C#使用GET、POST请求获取结果，这里以一个简单的用户登陆为例。

1、 使用GET请求获取结果

1.1 创建LoginHandler.aspx处理页面

protected void Page_Load(object sender, EventArgs e)
{
    string result = "";
    string userName = Request.QueryString["UserName"];
    string password = Request.QueryString["Password"];

    if (userName == "admin" && password == "")
    {
        result = "登陆成功";
    }
    else
    {
        result = "登陆失败";
    }
    Response.Write(result);
}

1.2 编写GET请求与获取结果方法

/// <summary>
/// GET请求与获取结果
/// </summary>
public static string HttpGet(string Url, string postDataStr)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr == "" ? "" : "?") + postDataStr);
    request.Method = "GET";
    request.ContentType = "text/html;charset=UTF-8";

    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    Stream myResponseStream = response.GetResponseStream();
    StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.UTF8);
    string retString = myStreamReader.ReadToEnd();
    myStreamReader.Close();
    myResponseStream.Close();

    return retString;
}

1.3 调用测试

static void Main(string[] args)
{
    string url = "http://www.mystudy.cn/LoginHandler.aspx";
    string data = "UserName=admin&Password=123";
    string result = HttpGet(url, data);
    Console.WriteLine(result);
    Console.ReadLine();
}

2、 使用POST请求获取结果

2.1 创建LoginHandler.aspx处理页面

protected void Page_Load(object sender, EventArgs e)
{
    string result = "";
    string userName = Request.Form["UserName"];
    string password = Request.Form["Password"];

    if (userName == "admin" && password == "")
    {
        result = "登陆成功";
    }
    else
    {
        result = "登陆失败";
    }
    Response.Write(result);
}

2.2 编写POST请求与获取结果方法

/// <summary>
/// POST请求与获取结果
/// </summary>
public static string HttpPost(string Url, string postDataStr)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";
    request.ContentLength = postDataStr.Length;
    StreamWriter writer = new StreamWriter(request.GetRequestStream(),Encoding.ASCII);//注意编码方式
    writer.Write(postDataStr);
    writer.Flush();
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    string encoding = response.ContentEncoding;
    if (encoding == null || encoding.Length < ) {
        encoding = "UTF-8"; //默认编码
    }
    StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding(encoding));
    string retString = reader.ReadToEnd();
    return retString;
}

2.3 调用测试

static void Main(string[] args)
{
    string url = "http://www.mystudy.cn/LoginHandler.aspx";
    string data = "UserName=admin&Password=123";
    string result = HttpPost(url, data);
    Console.WriteLine(result);
    Console.ReadLine();
}