WebClient 非常慢
我的网络客户端有问题。
它非常慢。从一个网站下载String大约需要3-5秒。 我没有任何网络问题。
这是我修改后的 WebClient。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
namespace StatusChecker
{
class WebClientEx: WebClient
{
public CookieContainer CookieContainer { get; private set; }
public WebClientEx()
{
CookieContainer = new CookieContainer();
ServicePointManager.Expect100Continue = false;
Encoding = System.Text.Encoding.UTF8;
WebRequest.DefaultWebProxy = null;
Proxy = null;
}
public void ClearCookies()
{
CookieContainer = new CookieContainer();
}
protected override WebRequest GetWebRequest(Uri address)
{
var request = base.GetWebRequest(address);
if (request is HttpWebRequest)
{
(request as HttpWebRequest).CookieContainer = CookieContainer;
}
return request;
}
}
}
更新： 在wireshark中，我看到单个DownladString正在发送和接收数千个数据包。
I have problem with Webclient.
It is very slow. It takes about 3-5 seconds to downloadString from one website.
I don't have any network problems.
This is my Modifed WebClient.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
namespace StatusChecker
{
class WebClientEx: WebClient
{
public CookieContainer CookieContainer { get; private set; }
public WebClientEx()
{
CookieContainer = new CookieContainer();
ServicePointManager.Expect100Continue = false;
Encoding = System.Text.Encoding.UTF8;
WebRequest.DefaultWebProxy = null;
Proxy = null;
}
public void ClearCookies()
{
CookieContainer = new CookieContainer();
}
protected override WebRequest GetWebRequest(Uri address)
{
var request = base.GetWebRequest(address);
if (request is HttpWebRequest)
{
(request as HttpWebRequest).CookieContainer = CookieContainer;
}
return request;
}
}
}
UPDATE:
In wireshark I saw that single DownladString is sending and receiving few thousands packets.
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评论（3）
这里可能存在两个问题（我之前在自己的程序中也注意到过）：
WebRequest默认情况下会在第一次启动时检测并加载代理设置，这可能需要相当长的时间。要阻止这种情况，只需将代理属性 (WebRequest.Proxy) 设置为null，它将绕过检查（前提是您可以直接访问互联网）ServicePointManager.DefaultConnectionLimit设置为更大的值。我通常将其设置为int.MaxValue（只要确保您不会向主机发送垃圾邮件，连接数为 1,000,000）。There may be two issues at hand here (that I've also noticed in my own programs previously):
WebRequestby default detects and loads proxy settings the first time it starts, which can take quite a while. To stop this, simply set the proxy property (WebRequest.Proxy) tonulland it'll bypass the check (provided you can directly access the internet)ServicePointManager.DefaultConnectionLimitto something larger. I usually set this toint.MaxValue(just make sure you don't spam the host with 1,000,000 connections).如果与检查的初始代理设置相关，有几个选项：
将代理设置为空：
WebClient.Proxy = null
应用程序启动时将默认 Web 代理设置为 null：
WebRequest.DefaultWebProxy = null;
在较旧的 .NET 代码中，您通常会这样写（但现在首选 null），而不是设置为 null：
There are a few options if it is related to the initial proxy settings being checked:
Set the proxy to null:
WebClient.Proxy = null
On application startup set the default webproxy to null:
WebRequest.DefaultWebProxy = null;
In older .NET code instead of setting to null, you used to write this (but null is now preferred):
也许它会对某人有所帮助。某些 Web 服务支持压缩（gzip 或其他）。因此，您可以为请求添加 Accept-Encoding 标头，然后启用自动解压缩 用于 Web 客户端实例。 Chrome 就是这样工作的。
Maybe it will help somebody. Some web services support compression (gzip or other). So you can add Accept-Encoding header for your requests and then enable automatic decompression for web client instance. Chrome works in that way.