【C#】HTTP请求GET，POST

HTTP定义了与服务器交互的不同方法，基本方法有GET，POST，PUT，DELETE，分别对于查，该，增，删。一般情况下我们只用到GET和POST，其他两种都也可以用GET和POST来实现，很多浏览器也只实现了GET和POST两种方法

　　GET：用户获取信息

　　　　安全的：不会对服务器上的数据进行修改，和破坏

　　　　幂等的：相同的请求所返回的结果相同

　　　　参数是通过Url来传输，接在Url后面中间用?分开，不同参数之间用&分开，下面表示传递两个参数param1和param2，值为value1和value2

　　　　　　http://songurl/index.htm?param1=value1¶m2=value2

　　　　通过上面可以看到，GET请求数据在隐私方面又是不安全的，因为Url上的信息可以直接让用户看到，这样不利于隐私保护

　　POST：用于更新数据

　　　　传递的数据对用户隐藏，封装在包里，具体看演示

　　　　有时候请求会重定向，但我们就需要从重定向url获取东西，这时可以设置重定向禁用，你就可以从headers的Location属性中获取重定向地址

　　　　　　request.AllowAutoRedirect = false;

　　　　　　string[] values = request.Headers.GetValues("Location");

下面是辅助类的定义

public class HttpHelper
{
/// <summary>
/// 创建GET方式的HTTP请求
/// </summary>
public static HttpWebResponse CreateGetHttpResponse(string url, int timeout, string userAgent, CookieCollection cookies)
{
HttpWebRequest request = null;
if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
{
//对服务端证书进行有效性校验（非第三方权威机构颁发的证书，如自己生成的，不进行验证，这里返回true）
ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
request = WebRequest.Create(url) as HttpWebRequest;
request.ProtocolVersion = HttpVersion.Version10;    //http版本，默认是1.1,这里设置为1.0
}
else
{
request = WebRequest.Create(url) as HttpWebRequest;
}
request.Method = "GET";

//设置代理UserAgent和超时
//request.UserAgent = userAgent;
//request.Timeout = timeout;
if (cookies != null)
{
request.CookieContainer = new CookieContainer();
request.CookieContainer.Add(cookies);
}
return request.GetResponse() as HttpWebResponse;
}

/// <summary>
/// 创建POST方式的HTTP请求
/// </summary>
public static HttpWebResponse CreatePostHttpResponse(string url, IDictionary<string, string> parameters, int timeout, string userAgent, CookieCollection cookies)
{
HttpWebRequest request = null;
//如果是发送HTTPS请求
if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
{
//ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
request = WebRequest.Create(url) as HttpWebRequest;
//request.ProtocolVersion = HttpVersion.Version10;
}
else
{
request = WebRequest.Create(url) as HttpWebRequest;
}
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";

//设置代理UserAgent和超时
//request.UserAgent = userAgent;
//request.Timeout = timeout;

if (cookies != null)
{
request.CookieContainer = new CookieContainer();
request.CookieContainer.Add(cookies);
}
//发送POST数据
if (!(parameters == null || parameters.Count == 0))
{
StringBuilder buffer = new StringBuilder();
int i = 0;
foreach (string key in parameters.Keys)
{
if (i > 0)
{
buffer.AppendFormat("&{0}={1}", key, parameters[key]);
}
else
{
buffer.AppendFormat("{0}={1}", key, parameters[key]);
i++;
}
}
byte[] data = Encoding.ASCII.GetBytes(buffer.ToString());
using (Stream stream = request.GetRequestStream())
{
stream.Write(data, 0, data.Length);
}
}
string[] values = request.Headers.GetValues("Content-Type");
return request.GetResponse() as HttpWebResponse;
}

/// <summary>
/// 获取请求的数据
/// </summary>
public static string GetResponseString(HttpWebResponse webresponse)
{
using (Stream s = webresponse.GetResponseStream())
{
StreamReader reader = new StreamReader(s, Encoding.UTF8);
return reader.ReadToEnd();

}
}

/// <summary>
/// 验证证书
/// </summary>
private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
{
if (errors == SslPolicyErrors.None)
return true;
return false;
}
}