HttpWebRequest myRequest = null;
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。
[原文引至：http://hi.baidu.com/lostparadise/blog/item/f9ff928f58f938f2503d927e.html]