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Uri Class

Provides an object representation of a uniform resource identifier (URI) and easy access to the parts of the URI.

Namespace:  System
Assembly:  System (in System.dll)
[SerializableAttribute]
[TypeConverterAttribute(typeof(UriTypeConverter))]
public ref class Uri : ISerializable

The Uri type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUri(String)Initializes a new instance of the Uri class with the specified URI.
Protected methodUri(SerializationInfo, StreamingContext)Initializes a new instance of the Uri class from the specified instances of the SerializationInfo and StreamingContext classes.
Public methodSupported by the XNA FrameworkUri(String, Boolean) Obsolete. Initializes a new instance of the Uri class with the specified URI, with explicit control of character escaping.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUri(String, UriKind)Initializes a new instance of the Uri class with the specified URI. This constructor allows you to specify if the URI string is a relative URI, absolute URI, or is indeterminate.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUri(Uri, String)Initializes a new instance of the Uri class based on the specified base URI and relative URI string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUri(Uri, Uri)Initializes a new instance of the Uri class based on the combination of a specified base Uri instance and a relative Uri instance.
Public methodSupported by the XNA FrameworkUri(Uri, String, Boolean) Obsolete. Initializes a new instance of the Uri class based on the specified base and relative URIs, with explicit control of character escaping.
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  NameDescription
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsAbsolutePathGets the absolute path of the URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsAbsoluteUriGets the absolute URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsAuthorityGets the Domain Name System (DNS) host name or IP address and the port number for a server.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsDnsSafeHostGets an unescaped host name that is safe to use for DNS resolution.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFragmentGets the escaped URI fragment.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsHostGets the host component of this instance.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsHostNameTypeGets the type of the host name specified in the URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsAbsoluteUriGets whether the Uri instance is absolute.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsDefaultPortGets whether the port value of the URI is the default for this scheme.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsFileGets a value indicating whether the specified Uri is a file URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsLoopbackGets whether the specified Uri references the local host.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsUncGets whether the specified Uri is a universal naming convention (UNC) path.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLocalPathGets a local operating-system representation of a file name.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsOriginalStringGets the original URI string that was passed to the Uri constructor.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsPathAndQueryGets the AbsolutePath and Query properties separated by a question mark (?).
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsPortGets the port number of this URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsQueryGets any query information included in the specified URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsSchemeGets the scheme name for this URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsSegmentsGets an array containing the path segments that make up the specified URI.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUserEscapedIndicates that the URI string was completely escaped before the Uri instance was created.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUserInfoGets the user name, password, or other user-specific information associated with the specified URI.
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  NameDescription
Protected methodSupported by the XNA FrameworkCanonicalizeInfrastructure. Obsolete. Converts the internally stored URI to canonical form.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCheckHostNameDetermines whether the specified host name is a valid DNS name.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCheckSchemeNameDetermines whether the specified scheme name is valid.
Protected methodSupported by the XNA FrameworkCheckSecurityInfrastructure. Obsolete. Calling this method has no effect.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompareCompares the specified parts of two URIs using the specified comparison rules.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEqualsCompares two Uri instances for equality. (Overrides Object::Equals(Object).)
Protected methodSupported by the XNA FrameworkEscapeInfrastructure. Obsolete. Converts any unsafe or reserved characters in the path component to their hexadecimal character representations.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEscapeDataStringConverts a string to its escaped representation.
Protected methodStatic memberSupported by the XNA FrameworkEscapeString Obsolete. Converts a string to its escaped representation.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEscapeUriStringConverts a URI string to its escaped representation.
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodStatic memberSupported by the XNA FrameworkFromHexGets the decimal value of a hexadecimal digit.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetComponentsGets the specified components of the current instance using the specified escaping for special characters.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetHashCodeGets the hash code for the URI. (Overrides Object::GetHashCode().)
Public methodSupported by the XNA FrameworkGetLeftPartGets the specified portion of a Uri instance.
Protected methodGetObjectDataReturns the data needed to serialize the current instance.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodStatic memberSupported by the XNA FrameworkHexEscapeConverts a specified character into its hexadecimal equivalent.
Public methodStatic memberSupported by the XNA FrameworkHexUnescapeConverts a specified hexadecimal representation of a character to the character.
Protected methodSupported by the XNA FrameworkIsBadFileSystemCharacterInfrastructure. Obsolete. Gets whether a character is invalid in a file system name.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsBaseOfDetermines whether the current Uri instance is a base of the specified Uri instance.
Protected methodStatic memberSupported by the XNA FrameworkIsExcludedCharacterInfrastructure. Obsolete. Gets whether the specified character should be escaped.
Public methodStatic memberSupported by the XNA FrameworkIsHexDigitDetermines whether a specified character is a valid hexadecimal digit.
Public methodStatic memberSupported by the XNA FrameworkIsHexEncodingDetermines whether a character in a string is hexadecimal encoded.
Protected methodSupported by the XNA FrameworkIsReservedCharacterInfrastructure. Obsolete. Gets whether the specified character is a reserved character.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsWellFormedOriginalStringIndicates whether the string used to construct this Uri was well-formed and is not required to be further escaped.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsWellFormedUriStringIndicates whether the string is well-formed by attempting to construct a URI with the string and ensures that the string does not require further escaping.
Public methodSupported by the XNA FrameworkMakeRelative Obsolete. Determines the difference between two Uri instances.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsMakeRelativeUriDetermines the difference between two Uri instances.
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkParseInfrastructure. Obsolete. Parses the URI of the current instance to ensure it contains all the parts required for a valid URI.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsToStringGets a canonical string representation for the specified Uri instance. (Overrides Object::ToString().)
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsTryCreate(String, UriKind, Uri%)Creates a new Uri using the specified String instance and a UriKind.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsTryCreate(Uri, String, Uri%)Creates a new Uri using the specified base and relative String instances.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsTryCreate(Uri, Uri, Uri%)Creates a new Uri using the specified base and relative Uri instances.
Protected methodSupported by the XNA FrameworkUnescapeInfrastructure. Obsolete. Converts the specified string by replacing any escape sequences with their unescaped representation.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsUnescapeDataStringConverts a string to its unescaped representation.
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  NameDescription
Public operatorStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEqualityDetermines whether two Uri instances have the same value.
Public operatorStatic memberSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsInequalityDetermines whether two Uri instances do not have the same value.
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  NameDescription
Public fieldStatic memberSupported by the XNA FrameworkSchemeDelimiterSpecifies the characters that separate the communication protocol scheme from the address portion of the URI. This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeFileSpecifies that the URI is a pointer to a file. This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeFtpSpecifies that the URI is accessed through the File Transfer Protocol (FTP). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeGopherSpecifies that the URI is accessed through the Gopher protocol. This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeHttpSpecifies that the URI is accessed through the Hypertext Transfer Protocol (HTTP). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeHttpsSpecifies that the URI is accessed through the Secure Hypertext Transfer Protocol (HTTPS). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeMailtoSpecifies that the URI is an e-mail address and is accessed through the Simple Mail Transport Protocol (SMTP). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeNetPipeSpecifies that the URI is accessed through the NetPipe scheme used by Windows Communication Foundation (WCF). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeNetTcpSpecifies that the URI is accessed through the NetTcp scheme used by Windows Communication Foundation (WCF). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeNewsSpecifies that the URI is an Internet news group and is accessed through the Network News Transport Protocol (NNTP). This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkUriSchemeNntpSpecifies that the URI is an Internet news group and is accessed through the Network News Transport Protocol (NNTP). This field is read-only.
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  NameDescription
Explicit interface implemetationPrivate methodISerializable::GetObjectDataReturns the data needed to serialize the current instance.
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A URI is a compact representation of a resource available to your application on the intranet or Internet. The Uri class defines the properties and methods for handling URIs, including parsing, comparing, and combining. The Uri class properties are read-only; to create a modifiable object, use the UriBuilder class.

Relative URIs (for example, "/new/index.htm") must be expanded with respect to a base URI so that they are absolute. The MakeRelative method is provided to convert absolute URIs to relative URIs when necessary.

The Uri constructors do not escape URI strings if the string is a well-formed URI including a scheme identifier.

The Uri properties return a canonical data representation in escaped encoding, with all characters with Unicode values greater than 127 replaced with their hexadecimal equivalents. To put the URI in canonical form, the Uri constructor performs the following steps:

  • Converts the URI scheme to lowercase.

  • Converts the host name to lowercase.

  • If the host name is an IPv6 address, the canonical IPv6 address is used. ScopeId and other optional IPv6 data are removed.

  • Removes default and empty port numbers.

  • Canonicalizes the path for hierarchical URIs by compacting sequences such as /./, /../, //, including escaped representations. Note that there are some schemes for which escaped representations are not compacted.

  • For hierarchical URIs, if the host is not terminated with a forward slash (/), one is added.

  • By default, any reserved characters in the URI are escaped in accordance with RFC 2396. This behavior changes if International Resource Identifiers or International Domain Name parsing is enabled in which case reserved characters in the URI are escaped in accordance with RFC 3986 and RFC 3987.

As part of canonicalization in the constructor for some schemes, escaped representations are compacted. The schemes for which URI will compact escaped sequences include the following: file, http, https, net.pipe, and net.tcp. For all other schemes, escaped sequences are not compacted. For example: if you percent encode the two dots ".." as "%2E%2E" then the URI constructor will compact this sequence for some schemes. For example, the following code sample shows a URI constructor for the http scheme.

    Uri uri = new Uri("http://myUrl/%2E%2E/%2E%2E");
    Console.WriteLine(uri.AbsoluteUri);
    Console.WriteLine(uri.PathAndQuery);

When this code is executed, it returns the following output with the escaped sequence compacted.

http://myUrl/
/

The following code example shows a URI constructor for the ftp scheme:

    Uri uri = new Uri("ftp://myUrl/%2E%2E/%2E%2E");
    Console.WriteLine(uri.AbsoluteUri);
    Console.WriteLine(uri.PathAndQuery);

When this code is executed, it returns the following output with the escaped sequence not compacted.

ftp://myUrl/%2E%2E/%2E%2E
/%2E%2E/%2E%2E

You can transform the contents of the Uri class from an escape encoded URI reference to a readable URI reference by using the ToString method. Note that some reserved characters might still be escaped in the output of the ToString method. This is to support unambiguous reconstruction of a URI from the value returned by ToString.

Some URIs include a fragment identifier or a query or both. A fragment identifier is any text that follows a number sign (#), not including the number sign; the fragment text is stored in the Fragment property. Query information is any text that follows a question mark (?) in the URI; the query text is stored in the Query property.

In the .NET Framework version 1.1, if the string specified to a constructor contains an unknown scheme and "c:\", the Uri class inserts "//" after the colon. For example, the URI xyz:c:\abc is converted to xyz://c:/abc. In the .NET Framework version 2.0, this behavior has been removed, and the example string is converted to xyz:c:/abc.

NoteNote

The URI class supports the use of IP addresses in both quad-notation for IPv4 protocol and colon-hexadecimal for IPv6 protocol. Remember to enclose the IPv6 address in square brackets, as in http://[::1].

International Resource Identifier Support

Web addresses are typically expressed using uniform resource identifiers that consist of a very restricted set of characters:

  • Upper and lower case ASCII letters from the English alphabet.

  • Digits from 0 to 9.

  • A small number of other ASCII symbols.

The specifications for URIs are documented in RFC 2396, RFC 2732, RFC 3986, and RFC 3987 published by the Internet Engineering Task Force (IETF).

With the growth of the Internet, there is a growing need to identify resources using languages other than English. Identifiers which facilitate this need and allow non-ASCII characters (characters in the Unicode/ISO 10646 character set) are known as International Resource Identifiers (IRIs). The specifications for IRIs are documented in RFC 3987 published by IETF. Using IRIs allows a URL to contain Unicode characters.

The existing Uri class has been extended in .NET Framework v3.5, 3.0 SP1, and 2.0 SP1 to provide IRI support based on RFC 3987. Current users will not see any change from the .NET Framework 2.0 behavior unless they specifically enable IRI. This ensures application compatibility with prior versions of the .NET Framework.

To enable support for IRI, the following change is required:

  • Specify whether you want Internationalized Domain Name (IDN) parsing applied to the domain name and whether IRI parsing rules should be applied. This can be done in the machine.config or in the app.config file. For example, add the following:

    <configuration>
      <uri>
      <idn enabled="All" />
      <iriParsing enabled="true" />
      </uri>
    </configuration>
    

Enabling IDN will convert all Unicode labels in a domain name to their Punycode equivalents. Punycode names contain only ASCII characters and always start with the xn-- prefix. The reason for this is to support existing DNS servers on the Internet, since most DNS servers only support ASCII characters (see RFC 3940).

Enabling IRI and IDN affects the value of the Uri::DnsSafeHost property. Enabling IRI and IDN can also change the behavior of the Equals, OriginalString, GetComponents, and IsWellFormedOriginalString methods.

There are three possible values for IDN depending on the DNS servers that are used:

  • idn enabled = All

    This value will convert any Unicode domain names to their Punycode equivalents (IDN names).

  • idn enabled = AllExceptIntranet

    This value will convert all Unicode domain names not on the local Intranet to use the Punycode equivalents (IDN names). In this case to handle international names on the local Intranet, the DNS servers that are used for the Intranet should support Unicode name resolution.

  • idn enabled = None

    This value will not convert any Unicode domain names to use Punycode. This is the default value which is consistent with the .NET Framework 2.0 behaviour.

Enabling IRI parsing (iriParsing enabled = true) will do normalization and character checking according to the latest IRI rules in RFC 3986 and RFC 3987. The default value is false and will do normalization and character checking according to RFC 2396 and RFC 2732 (for IPv6 literals).

IRI and IDN processing in the Uri class can also be controlled using the System.Configuration::IriParsingElement, System.Configuration::IdnElement, and System.Configuration::UriSection configuration setting classes. The System.Configuration::IriParsingElement setting enables or disables IRI processing in the Uri class. The System.Configuration::IdnElement setting enables or disables IDN processing in the Uri class. The System.Configuration::IriParsingElement setting also indirectly controls IDN. IRI processing must be enabled for IDN processing to be possible. If IRI processing is disabled, then IDN processing will be set to the default setting where the .NET Framework 2.0 behavior is used for compatibility and IDN names are not used.

The configuration setting for the System.Configuration::IriParsingElement and System.Configuration::IdnElement will be read once when the first System::Uri class is constructed. Changes to configuration settings after that time are ignored.

The System::GenericUriParser class has also been extended to allow creating a customizable parser that supports IRI and IDN. The behavior of a System::GenericUriParser object is specified by passing a bitwise combination of the values available in the System::GenericUriParserOptions enumeration to the System::GenericUriParser constructor. The GenericUriParserOptions::IriParsing type indicates the parser supports the parsing rules specified in RFC 3987 for International Resource Identifiers (IRI). Whether IRI is used is dictated by the configuration values previously discussed.

The GenericUriParserOptions::Idn type indicates the parser supports Internationalized Domain Name (IDN) parsing (IDN) of host names. Whether IDN is used is dictated by the configuration values previously discussed.

Performance Considerations

If you use a Web.config file that contains URIs to initialize your application, additional time is required to process the URIs if their scheme identifiers are nonstandard. In such a case, initialize the affected parts of your application when the URIs are needed, not at start time.

Notes to Callers

Because of security concerns, your application should use caution when accepting Uri instances from untrusted sources and with dontEscape set to true.You can check a URI string for validity by calling the IsWellFormedOriginalString method.

The following example creates an instance of the Uri class and uses it to create a WebRequest instance.

Uri^ siteUri = gcnew Uri( "http://www.contoso.com/" );
WebRequest^ wr = WebRequest::Create( siteUri );

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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