本文实例讲述了C#实现可缓存网页到本地的反向代理工具。分享给大家供大家参考。具体实现方法如下：
proxy.ashx 主文件：
<%@ WebHandler Language="C#" Class="proxy" %>
using System;
using System.Web;
using System.Net;
using System.Text;
using System.IO;
using System.Collections.Generic;
using System.Configuration;
/// <summary>
/// 把http headers 和 http 响应的内容 分别存储在 /proxy/header/ 和 /proxy/body/ 中
/// 分层次创建目录
/// </summary>
public class proxy : IHttpHandler
{
HttpResponse Response;
HttpRequest Request;
HttpApplicationState Application;
HttpServerUtility Server;
static string proxyCacheFolder = ConfigurationManager.AppSettings["proxyCacheFolder"];
static string proxyDomain = ConfigurationManager.AppSettings["proxyDomain"];
static string proxyReferer = ConfigurationManager.AppSettings["proxyReferer"];
bool proxyCacheDirectAccess = ConfigurationManager.AppSettings["proxyCacheDirectAccess"] == "true";
int proxyCacheSeconds = int.Parse(ConfigurationManager.AppSettings["proxyCacheSeconds"]);
public void ProcessRequest(HttpContext context)
{
Response = context.Response;
Request = context.Request;
Application = context.Application;
Server = context.Server;
string path = context.Request.RawUrl;
bool delCache = path.IndexOf("?del") > 0;
if (delCache)
{
path = path.Replace("?del", string.Empty);
DeleteCacheFile(path);
return;
}
bool allowCache = Request.QueryString["cache"] == "true";
string seconds = Request.QueryString["seconds"] ?? string.Empty;
if (!int.TryParse(seconds, out proxyCacheSeconds))
{
proxyCacheSeconds = 3600;
}
if (allowCache)
{
EchoData(path);
}
else
{
WebClient wc = new WebClient();
wc.Headers.Set("Referer", proxyReferer);
byte[] buffer = wc.DownloadData(proxyDomain + path);
Response.ContentType = wc.ResponseHeaders["Content-Type"];
foreach (string key in wc.ResponseHeaders.AllKeys)
{
Response.Headers.Set(key, wc.ResponseHeaders[key]);
}
wc.Dispose();
Response.OutputStream.Write(buffer, 0, buffer.Length);
}
}
/// <summary>
/// 清理失效的缓存
/// </summary>
/// <param name="d"></param>
void ClearTimeoutCache(DirectoryInfo d)
{
if (d.Exists)
{
FileInfo[] files = d.GetFiles();
foreach (FileInfo file in files)
{
TimeSpan timeSpan = DateTime.Now - file.LastAccessTime;
if (timeSpan.TotalSeconds > proxyCacheSeconds)
{
file.Delete();
}
}
}
}
string GetCacheFolderPath(string hash)
{
string s = string.Empty;
for (int i = 0; i <= 2; i++)
{
s += hash[i] + "/";
}
return s;
}
/// <summary>
/// 读取缓存的header 并输出
/// </summary>
/// <param name="cacheHeaderPath"></param>
void EchoCacheHeader(string cacheHeaderPath)
{
string[] headers = File.ReadAllLines(cacheHeaderPath);
for (int i = 0; i < headers.Length; i++)
{
string[] headerKeyValue = headers[i].Split(':');
if (headerKeyValue.Length == 2)
{
if (headerKeyValue[0] == "Content-Type")
{
Response.ContentType = headerKeyValue[1];
}
Response.Headers.Set(headerKeyValue[0], headerKeyValue[1]);
}
}
}
void DeleteCacheFile(string path)
{
string absFolder = Server.MapPath(proxyCacheFolder);
string hash = GetHashString(path);
string folder = GetCacheFolderPath(hash);
string cacheBodyPath = absFolder + "/body/" + folder + hash;
string cacheHeaderPath = absFolder + "/header/" + folder + hash;
FileInfo cacheBody = new FileInfo(cacheBodyPath);
FileInfo cacheHeader = new FileInfo(cacheHeaderPath);
if (cacheBody.Exists)
{
cacheBody.Delete();
}
if (cacheHeader.Exists)
{
cacheHeader.Delete();
}
Response.Write("delete cache file Success!\r\n" + path);
}
/// <summary>
/// 输出缓存
/// </summary>
/// <param name="cacheHeaderPath">缓存header 的文件路径</param>
/// <param name="cacheBodyPath">缓存 body 的文件路径</param>
/// <param name="ifTimeout">是否进行判断文件过期</param>
/// <returns>是否输出成功</returns>
bool EchoCacheFile(string cacheHeaderPath, string cacheBodyPath, bool ifTimeout)
{
FileInfo cacheBody = new FileInfo(cacheBodyPath);
FileInfo cacheHeader = new FileInfo(cacheHeaderPath);
ClearTimeoutCache(cacheBody.Directory);
ClearTimeoutCache(cacheHeader.Directory);
if (cacheBody.Exists && cacheHeader.Exists)
{
if (ifTimeout)
{
TimeSpan timeSpan = DateTime.Now - cacheBody.LastWriteTime;
if (timeSpan.TotalSeconds < proxyCacheSeconds)
{
EchoCacheHeader(cacheHeaderPath);
Response.TransmitFile(cacheBodyPath);
return true;
}
}
else
{
EchoCacheHeader(cacheHeaderPath);
Response.TransmitFile(cacheBodyPath);
return true;
}
}
return false;
}
void EchoData(string path)
{
string absFolder = Server.MapPath(proxyCacheFolder);
string hash = GetHashString(path);
string folder = GetCacheFolderPath(hash);
string cacheBodyPath = absFolder + "/body/" + folder + hash;
string cacheHeaderPath = absFolder + "/header/" + folder + hash;
bool success;
if (proxyCacheDirectAccess)
{
success = EchoCacheFile(cacheHeaderPath, cacheBodyPath, false);
if (!success)
{
Response.Write("直接从缓存读取失败!");
}
return;
}
success = EchoCacheFile(cacheHeaderPath, cacheBodyPath, true);
if (success)
{
return;
}
//更新Cache File
string ApplicationKey = "CacheList";
List<string> List = null;
if (Application[ApplicationKey] == null)
{
Application.Lock();
Application[ApplicationKey] = List = new List<string>(1000);
Application.UnLock();
}
else
{
List = (List<string>)Application[ApplicationKey];
}
//判断是否已有另一个进程正在更新Cache File
if (List.Contains(hash))
{
success = EchoCacheFile(cacheHeaderPath, cacheBodyPath, false);
if (success)
{
return;
}
else
{
WebClient wc = new WebClient();
wc.Headers.Set("Referer", proxyReferer);
//主体内容
byte[] data = wc.DownloadData(proxyDomain + path);
//处理header
Response.ContentType = wc.ResponseHeaders["Content-Type"];
foreach (string key in wc.ResponseHeaders.AllKeys)
{
Response.Headers.Set(key, wc.ResponseHeaders[key]);
}
wc.Dispose();
Response.BinaryWrite(data);
}
}
else
{
WebClient wc = new WebClient();
wc.Headers.Set("Referer", proxyReferer);
StringBuilder headersb = new StringBuilder();
List.Add(hash);
//主体内容
byte[] data = wc.DownloadData(proxyDomain + path);
//处理header
Response.ContentType = wc.ResponseHeaders["Content-Type"];
foreach (string key in wc.ResponseHeaders.AllKeys)
{
headersb.Append(key);
headersb.Append(":");
headersb.Append(wc.ResponseHeaders[key]);
headersb.Append("\r\n");
Response.Headers.Set(key, wc.ResponseHeaders[key]);
}
wc.Dispose();
string headers = headersb.ToString().Trim();
if (!Directory.Exists(absFolder + "/header/" + folder))
{
Directory.CreateDirectory(absFolder + "/header/" + folder);
}
StreamWriter sw = File.CreateText(absFolder + "/header/" + folder + hash);
sw.Write(headers);
sw.Close();
sw.Dispose();
//处理缓存内容
if (!Directory.Exists(absFolder + "/body/" + folder))
{
Directory.CreateDirectory(absFolder + "/body/" + folder);
}
FileStream fs = File.Create(absFolder + "/body/" + folder + hash);
fs.Write(data, 0, data.Length);
fs.Close();
fs.Dispose();
List.Remove(hash);
Response.BinaryWrite(data);
}
}
string GetHashString(string path)
{
string md5 = GetMd5Str(path);
return md5;
}
static string GetMd5Str(string ConvertString)
{
System.Security.Cryptography.MD5CryptoServiceProvider md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(ConvertString)), 4, 8);
t2 = t2.Replace("-", "");
return t2;
}
public bool IsReusable
{
get
{
return false;
}
}
}
web.config文件如下：
<?xml version="1.0"?> <configuration> <configSections> <section name="RewriterConfig" type="URLRewriter.Config.RewriterConfigSerializerSectionHandler, URLRewriter"/> </configSections> <RewriterConfig> <Rules> <RewriterRule> <LookFor>~/.*$</LookFor> <SendTo> <!--cache=true 设置此路径进行缓存--> <![CDATA[~/proxy.ashx?cache=true&seconds=30]]> </SendTo> </RewriterRule> <RewriterRule> <LookFor>~/ajax/.*$</LookFor> <SendTo> <!--cache=false 设置此路径不允许缓存--> <![CDATA[~/proxy.ashx?cache=false]]> </SendTo> </RewriterRule> </Rules> </RewriterConfig> <appSettings> <!--#反向代理设置 start--> <!--设置站点--> <add key="proxyDomain" value="http://127.0.0.1:12123/"/> <!--缓存文件夹--> <add key="proxyCacheFolder" value="/proxyCache/"/> <!--缓存时长--> <add key="proxyCacheSeconds" value="3600"/> <!--设置不再判断缓存文件是否超时，直接从缓存读取--> <add key="proxyCacheDirectAccess" value="false"/> <!--设置反向代理Referer--> <add key="proxyReferer" value="http://www.www.com/"/> <!--#反向代理设置 end--> </appSettings> <system.webServer> <modules runAllManagedModulesForAllRequests="true"> <add type="URLRewriter.ModuleRewriter, URLRewriter" name="ModuleRewriter"/> </modules> </system.webServer> <system.web> <compilation debug="true"/> </system.web> </configuration>
希望本文所述对大家的C#程序设计有所帮助。
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