HttpWebRequest使用注意（发生阻塞的解决办法）
HttpWebResponse myResponse = null; Stream reqStream = null; Stream resStream = null; try { byte[] data = System.Text.Encoding.Default.GetBytes(param); myRequest = (HttpWebRequest)WebRequest.Create(url); myRequest.Method = "POST"; myRequest.KeepAlive = true; myRequest.ContentType = "application/octet-stream"; myRequest.ContentLength = data.Length; reqStream = myRequest.GetRequestStream(); reqStream.Write(data, 0, data.Length); reqStream.Close(); myResponse = (HttpWebResponse)myRequest.GetResponse(); resStream = myResponse.GetResponseStream(); data = new byte[512]; int count = 0; UIFactory.zZRK_MODIForm.memStream = new MemoryStream(); while ((count = resStream.Read(data, 0, data.Length)) > 0) { UIFactory.zZRK_MODIForm.memStream.Write(data, 0, count); } resStream.Close(); } catch { } finally { if (resStream != null) { resStream.Close(); } if (reqStream != null) { reqStream.Close(); } if (myResponse != null) { myResponse.Close(); } }
大家看下这段程序，有问题吗？乍一看，好像没有什么问题，所有的流都释放了，Response也释放了。。不过如果你写个循环无限次发起请求，你会发现，运行不了几次就阻塞了。为什么呢？大家看下面的代码
HttpWebRequest myRequest = null; HttpWebResponse myResponse = null; Stream reqStream = null; Stream resStream = null; try { byte[] data = System.Text.Encoding.Default.GetBytes(param); //想服务器端发送请求，获取照片信息 myRequest = (HttpWebRequest)WebRequest.Create(url); myRequest.Method = "POST"; myRequest.KeepAlive = true; myRequest.ContentType = "application/octet-stream"; myRequest.ContentLength = data.Length; reqStream = myRequest.GetRequestStream(); reqStream.Write(data, 0, data.Length); reqStream.Close(); myResponse = (HttpWebResponse)myRequest.GetResponse(); resStream = myResponse.GetResponseStream(); data = new byte[512]; int count = 0; UIFactory.zZRK_MODIForm.memStream = new MemoryStream(); while ((count = resStream.Read(data, 0, data.Length)) > 0) { UIFactory.zZRK_MODIForm.memStream.Write(data, 0, count); } resStream.Close(); } catch { } finally { if (resStream != null) { resStream.Close(); } if (reqStream != null) { reqStream.Close(); } if (myResponse != null) { myResponse.Close(); } if (myRequest != null) { myRequest.Abort(); } }
多了些什么？多了这个
if (myRequest != null){myRequest.Abort();}
其实很多时候释放了Stream和Response还不够，客户端的Request还是在保持着，需要等垃圾回收器来回收，所以一般很容易阻塞，导致请求发送不出去。加上这个就是让HttpWebRequest实例在不需要的时候及时释放资源。这样可以重复使用而不会阻塞。
