UnauthorizedAccessException 类

定义

public ref class UnauthorizedAccessException : SystemException

[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public class UnauthorizedAccessException : SystemException

type UnauthorizedAccessException = class
    inherit SystemException

Public Class UnauthorizedAccessException
Inherits SystemException

继承

Object

Exception

SystemException

UnauthorizedAccessException

派生

System.Security.AccessControl.PrivilegeNotHeldException

属性

ComVisibleAttribute SerializableAttribute

示例

下面的示例演示尝试UnauthorizedAccessException写入只读文件时引发的异常。The following example illustrates the UnauthorizedAccessException exception that is thrown when attempting to write to a read-only file.

using System;
using System.IO;

public class Example
{
   public static void Main()
   {
      string filePath = @".\ROFile.txt";
      if (! File.Exists(filePath))
         File.Create(filePath);
      // Keep existing attributes, and set ReadOnly attribute.
      File.SetAttributes(filePath, 
                        (new FileInfo(filePath)).Attributes | FileAttributes.ReadOnly);

      StreamWriter sw = null;
      try {
         sw = new StreamWriter(filePath);
         sw.Write("Test");
      }
      catch (UnauthorizedAccessException) {
         FileAttributes attr = (new FileInfo(filePath)).Attributes;
         Console.Write("UnAuthorizedAccessException: Unable to access file. ");
         if ((attr & FileAttributes.ReadOnly) > 0)
            Console.Write("The file is read-only."); 
       }
       finally {
         if (sw != null) sw.Close();
      }   
   }
}
// The example displays the following output:
//    UnAuthorizedAccessException: Unable to access file. The file is read-only.

Imports System.IO

Module Example
   Public Sub Main()
      Dim filePath As String = ".\ROFile.txt"
      If Not File.Exists(filePath) Then File.Create(filePath)
      ' Keep existing attributes, and set ReadOnly attribute.
      File.SetAttributes(filePath, 
                        (New FileInfo(filePath)).Attributes Or FileAttributes.ReadOnly)

      Dim sw As StreamWriter = Nothing
      Try
         sw = New StreamWriter(filePath)
         sw.Write("Test")
      Catch e As UnauthorizedAccessException
         Dim attr As FileAttributes = (New FileInfo(filePath)).Attributes
         Console.Write("UnAuthorizedAccessException: Unable to access file. ")
         If (attr And FileAttributes.ReadOnly) > 0 Then
            Console.Write("The file is read-only.") 
         End If
       Finally
         If sw IsNot Nothing Then sw.Close()
      End Try   
   End Sub
End Module
' The example displays the following output:
'   UnAuthorizedAccessException: Unable to access file. The file is read-only.

注解

通常情况下, 包装 Windows API 调用的方法会引发异常。UnauthorizedAccessExceptionAn UnauthorizedAccessException exception is typically thrown by a method that wraps a Windows API call. 若要查找异常的原因, 请检查异常对象Message的属性的文本。To find the reasons for the exception, examine the text of the exception object's Message property.

UnauthorizedAccessExceptionHRESULT 使用,COR_E_UNAUTHORIZEDACCESS其值为0x80070005。UnauthorizedAccessException uses the HRESULT COR_E_UNAUTHORIZEDACCESS, which has the value 0x80070005.

构造函数

属性

方法

事件

适用于

另请参阅

• Exception
• 处理和引发异常Handling and Throwing Exceptions