/// <summary>
/// 网络工具类。
/// </summary>
public sealed class WebUtils
{
private int _timeout = 100000;

/// <summary>
/// 请求与响应的超时时间
/// </summary>
public int Timeout
{
get { return this._timeout; }
set { this._timeout = value; }
}

/// <summary>
/// 执行HTTP POST请求。
/// </summary>
/// <param name="url">请求地址</param>
/// <param name="parameters">请求参数</param>
/// <returns>HTTP响应</returns>
public string DoPost(string url, IDictionary<string, string> parameters)
{
HttpWebRequest req = GetWebRequest(url, "POST");
req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";

byte[] postData = http://www.mamicode.com/Encoding.UTF8.GetBytes(BuildQuery(parameters));
System.IO.Stream reqStream = req.GetRequestStream();
reqStream.Write(postData, 0, postData.Length);
reqStream.Close();

HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();
Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);
return GetResponseAsString(rsp, encoding);
}

/// <summary>
/// 执行HTTP GET请求。
/// </summary>
/// <param name="url">请求地址</param>
/// <param name="parameters">请求参数</param>
/// <returns>HTTP响应</returns>
public string DoGet(string url, IDictionary<string, string> parameters)
{
if (parameters != null && parameters.Count > 0)
{
if (url.Contains("?"))
{
url = url + "&" + BuildQuery(parameters);
}
else
{
url = url + "?" + BuildQuery(parameters);
}
}

HttpWebRequest req = GetWebRequest(url, "GET");
req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";

HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();
Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);
return GetResponseAsString(rsp, encoding);
}

/// <summary>
/// 执行带文件上传的HTTP POST请求。
/// </summary>
/// <param name="url">请求地址</param>
/// <param name="textParams">请求文本参数</param>
/// <param name="fileParams">请求文件参数</param>
/// <returns>HTTP响应</returns>
public string DoPost(string url, IDictionary<string, string> textParams, IDictionary<string, FileItem> fileParams)
{
// 如果没有文件参数，则走普通POST请求
if (fileParams == null || fileParams.Count == 0)
{
return DoPost(url, textParams);
}

string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线

HttpWebRequest req = GetWebRequest(url, "POST");
req.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;

System.IO.Stream reqStream = req.GetRequestStream();
byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");
byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");

// 组装文本请求参数
string textTemplate = "Content-Disposition:form-data;name=\"{0}\"\r\nContent-Type:text/plain\r\n\r\n{1}";
IEnumerator<KeyValuePair<string, string>> textEnum = textParams.GetEnumerator();
while (textEnum.MoveNext())
{
string textEntry = string.Format(textTemplate, textEnum.Current.Key, textEnum.Current.Value);
byte[] itemBytes = Encoding.UTF8.GetBytes(textEntry);
reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
reqStream.Write(itemBytes, 0, itemBytes.Length);
}

// 组装文件请求参数
string fileTemplate = "Content-Disposition:form-data;name=\"{0}\";filename=\"{1}\"\r\nContent-Type:{2}\r\n\r\n";
IEnumerator<KeyValuePair<string, FileItem>> fileEnum = fileParams.GetEnumerator();
while (fileEnum.MoveNext())
{
string key = fileEnum.Current.Key;
FileItem fileItem = fileEnum.Current.Value;
string fileEntry = string.Format(fileTemplate, key, fileItem.GetFileName(), fileItem.GetMimeType());
byte[] itemBytes = Encoding.UTF8.GetBytes(fileEntry);
reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
reqStream.Write(itemBytes, 0, itemBytes.Length);

byte[] fileBytes = fileItem.GetContent();
reqStream.Write(fileBytes, 0, fileBytes.Length);
}

reqStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);
reqStream.Close();

HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();
Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);
return GetResponseAsString(rsp, encoding);
}

public bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
{ //直接确认，否则打不开
return true;
}

public HttpWebRequest GetWebRequest(string url, string method)
{
HttpWebRequest req = null;
if (url.Contains("https"))
{
ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
req = (HttpWebRequest)WebRequest.CreateDefault(new Uri(url));
}
else
{
req = (HttpWebRequest)WebRequest.Create(url);
}

req.ServicePoint.Expect100Continue = false;
req.Method = method;
req.KeepAlive = true;
req.UserAgent = "Top4Net";
req.Timeout = this._timeout;

return req;
}

/// <summary>
/// 把响应流转换为文本。
/// </summary>
/// <param name="rsp">响应流对象</param>
/// <param name="encoding">编码方式</param>
/// <returns>响应文本</returns>
public string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
{
System.IO.Stream stream = null;
StreamReader reader = null;

try
{
// 以字符流的方式读取HTTP响应
stream = rsp.GetResponseStream();
reader = new StreamReader(stream, encoding);
return reader.ReadToEnd();
}
finally
{
// 释放资源
if (reader != null) reader.Close();
if (stream != null) stream.Close();
if (rsp != null) rsp.Close();
}
}

/// <summary>
/// 组装GET请求URL。
/// </summary>
/// <param name="url">请求地址</param>
/// <param name="parameters">请求参数</param>
/// <returns>带参数的GET请求URL</returns>
public string BuildGetUrl(string url, IDictionary<string, string> parameters)
{
if (parameters != null && parameters.Count > 0)
{
if (url.Contains("?"))
{
url = url + "&" + BuildQuery(parameters);
}
else
{
url = url + "?" + BuildQuery(parameters);
}
}
return url;
}

/// <summary>
/// 组装普通文本请求参数。
/// </summary>
/// <param name="parameters">Key-Value形式请求参数字典</param>
/// <returns>URL编码后的请求数据</returns>
public static string BuildQuery(IDictionary<string, string> parameters)
{
StringBuilder postData = http://www.mamicode.com/new StringBuilder();
bool hasParam = false;

IEnumerator<KeyValuePair<string, string>> dem = parameters.GetEnumerator();
while (dem.MoveNext())
{
string name = dem.Current.Key;
string value = http://www.mamicode.com/dem.Current.Value;
// 忽略参数名或参数值为空的参数
if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(value))
{
if (hasParam)
{
postData.Append("&");
}

postData.Append(name);
postData.Append("=");
postData.Append(HttpUtility.UrlEncode(value, Encoding.UTF8));
hasParam = true;
}
}

return postData.ToString();
}
}