C# http请求相关的函数 HttpWebRequest: Post , Get ; PostAndRedirect

1、 通过HttpWebRequest发起一个Post请求，并获取返回数据

使用指定编码格式发送一个POST请求，并通过约定的编码格式获取返回的数据 

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    /// <summary>
    /// 使用指定编码格式发送一个POST请求，并通过约定的编码格式获取返回的数据
    /// </summary>
    /// <param name="url">请求的url地址</param>
    /// <param name="parameters">请求的参数集合</param>
    /// <param name="reqencode">请求的编码格式</param>
    /// <param name="resencode">接收的编码格式</param>
    /// <returns></returns>
    public static string SendPostRequest(string url, NameValueCollection parameters, Encoding reqencode, Encoding resencode)
    {
        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
        req.Method = "post";
        req.ContentType = "application/x-www-form-urlencoded";

        StringBuilder parassb = new StringBuilder();
        foreach (string key in parameters.Keys)
        {
            if (parassb.Length > 0)
                parassb.Append("&");
            parassb.AppendFormat("{0}={1}", key, parameters[key]);
        }
        byte[] data = reqencode.GetBytes(parassb.ToString());
        Stream reqstream = req.GetRequestStream();
        reqstream.Write(data, 0, data.Length);
        reqstream.Close();
        string result = String.Empty;
        using (StreamReader reader = new StreamReader(req.GetResponse().GetResponseStream(), resencode))
        {
            result = reader.ReadToEnd();
        }
        return result;
    }

2、通过HttpWebRequest发起一个Get请求，并获取返回数据

HttpWebRequest 发送一个GET请求 

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    /*
     * 需要引用如下namespace
     * using System.Reflection;
     * using System.Text;
     * using System.Net;
     * using System.IO;
     */

    /// <summary>
    /// HttpWebRequest 发送一个GET请求
    /// </summary>
    /// <param name="url">请求的url地址</param>
    /// <param name="parameters">请求的参数集合</param>
    /// <param name="reqencode">请求的编码格式</param>
    /// <param name="resencode">接收的编码格式</param>
    /// <returns></returns>
    public static string SendGetRequest(string baseurl, NameValueCollection parameters, Encoding reqencode, Encoding resencode)
    {
        StringBuilder parassb = new StringBuilder();
        foreach (string key in parameters.Keys)
        {
            if (parassb.Length > 0)
                parassb.Append("&");
            parassb.AppendFormat("{0}={1}", HttpUtility.UrlEncode(key, reqencode), HttpUtility.UrlEncode(parameters[key], reqencode));
        }

        if (parassb.Length > 0)
        {
            baseurl += "?" + parassb;
        }
        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(baseurl);
        req.Method = "GET";
        req.MaximumAutomaticRedirections = 3;
        req.Timeout = 5000;

        string result = String.Empty;
        using (StreamReader reader = new StreamReader(req.GetResponse().GetResponseStream(), resencode))
        {
            result = reader.ReadToEnd();
        }
        return result;
    }

3、通过编程的方式实现Post提交请求并重定向至新的URL地址

Post请求并且重定向 

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    /// <summary>
    /// Post请求并且重定向
    /// </summary>
    /// <param name="url"></param>
    /// <param name="parameters"></param>
    /// <param name="context"></param>
    public static void PostAndRedirect(string url, NameValueCollection parameters, HttpContext context)
    {
        StringBuilder script = new StringBuilder();
        script.AppendFormat("<form name=redirpostform action='{0}' method='post'>", url);
        foreach (string key in parameters.Keys)
        {
            script.AppendFormat("<input type='hidden' name='{0}' value='{1}'>",
                key, parameters[key]);
        }
        script.Append("</form>");
        script.Append("<script language='javascript'>redirpostform.submit();</script>");
        context.Response.Write(script);
        context.Response.End();
    }

感谢：http://www.cnblogs.com/didi/archive/2010/06/03/1750723.html