynchronousResult.AsyncState;
HttpWebResponse response = (HttpWebResponse)reqeust.EndGetResponse(asynchronousResult);
StreamReader readContent = new StreamReader(response.GetResponseStream());
returnContent = readContent.ReadToEnd().ToString();
}
catch (Exception)
{
returnContent = "timeout";
}
}
js 代码：
var Gtime = 5;
function getUrl (turl) {
if (Gtime==5) {
comActiveX.AsyncGet(turl,Gtime);
}
if (Gtime>0 && comActiveX.returnContent==undefined) {
setTimeout("getUrl(‘"+turl+"‘)",1000);
alert(comActiveX.returnContent);
Gtime -- ;
}else{
document.write( comActiveX.returnContent);
}
}
这里存在问题，js必须一直去询问dll 是否获取到数据，直到获取到数据才做下面处理，虽然其中可以做其他事情，但是这跟同步等待没有多大区别。
windows 经典编程 有句话叫“don‘t call me , I will call you!”
，这就是事件的引入，那么这里可以不可以优化为，当有数据拿到以后自动通知js，js能不能注册一个回调函数。 开始一通尝试，最终找到相关答案：
C# 加入以下代码：
public delegate void EventHandler(string data);
[Guid("9771B223-6188-4849-B292-C7D9D8173E49")]
[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
public interface ControlEvents
{
[DispId(0x60020000)]
void eventsGet(string data);
}/// <summary>
/// 采集类
/// </summary>
[ClassInterface(ClassInterfaceType.AutoDual), ComSourceInterfaces(typeof(ControlEvents))]
public class CollectGood : UserControl
{public event EventHandler eventsGet;
private delegate void UpEventDelegate(string msg);
public void Reback(string msg)
{
UpEventDelegate up = new UpEventDelegate(UpEvent);
this.BeginInvoke(up, msg);
}
private void UpEvent(string msg)
{
if (eventsGet != null)
{
eventsGet(msg);
}
}#region httpWebRequest 异步请求Get方法
/// <summary>
/// 异步请求入口
/// </summary>
/// <param name="url">传入http地址 注意加http</param>
/// <param name="timeoutStr">超时时间</param>
public void AsyncGet(string url, int timeoutStr)
{
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(url));
request.Timeout = timeoutStr;
request.BeginGetResponse(new AsyncCallback(ReadCallBack), request);
}
catch (Exception) { }
}/// <summary>
/// 执行回调时候异步最终拿到值
/// 正常获取反馈值，异常时候值为 timeout
/// </summary>
public string returnContent { get; set; }/// <summary>
/// 执行异步回调请求
/// </summary>
/// <param name="asynchronousResult"></param>
private void ReadCallBack(IAsyncResult asynchronousResult)
{
try
{
HttpWebRequest reqeust = (HttpWebRequest)asynchronousResult.AsyncState;
HttpWebResponse response = (HttpWebResponse)reqeust.EndGetResponse(asynchronousResult);
StreamReader readContent = new StreamReader(response.GetResponseStream());
returnContent = readContent.ReadToEnd().ToString();
Reback(returnContent);
}
catch (Exception)
{
returnContent = "timeout";
}
}
#endregion
js部分：
<OBJECT id="comActiveX" width="" height="" classid="CLSID:7b8bfbe3-7f62-47e0-919c-6aa2315e6db9">
</OBJECT>
<SCRIPT type="text/javascript">
//var comActiveX;
try {
//comActiveX = new ActiveXObject("HttpAsy.CollectGood");
} catch (e) {
// alert("没有注册好");
}
comActiveX.attachEvent("eventsGet",function(msg){alert(msg)})comActiveX.AsyncGet("http:/www.baidu.com",5);
当运行后就会 弹出 百度源代码
这就实现了异步回调
http://files.cnblogs.com/echosong/http.rar 完整demo下载（先点reg.bat先注册dll）