Http异步发送之HttpWebRequest的BeginGetResponse

关于http异步发送,一开始我的做法都是用thread或者task去完成的;后来发现HttpWebRequest本身就提供一个异步的方法。

总感觉.Net自己提供的异步方法可能要优于我们自己用线程去实现的好;

当然这只是我的猜想。个人感觉如果有大量异步发送还是用HttpWebRequest本身提供的异步方法好。

自己封装了下HttpWebRequest的异步请求。

  1         /// <summary>
  2         /// http异步请求
  3         /// </summary>
  4         /// <param name="url">url</param>
  5         /// <param name="reqMethod">请求方法 GET、POST</param>
  6         /// <param name="callback">回调函数</param>
  7         /// <param name="ob">回传对象</param>
  8         /// <param name="postData">post数据</param>
  9         public static void HttpAsyncRequest(string url, string reqMethod, AsyRequetCallback callback, object ob = null, string postData = "")
 10         {
 11             Stream requestStream = null;
 12             try
 13             {
 14                 HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
 15                 request.ContentType = "application/x-www-form-urlencoded";
 16                 request.Method = reqMethod;
 17                 if (reqMethod.ToUpper() == "POST")
 18                 {
 19                     byte[] bytes = Encoding.UTF8.GetBytes(postData);
 20                     request.ContentLength = bytes.Length;
 21                     requestStream = request.GetRequestStream();
 22                     requestStream.Write(bytes, 0, bytes.Length);
 23                 }
 24                 //开始调用异步请求 
 25                 //AsyResultTag 是自定义类 用于传递调用时信息 其中HttpWebRequest 是必须传递对象。
 26                 //因为回调需要用HttpWebRequest来获取HttpWebResponse 
 27                 request.BeginGetResponse(new AsyncCallback(HttpCallback), new AsyResultTag() { obj = ob, callback = callback, req = request });
 28             }
 29             catch (Exception ex)
 30             {
 31                 throw ex;
 32             }
 33             finally
 34             {
 35                 if (requestStream != null)
 36                 {
 37                     requestStream.Close();
 38                 }
 39             }
 40         }
 41 
 42 
 43         /// <summary>
 44         /// http请求回调 由.net内部调用 参数必须为IAsyncResult
 45         /// </summary>
 46         /// <param name="asynchronousResult">http回调时回传对象</param>
 47         private static void HttpCallback(IAsyncResult asynchronousResult)
 48         {
 49             int statusCode = 0;
 50             string retString = "";
 51             AsyResultTag tag = new AsyResultTag();
 52             WebException webEx = null;
 53             try
 54             {
 55                 //获取请求时传递的对象
 56                 tag = asynchronousResult.AsyncState as AsyResultTag;
 57                 HttpWebRequest req = tag.req;
 58                 //获取异步返回的http结果
 59                 HttpWebResponse response = req.EndGetResponse(asynchronousResult) as HttpWebResponse;
 60                 Stream myResponseStream = response.GetResponseStream();
 61                 StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
 62                 retString = myStreamReader.ReadToEnd();
 63                 myStreamReader.Close();
 64                 myResponseStream.Close();
 65                 statusCode = ((int)response.StatusCode);
 66 
 67             }
 68             catch (WebException ex)
 69             {
 70                 if ((HttpWebResponse)ex.Response != null)
 71                 {
 72                     statusCode = ((int)((HttpWebResponse)ex.Response).StatusCode);
 73                 }
 74                 
 75                 webEx = ex;
 76             }
 77             //调用外部回调 即最外层的回调
 78             tag.callback(tag.obj, retString, statusCode, webEx);
 79 
 80         }
 81 
 82        /// <summary>
 83        /// 异步请求回调委托
 84        /// </summary>
 85       /// <param name="asyObj">回传对象</param>
 86       /// <param name="resStr">http响应结果</param>
 87       /// <param name="statusCode">http状态码</param>
 88       /// <param name="webEx">异常</param>
 89       public delegate void AsyRequetCallback(object asyObj, string respStr, int statusCode, WebException webEx);
 90 
 91      /// <summary>
 92      /// 异步返回对象
 93      /// </summary>
 94      class AsyResultTag
 95      {
 96         /// <summary>
 97         /// 回传对象
 98         /// </summary>
 99         public object obj { get; set; }
100         /// <summary>
101         /// 当前httpRequest请求实例
102         /// </summary>
103         public HttpWebRequest req { get; set; }
104         /// <summary>
105         /// 回调函数委托
106         /// </summary>
107         public AsyRequetCallback callback { get; set; }
108      }
AsyRequetCallback 异步回调委托,即要回调的函数原型;说下每个参数的意义:

1、object asyObj:
回传对象,即请求时附带的一个对象,如果没有可以不用传。比如我们当前的这个请求和用户有所关联,如当前的这个请求对应是某个用户的,请求后我要将结果写到这个用户的某个属性下面;这样我们就可以将此用户信息和当前请求一起携带过去。
2、string respStr:当前http返回结果。

3、int statusCode:http状态码,包括出错时的状态码。如404,403等。

4、WebException webEx 异常信息,异常信息也会随着回调传递到前面来,不直接向上抛或者直接log。好处在于,我们可以针对这个异常信息做单独处理。比如某个用户如果碰到什么403或者404我们应该怎么处理,又或者我们可以将错误信息随着当前用户进行保存,很好的跟踪每个用户的发送情况。



 

posted @ 2017-07-01 21:59  Cfan1236  阅读(716)  评论(3编辑  收藏