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using
System;using
System.Collections.Generic;using
System.Linq;using
System.Text;using
System.Net;using
System.IO;using
System.Threading;namespace
AsncyHandle{ public
class RequestState { const
int BUFFER_SIZE = 1024; public
StringBuilder RequestData; public
byte[] BufferRead; public
HttpWebRequest Request; public
Stream ResponseStream; //创建适当编码类型的解码器 public
Decoder StreamDecode = Encoding.UTF8.GetDecoder(); public
RequestState() { BufferRead = new
byte[BUFFER_SIZE]; RequestData = new
StringBuilder(""); Request = null; ResponseStream = null; } } class
Program { public
static ManualResetEvent allDone = new
ManualResetEvent(false); const
int BUFFER_SIZE = 1024; static
void Main(string[] args) { //创建请求对象 HttpWebRequest wreq = (HttpWebRequest)WebRequest.Create(HttpSite); //创建请求对象 RequestState rs = new
RequestState(); //将请求添加到状态，以便可以被来回传涕 rs.Request = wreq; //发出异步请求 IAsyncResult r = (IAsyncResult)wreq.BeginGetResponse(new
AsyncCallback(RespCallback), rs); // 将 ManualResetEvent 设置为 Wait， // 以便在调用回调前，应用程序不退出 allDone.WaitOne(); } public
static void showusage() { Console.WriteLine("尝试获取 (GET) 一个 URL"); Console.WriteLine("\r\n用法：:"); Console.WriteLine("ClientGetAsync URL"); Console.WriteLine("示例：:"); } public
static void RespCallback(IAsyncResult ar) { //从异步结果获取RequestState 对象 RequestState rs = (RequestState)ar.AsyncState; //从RequestState 获取HttpWebRequest HttpWebRequest req = rs.Request; //调用 EndGetResponse 生成 HttpWebResponse 对象 HttpWebResponse resp = (HttpWebResponse)req.EndGetResponse(ar); // // 既然我们拥有了响应，就该从 // 响应流开始读取数据了 Stream responseStream = resp.GetResponseStream(); //该读取操作也使用异步完成，所以我们 //将要以 RequestState 存储流 rs.ResponseStream = responseStream; // 请注意，rs.BufferRead 被传入到 BeginRead。 // 这是数据将被读入的位置。 IAsyncResult iarRead = responseStream.BeginRead(rs.BufferRead, 0, BUFFER_SIZE, new
AsyncCallback(ReadCallBack), rs); } private
static void ReadCallBack(IAsyncResult asyncResult) { //从asyncresult 获取 RequestState 对象 RequestState rs = (RequestState)asyncResult.AsyncState; //取出在respCallBack 中设置的ResponseStream Stream responseStream = rs.ResponseStream; int
read = responseStream.EndRead(asyncResult); if
(read > 0) { //准备Char数组缓冲区，用于向Unicode 转换 Char[] charBuffer = new
Char[BUFFER_SIZE]; //将字节流转换为Char 数组，然后转换为字符串 //len 显示多少字符被转换为 unicode int
len = rs.StreamDecode.GetChars(rs.BufferRead, 0, read, charBuffer, 0); String str = new
String(charBuffer, 0, len); //将最近读取的数据追加到RequestData stirngBuilder对象中 //该对想包含在RequestState中 rs.RequestData.Append(str); IAsyncResult ar = responseStream.BeginRead(rs.BufferRead, 0, BUFFER_SIZE, new
AsyncCallback(ReadCallBack), rs); } else { if(rs.RequestData.Length>1) { //所有数据都已被读取，因此将其显示 到控制台 string
strContent; strContent = rs.RequestData.ToString(); Console.WriteLine(strContent); } //关闭响应流 responseStream.Close(); //设置ManualResetEvent ,以便主线程可以退出 allDone.Set(); } return; } }} |
原文：http://www.cnblogs.com/xuehaiyiye/p/3566709.html