HttpContext 类 作用

 HttpContext 类:封装有关个别 HTTP 请求的所有 HTTP 特定的信息.也有人叫上下文信息.

    1.生存周期:从客户端用户点击并产生了一个向服务器发送请求开始---服务器处理完请求并生成返回到客户端为止.
      注:针对每个不同用户的请求,服务器都会创建一个新的HttpContext实例直到请求结束,服务器销毁这个实例.
    2.为什么会有HttpContext类呢:在ASP年代,大家都是通过在.asp页面的代码中使用Request,Respose,Server等等这些Http特定信息的.但在ASP.NET时代,这中方式已经无法满足应用,(比如我们要在IHttpModule中处理Request时,我们使用什么方法来获取呢?于是就产生了HttpContext类,它对Request,Respose,Server等等都进行了封装,并保证在整个请求周期内都可以随时随地的调用.)
    3.特殊性:当然HttpContext不仅仅只有这点功能.ASP.NET中它还提供了很多特殊的功能.例如Cache.还有HttpContext.Item,通过它你可以在HttpContext的生存周期内提前存储一些临时的数据,方便随时使用.具体的大家还是参考上面的MSDN提供内容.

 

实际用处：

在业务层需要取得当前页面层的Session，Request，Response，Server时可以通过Http.Current来获得。

/// RequestHelper 的摘要说明。
/// 请求类
/// </summary>
public class RequestHelper
{
public RequestHelper()
{
//
// TODO: 在此处添加构造函数逻辑
//
}

/**//// <summary>
/// 判断当前页面是否接收到了Post请求
/// </summary>
/// <returns>是否接收到了Post请求</returns>
public static bool IsPost()
{
return HttpContext.Current.Request.HttpMethod.Equals("POST");
}
/**//// <summary>
/// 判断当前页面是否接收到了Get请求
/// </summary>
/// <returns>是否接收到了Get请求</returns>
public static bool IsGet()
{
return HttpContext.Current.Request.HttpMethod.Equals("GET");
}

/**//// <summary>
/// 返回指定的服务器变量信息
/// </summary>
/// <param name="strName">服务器变量名</param>
/// <returns>服务器变量信息</returns>
public static string GetServerString(string strName)
{
//
if (HttpContext.Current.Request.ServerVariables[strName] == null)
{
return "";
}
return HttpContext.Current.Request.ServerVariables[strName].ToString();
}

/**//// <summary>
/// 返回上一个页面的地址
/// </summary>
/// <returns>上一个页面的地址</returns>
public static string GetUrlReferrer()
{
string retVal = null;

try
{
retVal = HttpContext.Current.Request.UrlReferrer.ToString();
}
catch{}

if (retVal == null)
return "";

return retVal;

}

/**//// <summary>
/// 得到当前完整主机头
/// </summary>
/// <returns></returns>
public static string GetCurrentFullHost()
{
HttpRequest request = System.Web.HttpContext.Current.Request;
if (!request.Url.IsDefaultPort)
{
return string.Format("{0}:{1}", request.Url.Host, request.Url.Port.ToString());
}
return request.Url.Host;
}

/**//// <summary>
/// 得到主机头
/// </summary>
/// <returns></returns>
public static string GetHost()
{
return HttpContext.Current.Request.Url.Host;
}

/**//// <summary>
/// 获取当前请求的原始 URL(URL 中域信息之后的部分,包括查询字符串(如果存在))
/// </summary>
/// <returns>原始 URL</returns>
public static string GetRawUrl()
{
return HttpContext.Current.Request.RawUrl;
}

/**//// <summary>
/// 判断当前访问是否来自浏览器软件
/// </summary>
/// <returns>当前访问是否来自浏览器软件</returns>
public static bool IsBrowserGet()
{
string[] BrowserName = {"ie", "opera", "netscape", "mozilla"};
string curBrowser = HttpContext.Current.Request.Browser.Type.ToLower();
for (int i = 0; i < BrowserName.Length; i++)
{
if (curBrowser.IndexOf(BrowserName[i]) >= 0)
{
return true;
}
}
return false;
}

/**//// <summary>
/// 判断是否来自搜索引擎链接
/// </summary>
/// <returns>是否来自搜索引擎链接</returns>
public static bool IsSearchEnginesGet()
{
string[] SearchEngine = {"google", "yahoo", "msn", "baidu", "sogou", "sohu", "sina", "163", "lycos", "tom"};
string tmpReferrer = HttpContext.Current.Request.UrlReferrer.ToString().ToLower();
for (int i = 0; i < SearchEngine.Length; i++)
{
if (tmpReferrer.IndexOf(SearchEngine[i]) >= 0)
{
return true;
}
}
return false;
}

/**//// <summary>
/// 获得当前完整Url地址
/// </summary>
/// <returns>当前完整Url地址</returns>
public static string GetUrl()
{
return HttpContext.Current.Request.Url.ToString();
}

/**//// <summary>
/// 获得指定Url参数的值
/// </summary>
/// <param name="strName">Url参数</param>
/// <returns>Url参数的值</returns>
public static string GetQueryString(string strName)
{
if (HttpContext.Current.Request.QueryString[strName] == null)
{
return "";
}
return HttpContext.Current.Request.QueryString[strName];
}

/**//// <summary>
/// 获得当前页面的名称
/// </summary>
/// <returns>当前页面的名称</returns>
public static string GetPageName()
{
string [] urlArr = HttpContext.Current.Request.Url.AbsolutePath.Split('/');
return urlArr[urlArr.Length - 1].ToLower();
}

/**//// <summary>
/// 返回表单或Url参数的总个数
/// </summary>
/// <returns></returns>
public static int GetParamCount()
{
return HttpContext.Current.Request.Form.Count + HttpContext.Current.Request.QueryString.Count;
}

/**//// <summary>
/// 获得指定表单参数的值
/// </summary>
/// <param name="strName">表单参数</param>
/// <returns>表单参数的值</returns>
public static string GetFormString(string strName)
{
if (HttpContext.Current.Request.Form[strName] == null)
{
return "";
}
return HttpContext.Current.Request.Form[strName];
}

/**//// <summary>
/// 获得Url或表单参数的值, 先判断Url参数是否为空字符串, 如为True则返回表单参数的值
/// </summary>
/// <param name="strName">参数</param>
/// <returns>Url或表单参数的值</returns>
public static string GetString(string strName)
{
if ("".Equals(GetQueryString(strName)))
{
return GetFormString(strName);
}
else
{
return GetQueryString(strName);
}
}

/**//// <summary>
/// 获得指定Url参数的int类型值
/// </summary>
/// <param name="strName">Url参数</param>
/// <param name="defValue">缺省值</param>
/// <returns>Url参数的int类型值</returns>
public static int GetQueryInt(string strName, int defValue)
{
return Utils.StrToInt(HttpContext.Current.Request.QueryString[strName], defValue);
}

/**//// <summary>
/// 获得指定表单参数的int类型值
/// </summary>
/// <param name="strName">表单参数</param>
/// <param name="defValue">缺省值</param>
/// <returns>表单参数的int类型值</returns>
public static int GetFormInt(string strName, int defValue)
{
return Utils.StrToInt(HttpContext.Current.Request.Form[strName], de
b2fa
fValue);
}

/**//// <summary>
/// 获得指定Url或表单参数的int类型值, 先判断Url参数是否为缺省值, 如为True则返回表单参数的值
/// </summary>
/// <param name="strName">Url或表单参数</param>
/// <param name="defValue">缺省值</param>
/// <returns>Url或表单参数的int类型值</returns>
public static int GetInt(string strName, int defValue)
{
if (GetQueryInt(strName, defValue) == defValue)
{
return GetFormInt(strName, defValue);
}
else
{
return GetQueryInt(strName, defValue);
}
}

/**//// <summary>
/// 获得指定Url参数的float类型值
/// </summary>
/// <param name="strName">Url参数</param>
/// <param name="defValue">缺省值</param>
/// <returns>Url参数的int类型值</returns>
public static float GetQueryFloat(string strName, float defValue)
{
return Utils.StrToFloat(HttpContext.Current.Request.QueryString[strName], defValue);
}

/**//// <summary>
/// 获得指定表单参数的float类型值
/// </summary>
/// <param name="strName">表单参数</param>
/// <param name="defValue">缺省值</param>
/// <returns>表单参数的float类型值</returns>
public static float GetFormFloat(string strName, float defValue)
{
return Utils.StrToFloat(HttpContext.Current.Request.Form[strName], defValue);
}

/**//// <summary>
/// 获得指定Url或表单参数的float类型值, 先判断Url参数是否为缺省值, 如为True则返回表单参数的值
/// </summary>
/// <param name="strName">Url或表单参数</param>
/// <param name="defValue">缺省值</param>
/// <returns>Url或表单参数的int类型值</returns>
public static float GetFloat(string strName, float defValue)
{
if (GetQueryFloat(strName, defValue) == defValue)
{
return GetFormFloat(strName, defValue);
}
else
{
return GetQueryFloat(strName, defValue);
}
}

/**//// <summary>
/// 获得当前页面客户端的IP
/// </summary>
/// <returns>当前页面客户端的IP</returns>
public static string GetIP()
{

string result = String.Empty;

result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (null == result || result == String.Empty)
{
result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
}

if (null == result || result == String.Empty)
{
result = HttpContext.Current.Request.UserHostAddress;
}

if (null == result || result == String.Empty)
{
return "0.0.0.0";
}

return result;

}

/**//// <summary>
/// 保存用户上传的文件
/// </summary>
/// <param name="path">保存路径</param>
public static void SaveRequestFile(string path)
{
if (HttpContext.Current.Request.Files.Count > 0)
{
HttpContext.Current.Request.Files[0].SaveAs(path);
}
}

}
 http://blog.csdn.net/mych/archive/2008/05/07/2407409.aspx[/code]