mcs/class/referencesource/System.Xml/System/Xml/XmlUrlResolver.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="XmlUrlResolver.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 //------------------------------------------------------------------------------
   7
   8 using System.Threading;
   9 using System.Security.Permissions;
  10 using System.Net;
  11 using System.Net.Cache;
  12 using System.Runtime.Versioning;
  13
  14 namespace System.Xml {
  15
  16     // Resolves external XML resources named by a Uniform Resource Identifier (URI).
  17     public partial class XmlUrlResolver : XmlResolver {
  18         private static object s_DownloadManager;
  19         private ICredentials _credentials;
  20         private IWebProxy _proxy;
  21         private RequestCachePolicy _cachePolicy;
  22
  23         static XmlDownloadManager DownloadManager {
  24             get {
  25                 if ( s_DownloadManager == null ) {
  26                     object dm = new XmlDownloadManager();
  27                     Interlocked.CompareExchange<object>( ref s_DownloadManager, dm, null );
  28                 }
  29                 return (XmlDownloadManager)s_DownloadManager;
  30             }
  31         }
  32
  33         // Construction
  34
  35         // Creates a new instance of the XmlUrlResolver class.
  36         public XmlUrlResolver() {
  37         }
  38
  39         public override ICredentials Credentials {
  40             set { _credentials = value; }
  41         }
  42
  43         public IWebProxy Proxy {
  44             set { _proxy = value; }
  45         }
  46
  47         public RequestCachePolicy CachePolicy {
  48             set { _cachePolicy = value; }
  49         }
  50
  51         // Resource resolution
  52
  53         // Maps a URI to an Object containing the actual resource.
  54         [ResourceConsumption(ResourceScope.Machine)]
  55         [ResourceExposure(ResourceScope.Machine)]
  56         public override Object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn) {
  57             if (ofObjectToReturn == null || ofObjectToReturn == typeof(System.IO.Stream) || ofObjectToReturn == typeof(System.Object)) {
  58                 return DownloadManager.GetStream(absoluteUri, _credentials, _proxy, _cachePolicy);
  59             }
  60             else {
  61                 throw new XmlException(Res.Xml_UnsupportedClass, string.Empty);
  62             }
  63         }
  64
  65         [PermissionSetAttribute(SecurityAction.InheritanceDemand, Name = "FullTrust")]
  66         [ResourceConsumption(ResourceScope.Machine)]
  67         [ResourceExposure(ResourceScope.Machine)]
  68         public override Uri ResolveUri(Uri baseUri, string relativeUri){
  69             return base.ResolveUri(baseUri, relativeUri);
  70         }
  71     }
  72 }