求HTTP C# 下载类

求HTTP C# 下载类

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Net;

namespace WebGatherClass
{
///

/// 采集方法集合
///

public class WebGatherFunction
{
///

/// 获取网页html信息
/// 如果errStr != String.Empty,则表示获取错误。
///

/// 网址
/// Post数据
/// 错误信息返回
///
public static string GetPostPageHtml(string url, string postData, out string errStr)
{
errStr = string.Empty;
Stream outstream = null;
Stream instream = null;
StreamReader sr = null;
HttpWebResponse response = null;
HttpWebRequest request = null;
Encoding encoding = Encoding.Default;
byte[] data = encoding.GetBytes(postData);

try
{
// 设置参数
request = WebRequest.Create(url) as HttpWebRequest;
CookieContainer cookieContainer = new CookieContainer();
request.CookieContainer = cookieContainer;
request.AllowAutoRedirect = true;
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = data.Length;
outstream = request.GetRequestStream();
outstream.Write(data, 0, data.Length);
outstream.Close();

//发送请求并获取相应回应数据
response = request.GetResponse() as HttpWebResponse;

//直到request.GetResponse()程序才开始向目标网页发送Post请求
instream = response.GetResponseStream();
sr = new StreamReader(instream, encoding);

//返回结果网页（html）代码
string content = sr.ReadToEnd();
return content.ToLower();
}
catch (Exception ex)
{
errStr = ex.Message;
return null;
}
finally
{
if (outstream != null)
{
outstream.Close();
}
if (instream != null)
{
instream.Close();
}
if (sr != null)
{
sr.Close();
}
if (response != null)
{
response.Close();
}
if (request != null)
{
request = null;
}
}
}

///

/// 获取网页html信息
/// 如果errStr != String.Empty,则表示获取错误。
///

/// 网址
/// 错误信息返回
/// 网页编码
///
public static string GetPageHtml(string url, string encodingStr, out string errStr)
{
errStr = string.Empty;
WebRequest myReq = null;
WebResponse webResponse = null;
try
{
myReq = WebRequest.Create(url);

webResponse = myReq.GetResponse();
}
catch (Exception ex)
{
errStr = ex.Message;
return null;
}

String charset = null;
Encoding e = null;
if (charset == null)
{
//如果发现content-type头
String ctype = webResponse.Headers["content-type"];
if (ctype != null)
{
int ind = ctype.IndexOf("charset=");
if (ind != -1)
{
charset = ctype.Substring(ind + 8);
}
}
}

Stream resStream = null;
StreamReader sr = null;
try
{
resStream = webResponse.GetResponseStream();

MemoryStream rawdata = new MemoryStream();
byte[] buffer = new byte[1024];
int read = resStream.Read(buffer, 0, buffer.Length);
while (read > 0)
{
rawdata.Write(buffer, 0, read);
read = resStream.Read(buffer, 0, buffer.Length);
}

//如果没有发现content-type，只好从脚本中搜索了
if (charset == null)
{
rawdata.Seek(0, SeekOrigin.Begin);

StreamReader srr = new StreamReader(rawdata, Encoding.ASCII);
String meta = srr.ReadToEnd().ToLower();

if (meta != null)
{
int start_ind = meta.IndexOf("charset=");
int end_ind = -1;
if (start_ind != -1)
{
end_ind = meta.IndexOf("\"", start_ind);
if (end_ind != -1)
{
int start = start_ind + 8;
charset = meta.Substring(start, end_ind - start + 1);
charset = charset.TrimEnd(new Char[] { '>', '"' }).Trim();
}
}

if (charset == null)
{
start_ind = meta.IndexOf("encoding=");
end_ind = -1;
if (start_ind != -1)
{
end_ind = meta.IndexOf("?", start_ind);
if (end_ind != -1)
{
int start = start_ind + 9;
charset = meta.Substring(start, end_ind - start);
charset = charset.Trim(new Char[] { '\'', '"' }).Trim();

}
}
}
}
}

if (charset == null)
{
try
{
e = Encoding.GetEncoding(encodingStr);
}
catch
{
e = Encoding.UTF8;
}
}
else if (e == null)
{
try
{
e = Encoding.GetEncoding(charset);
}
catch
{
try
{
e = Encoding.GetEncoding(encodingStr);
}
catch
{
e = Encoding.UTF8;
}
}
}

rawdata.Seek(0, SeekOrigin.Begin);
sr = new StreamReader(rawdata, e);
string htmlStr = sr.ReadToEnd();

rawdata.Close();
resStream.Close();
webResponse.Close();

return htmlStr;
}
catch (Exception ex)
{
errStr = ex.Message;
return null;
}
finally
{
webResponse.Close();
if (resStream != null)
{
resStream.Close();
}
if (sr != null)
{
sr.Close();
}
}
}

///

/// 获取网页html信息
/// 如果errStr != String.Empty,则表示获取错误。
///

/// 网址
/// 编码格式
/// 错误信息返回
///
public static string GetPageHtmlByEncoding(string url, string encodingStr, out string errStr)
{
errStr = string.Empty;

Stream resStream = null;
StreamReader sr = null;
try
{
WebRequest myReq = WebRequest.Create(url);

using (WebResponse webResponse = myReq.GetResponse())
{
String charset = encodingStr;
resStream = webResponse.GetResponseStream();

MemoryStream rawdata = new MemoryStream();
byte[] buffer = new byte[1024];
int read = resStream.Read(buffer, 0, buffer.Length);
while (read > 0)
{
rawdata.Write(buffer, 0, read);
read = resStream.Read(buffer, 0, buffer.Length);
}

Encoding encoding = null;

try
{
encoding = Encoding.GetEncoding(charset);
}
catch
{
encoding = Encoding.UTF8;
}

rawdata.Seek(0, SeekOrigin.Begin);
sr = new StreamReader(rawdata, encoding);
string htmlStr = sr.ReadToEnd();

rawdata.Close();
resStream.Close();
webResponse.Close();

return htmlStr;
}
}
catch (Exception ex)
{
errStr = ex.Message;
return null;
}
finally
{
if (resStream != null)
{
resStream.Close();
}
if (sr != null)
{
sr.Close();
}
}

}

///

/// 下载图片到本地目录
///

///
///
///
internal static bool RequestWebImg(string imgUrl, string imgSavePath)
{
try
{
WebClient client = new WebClient();

client.DownloadFile(imgUrl, imgSavePath);
return true;
}
catch
{
return false;
}
}

///

/// 下载图片到本地目录
///

///
///
///
internal static bool DownLoadWebImg(string imgUrl, string imgSavePath)
{
HttpWebRequest myReq = null;
HttpWebResponse webResponse = null;
try
{
myReq = (HttpWebRequest)HttpWebRequest.Create(imgUrl);
myReq.AllowAutoRedirect = true;
webResponse = (HttpWebResponse)myReq.GetResponse();
}
catch
{
return false;
}

int bufferSize = 1024;
byte[] buffer = new byte[bufferSize];
int readBytes = 0;
try
{
using (FileStream stream = new FileStream(imgSavePath, FileMode.Append))
{
Stream sr = null;
try
{
sr = webResponse.GetResponseStream();
do
{
readBytes = sr.Read(buffer, 0, bufferSize);
stream.Write(buffer, 0, readBytes);
}
while (readBytes != 0);
}
catch
{
return false;
}
finally
{
try
{
sr.Close();
stream.Close();
}
catch
{
}
}
return true;
}
}
catch
{
return false;
}
}
}
}

有了就不贴了@

WebClient也行啊