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();
}
}
大家看下這段程序，有問題嗎？乍一看，好像沒有什么問題，所有的流都釋放了，Response也釋放了。。不過如果你寫個(gè)循環(huán)無限次發(fā)起請(qǐng)求，你會(huì)發(fā)現(xiàn)，運(yùn)行不了幾次就阻塞了。為什么呢？大家看下面的代碼
HttpWebRequest myRequest = null;
HttpWebResponse myResponse = null;
Stream reqStream = null;
Stream resStream = null;
try
{
byte[] data = System.Text.Encoding.Default.GetBytes(param);
//想服務(wù)器端發(fā)送請(qǐng)求，獲取照片信息
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？多了這個(gè)
if (myRequest != null)
{
myRequest.Abort();
}
其實(shí)很多時(shí)候釋放了Stream和Response還不夠，客戶端的Request還是在保持著，需要等垃圾回收器來回收，所以一般很容易阻塞，導(dǎo)致請(qǐng)求發(fā)送不出去。加上這個(gè)就是讓HttpWebRequest實(shí)例在不需要的時(shí)候及時(shí)釋放資源。這樣可以重復(fù)使用而不會(huì)阻塞。
---------------------------------------------------------
專注移動(dòng)開發(fā)
Android, Windows Mobile, iPhone, J2ME, BlackBerry, Symbian
posted on 2008-09-08 12:52
TiGERTiAN 閱讀(7865)
評(píng)論(3) 編輯 收藏 所屬分類:
DotNet 、
Windows Mobile