随笔-348  评论-598  文章-0  trackbacks-0
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。

---------------------------------------------------------
专注移动开发

Android, Windows Mobile, iPhone, J2ME, BlackBerry, Symbian
posted on 2008-09-08 12:52 TiGERTiAN 阅读(7798) 评论(3)  编辑  收藏 所属分类: DotNetWindows Mobile

评论:
# re: HttpWebRequest使用注意(发生阻塞的解决办法)[未登录] 2008-11-08 09:21 | aa
good  回复  更多评论
  
# re: HttpWebRequest使用注意(发生阻塞的解决办法) 2010-02-21 11:03 | OverGame
看了此文才发现错误的所在,谢谢分享  回复  更多评论
  
# re: HttpWebRequest使用注意(发生阻塞的解决办法)[未登录] 2010-06-11 20:42 | Tony
这个问题在PC上还不明显,PC默认能建立25个连接。
但是在Windows Mobile上就很明显了,我在Windows Mobile上做应用,2个request发出后,再发第三个马上就阻塞抽住了,Debugger也无法catch,因为Debugger也要占用连接。
感谢楼主分享。
  回复  更多评论
  

只有注册用户登录后才能发表评论。


网站导航: