HttpRequest.MapPath 方法

參考

定義

命名空間:: System.Web

組件:: System.Web.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

將用戶端目前要求之 URL 的虛擬路徑對應至伺服器上的實體路徑。

多載

MapPath(String)	將指定的虛擬路徑對應至實體路徑。
MapPath(String, String, Boolean)	將指定的虛擬路徑對應至實體路徑。

MapPath(String)

將指定的虛擬路徑對應至實體路徑。

public:
 System::String ^ MapPath(System::String ^ virtualPath);

public string MapPath (string virtualPath);

member this.MapPath : string -> string

Public Function MapPath (virtualPath As String) As String

參數

virtualPath: String

目前要求的虛擬路徑 (絕對或相對的)。

傳回

String

伺服器上的實體路徑，由 virtualPath 所指定。

例外狀況

HttpException

未定義要求的 HttpContext 物件。

範例

下列程式碼範例會使用方法， MapPath 將虛擬路徑轉換成伺服器上的完整實體路徑。此範例有兩個部分：

.aspx 頁面會對應路徑、讀取檔案，並顯示讀取作業的結果。
類別 UpperCaseFilterStream ，會將傳遞至大寫的所有字元變更為大寫。

範例的第一個部分示範如何使用方法，將虛擬路徑轉換為完整實體路徑 MapPath 。然後，這個實體路徑會傳遞至 StreamReader 物件，以取得檔案的內容。 Write接著會呼叫方法，以顯示頁面上檔案的內容。屬性 Filter 是用來將篩選附加至回應資料流程，讓文字顯示至頁面全部大寫。

<%@ Page Language="C#" %>
<%@ Import Namespace="System.IO" %>
<%@ import Namespace="Samples.AspNet.CS.Controls"  %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    private void Page_Load(object sender, EventArgs e)
    {

      // Filter the text to be rendered as all uppercase.
      Response.Filter = new UpperCaseFilterStream(Response.Filter);

      // Convert a virtual path to a fully qualified physical path.
      string fullpath = Request.MapPath("~\\TestFile.txt");

      try
      {
        // Read the contents of the file using a StreamReader.
        using (StreamReader sr = new StreamReader(fullpath))
        while (sr.Peek() >= 0)
        {
          Response.Write((char)sr.Read());
        }
        Message.Text = "Reading the file was successful.";
        
      }
      catch (Exception ex)
      {
        Message.Text = "The process failed.";
      }    
     }

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>HttpResponse.MapPath Example</title>
  </head>
  <body>
    <form id="form1" runat="server">

      <asp:Label id="Message" 
                 runat="server"/>

    </form>
  </body>
</html>

<%@ Page Language="VB" Debug="true"%>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="Samples.AspNet.VB.Controls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
     
  Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
      
    ' Filter the text to be rendered as all uppercase.
    Response.Filter = New UpperCaseFilterStream(Response.Filter)
    
    ' Convert a virtual path to a fully qualified physical path.
    Dim fullpath As String = Request.MapPath("~\\TestFile.txt")
    
    Try
      
      Dim sr As StreamReader = New StreamReader(fullpath)
      
      Do While sr.Peek() >= 0
        Response.Write(Convert.ToChar(sr.Read()))
      Loop
      sr.Close()
      Message.Text = "Reading the file was successful."
      
    Catch ex As Exception
      
      Message.Text = "The process failed."

    End Try

    
  End Sub

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>HttpResponse.MapPath Example</title>
  </head>
  <body>
    <form id="Form1" runat="server">

      <asp:Label id="Message" 
                 runat="server"/>

    </form>
  </body>
</html>

此範例的第二個部分顯示繼承自 Stream 的類別，並將資料流程中的所有字元轉換成大寫。將此程式碼放在 App_Code 您應用程式的資料夾中。


using System;
using System.IO;
using System.Text;

namespace Samples.AspNet.CS.Controls
{

   public class UpperCaseFilterStream : Stream
   // This filter changes all characters passed through it to uppercase.
   {
      private Stream strSink;
      private long lngPosition;

      public UpperCaseFilterStream(Stream sink)
      {
          strSink = sink;
      }

      // The following members of Stream must be overriden.
      public override bool CanRead
      {
         get { return true; }
      }

      public override bool CanSeek
      {
         get { return true; }
      }

      public override bool CanWrite
      {
         get { return true; }
      }

      public override long Length
      {
         get { return 0; }
      }

      public override long Position
      {
         get { return lngPosition; }
         set { lngPosition = value; }
      }

      public override long Seek(long offset, System.IO.SeekOrigin direction)
      {
         return strSink.Seek(offset, direction);
      }

      public override void SetLength(long length)
      {
         strSink.SetLength(length);
      }

      public override void Close()
      {
         strSink.Close();
      }

      public override void Flush()
      {
         strSink.Flush();
      }

      public override int Read(byte[] buffer, int offset, int count)
      {
         return strSink.Read(buffer, offset, count);
      }

      // The Write method actually does the filtering.
      public override void Write(byte[] buffer, int offset, int count)
      {
         byte[] data = new byte[count];
         Buffer.BlockCopy(buffer, offset, data, 0, count);
         string inputstring = Encoding.ASCII.GetString(data).ToUpper();
         data = Encoding.ASCII.GetBytes(inputstring);
         strSink.Write(data, 0, count);
      }
   }
}

Imports System.IO
Imports System.Text


Namespace Samples.AspNet.VB.Controls

    Public Class UpperCaseFilterStream
        Inherits Stream

        ' This filter changes all characters passed through it to uppercase.
        Private strSink As Stream
        Private lngPosition As Long


        Public Sub New(ByVal sink As Stream)
            strSink = sink
        End Sub

        ' The following members of Stream must be overriden.  
        Public Overrides ReadOnly Property CanRead() As Boolean
            Get
                Return True
            End Get
        End Property

        Public Overrides ReadOnly Property CanSeek() As Boolean
            Get
                Return True
            End Get
        End Property

        Public Overrides ReadOnly Property CanWrite() As Boolean
            Get
                Return True
            End Get
        End Property

        Public Overrides ReadOnly Property Length() As Long
            Get
                Return 0
            End Get
        End Property

        Public Overrides Property Position() As Long
            Get
                Return lngPosition
            End Get
            Set(ByVal value As Long)
                lngPosition = Value
            End Set
        End Property

        Public Overrides Function Seek( _
        ByVal offset As Long, ByVal direction As System.IO.SeekOrigin) As Long
            Return strSink.Seek(offset, direction)
        End Function 'Seek


        Public Overrides Sub SetLength(ByVal length As Long)
            strSink.SetLength(length)
        End Sub


        Public Overrides Sub Close()
            strSink.Close()
        End Sub


        Public Overrides Sub Flush()
            strSink.Flush()
        End Sub


        Public Overrides Function Read( _
        ByVal buffer() As Byte, ByVal offset As Integer, ByVal count As Integer) As Integer
            Return strSink.Read(buffer, offset, count)
        End Function 'Read


        ' The Write method actually does the filtering.
        Public Overrides Sub Write( _
        ByVal buffer() As Byte, ByVal offset As Integer, ByVal count As Integer)

            Dim data(count) As Byte
            System.Buffer.BlockCopy(buffer, offset, data, 0, count)
            Dim inputstring As String = Encoding.ASCII.GetString(data).ToUpper()
            data = Encoding.ASCII.GetBytes(InputString)
            strSink.Write(data, 0, count)

        End Sub

    End Class

End Namespace

備註

警告

屬性 MapPath 可能包含有關裝載環境的敏感性資訊。不應向使用者顯示傳回值。

適用於

MapPath(String, String, Boolean)

將指定的虛擬路徑對應至實體路徑。

public:
 System::String ^ MapPath(System::String ^ virtualPath, System::String ^ baseVirtualDir, bool allowCrossAppMapping);

public string MapPath (string virtualPath, string baseVirtualDir, bool allowCrossAppMapping);

member this.MapPath : string * string * bool -> string

Public Function MapPath (virtualPath As String, baseVirtualDir As String, allowCrossAppMapping As Boolean) As String

參數

virtualPath: String

目前要求的虛擬路徑 (絕對或相對的)。

baseVirtualDir: String

用於相對解析的虛擬基底目錄路徑。

allowCrossAppMapping: Boolean

true 表示 virtualPath 可能屬於另一個應用程式；否則為 false。

傳回

String

伺服器的實體路徑。

例外狀況

HttpException

allowCrossMapping 是 false，而且 virtualPath 屬於另一個應用程式。

-或-

未定義要求的 HttpContext 物件。

備註

警告

屬性 MapPath 可能包含有關裝載環境的敏感性資訊。不應向使用者顯示傳回值。

適用於

HttpRequest.MapPath 方法

定義

多載

MapPath(String)

參數

傳回

例外狀況

範例

備註

適用於

MapPath(String, String, Boolean)

參數

傳回

例外狀況

備註

適用於

其他資源