Uri Class

Definition

public ref class Uri

public ref class Uri : IEquatable<Uri ^>, ISpanFormattable, System::Runtime::Serialization::ISerializable

public ref class Uri : System::Runtime::Serialization::ISerializable

public ref class Uri : ISpanFormattable, System::Runtime::Serialization::ISerializable

public ref class Uri : MarshalByRefObject, System::Runtime::Serialization::ISerializable

public class Uri

public class Uri : IEquatable<Uri>, ISpanFormattable, System.Runtime.Serialization.ISerializable

public class Uri : System.Runtime.Serialization.ISerializable

public class Uri : ISpanFormattable, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class Uri : MarshalByRefObject, System.Runtime.Serialization.ISerializable

[System.Serializable]
[System.ComponentModel.TypeConverter(typeof(System.UriTypeConverter))]
public class Uri : System.Runtime.Serialization.ISerializable

type Uri = class

type Uri = class
    interface IEquatable<Uri>
    interface IFormattable
    interface ISpanFormattable
    interface ISerializable

type Uri = class
    interface ISerializable

type Uri = class
    interface ISpanFormattable
    interface IFormattable
    interface ISerializable

type Uri = class
    interface IFormattable
    interface ISpanFormattable
    interface IEquatable<Uri>
    interface ISerializable

[<System.Serializable>]
type Uri = class
    inherit MarshalByRefObject
    interface ISerializable

[<System.Serializable>]
[<System.ComponentModel.TypeConverter(typeof(System.UriTypeConverter))>]
type Uri = class
    interface ISerializable

Public Class Uri

Public Class Uri
Implements IEquatable(Of Uri), ISerializable, ISpanFormattable

Public Class Uri
Implements ISerializable

Public Class Uri
Implements ISerializable, ISpanFormattable

Public Class Uri
Inherits MarshalByRefObject
Implements ISerializable

Inheritance

Object

Uri

Inheritance

Object

MarshalByRefObject

Uri

Attributes

SerializableAttribute TypeConverterAttribute

Implements

IEquatable<Uri> IFormattable ISpanFormattable ISerializable

Examples

The following example creates an instance of the Uri class and uses it to perform a GET request with HttpClient.

Uri siteUri = new Uri("http://www.contoso.com/");

// HttpClient lifecycle management best practices:
// https://learn.microsoft.com/dotnet/fundamentals/networking/http/httpclient-guidelines#recommended-use
HttpClient client = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, siteUri);
HttpResponseMessage response = client.Send(request);

let siteUri = Uri "http://www.contoso.com/"

// HttpClient lifecycle management best practices:
// https://learn.microsoft.com/dotnet/fundamentals/networking/http/httpclient-guidelines#recommended-use
use client = new HttpClient ()
use request = new HttpRequestMessage (HttpMethod.Get, siteUri)
use response = client.Send request

Dim siteUri As New Uri("http://www.contoso.com/")

' HttpClient lifecycle management best practices:
' https://learn.microsoft.com/dotnet/fundamentals/networking/http/httpclient-guidelines#recommended-use
Dim client As New HttpClient()
Dim request As New HttpRequestMessage(HttpMethod.Get, siteUri)
Dim response As HttpResponseMessage = client.Send(request)

The following code snippet shows example values of the various properties on the class.

Uri uri = new Uri("https://user:password@www.contoso.com:80/Home/Index.htm?q1=v1&q2=v2#FragmentName");

Console.WriteLine($"AbsolutePath: {uri.AbsolutePath}");
Console.WriteLine($"AbsoluteUri: {uri.AbsoluteUri}");
Console.WriteLine($"DnsSafeHost: {uri.DnsSafeHost}");
Console.WriteLine($"Fragment: {uri.Fragment}");
Console.WriteLine($"Host: {uri.Host}");
Console.WriteLine($"HostNameType: {uri.HostNameType}");
Console.WriteLine($"IdnHost: {uri.IdnHost}");
Console.WriteLine($"IsAbsoluteUri: {uri.IsAbsoluteUri}");
Console.WriteLine($"IsDefaultPort: {uri.IsDefaultPort}");
Console.WriteLine($"IsFile: {uri.IsFile}");
Console.WriteLine($"IsLoopback: {uri.IsLoopback}");
Console.WriteLine($"IsUnc: {uri.IsUnc}");
Console.WriteLine($"LocalPath: {uri.LocalPath}");
Console.WriteLine($"OriginalString: {uri.OriginalString}");
Console.WriteLine($"PathAndQuery: {uri.PathAndQuery}");
Console.WriteLine($"Port: {uri.Port}");
Console.WriteLine($"Query: {uri.Query}");
Console.WriteLine($"Scheme: {uri.Scheme}");
Console.WriteLine($"Segments: {string.Join(", ", uri.Segments)}");
Console.WriteLine($"UserEscaped: {uri.UserEscaped}");
Console.WriteLine($"UserInfo: {uri.UserInfo}");

// AbsolutePath: /Home/Index.htm
// AbsoluteUri: https://user:password@www.contoso.com:80/Home/Index.htm?q1=v1&q2=v2#FragmentName
// DnsSafeHost: www.contoso.com
// Fragment: #FragmentName
// Host: www.contoso.com
// HostNameType: Dns
// IdnHost: www.contoso.com
// IsAbsoluteUri: True
// IsDefaultPort: False
// IsFile: False
// IsLoopback: False
// IsUnc: False
// LocalPath: /Home/Index.htm
// OriginalString: https://user:password@www.contoso.com:80/Home/Index.htm?q1=v1&q2=v2#FragmentName
// PathAndQuery: /Home/Index.htm?q1=v1&q2=v2
// Port: 80
// Query: ?q1=v1&q2=v2
// Scheme: https
// Segments: /, Home/, Index.htm
// UserEscaped: False
// UserInfo: user:password

let uri = Uri "https://user:password@www.contoso.com:80/Home/Index.htm?q1=v1&q2=v2#FragmentName"

printfn $"AbsolutePath: {uri.AbsolutePath}"
printfn $"AbsoluteUri: {uri.AbsoluteUri}"
printfn $"DnsSafeHost: {uri.DnsSafeHost}"
printfn $"Fragment: {uri.Fragment}"
printfn $"Host: {uri.Host}"
printfn $"HostNameType: {uri.HostNameType}"
printfn $"IdnHost: {uri.IdnHost}"
printfn $"IsAbsoluteUri: {uri.IsAbsoluteUri}"
printfn $"IsDefaultPort: {uri.IsDefaultPort}"
printfn $"IsFile: {uri.IsFile}"
printfn $"IsLoopback: {uri.IsLoopback}"
printfn $"IsUnc: {uri.IsUnc}"
printfn $"LocalPath: {uri.LocalPath}"
printfn $"OriginalString: {uri.OriginalString}"
printfn $"PathAndQuery: {uri.PathAndQuery}"
printfn $"Port: {uri.Port}"
printfn $"Query: {uri.Query}"
printfn $"Scheme: {uri.Scheme}"
printfn $"""Segments: {String.Join(", ", uri.Segments)}"""
printfn $"UserEscaped: {uri.UserEscaped}"
printfn $"UserInfo: {uri.UserInfo}"

// AbsolutePath: /Home/Index.htm
// AbsoluteUri: https://user:password@www.contoso.com:80/Home/Index.htm?q1=v1&q2=v2#FragmentName
// DnsSafeHost: www.contoso.com
// Fragment: #FragmentName
// Host: www.contoso.com
// HostNameType: Dns
// IdnHost: www.contoso.com
// IsAbsoluteUri: True
// IsDefaultPort: False
// IsFile: False
// IsLoopback: False
// IsUnc: False
// LocalPath: /Home/Index.htm
// OriginalString: https://user:password@www.contoso.com:80/Home/Index.htm?q1=v1&q2=v2#FragmentName
// PathAndQuery: /Home/Index.htm?q1=v1&q2=v2
// Port: 80
// Query: ?q1=v1&q2=v2
// Scheme: https
// Segments: /, Home/, Index.htm
// UserEscaped: False
// UserInfo: user:password

Remarks

A uniform resource identifier (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 MakeRelativeUri 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.
• Converts implicit file paths without the file:// scheme (for example, "C:\my\file") to explicit file paths with the file:// scheme.
• Escaped characters (also known as percent-encoded octets) that don't have a reserved purpose are decoded (also known as being unescaped). These unreserved characters include uppercase and lowercase letters (%41-%5A and %61-%7A), decimal digits (%30-%39), hyphen (%2D), period (%2E), underscore (%5F), and tilde (%7E).
• Canonicalizes the path for hierarchical URIs by compacting sequences such as /./ and /../ (whether or not the sequence is escaped). Note that there are some schemes for which these sequences 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, dot-segments (/./ and /../) are compacted (in other words, they're removed). The schemes for which Uri compacts segments include http, https, tcp, net.pipe, and net.tcp. For some other schemes, these sequences are not compacted. The following code snippet shows how compacting looks in practice. The escaped sequences are unescaped, if necessary, and then compacted.

var uri = new Uri("http://myUrl/../.."); // http scheme, unescaped
OR
var uri = new Uri("http://myUrl/%2E%2E/%2E%2E"); // http scheme, escaped
OR
var uri = new Uri("ftp://myUrl/../.."); // ftp scheme, unescaped
OR
var uri = new Uri("ftp://myUrl/%2E%2E/%2E%2E"); // ftp scheme, escaped

Console.WriteLine($"AbsoluteUri: {uri.AbsoluteUri}");
Console.WriteLine($"PathAndQuery: {uri.PathAndQuery}");

When this code executes, it returns output similar to the following text.

AbsoluteUri: http://myurl/
PathAndQuery: /

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.

International resource identifier support

Web addresses are typically expressed using URIs 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).

Identifiers that facilitate the need to identify resources using languages other than English 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. Normalization and character checking are done according to the latest IRI rules in RFC 3986 and RFC 3987.

IRI and IDN processing in the Uri class can 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 configuration setting for the System.Configuration.IriParsingElement and System.Configuration.IdnElement are 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).

The GenericUriParserOptions.Idn type indicates that the parser supports Internationalized Domain Name (IDN) parsing of host names. In .NET (Core) and .NET Framework 4.5+, IDN is always used. In previous versions, a configuration option determines whether IDN is used.

Implicit file path support

Uri can also be used to represent local file system paths. These paths can be represented explicitly in URIs that begin with the file:// scheme, and implicitly in URIs that do not have the file:// scheme. As a concrete example, the following two URIs are both valid, and represent the same file path:

Uri uri1 = new Uri("C:/test/path/file.txt") // Implicit file path.
Uri uri2 = new Uri("file:///C:/test/path/file.txt") // Explicit file path.

These implicit file paths are not compliant with the URI specification and should be avoided when possible. When using .NET Core on Unix-based systems, implicit file paths can be especially problematic, because an absolute implicit file path is indistinguishable from a relative path. When such ambiguity is present, Uri default to interpreting the path as an absolute URI.

Security considerations

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

When dealing with untrusted user input, confirm assumptions about the newly created Uri instance before trusting its properties. This can be done in the following way:

string userInput = ...;

Uri baseUri = new Uri("https://myWebsite/files/");

if (!Uri.TryCreate(baseUri, userInput, out Uri newUri))
{
    // Fail: invalid input.
}

if (!baseUri.IsBaseOf(newUri))
{
    // Fail: the Uri base has been modified - the created Uri is not rooted in the original directory.
}

This validation can be used in other cases, like when dealing with UNC paths, by simply changing the baseUri:

Uri baseUri = new Uri(@"\\host\share\some\directory\name\");

For more details about the design and security considerations of Uri and UriBuilder, review the following threat model documents:

• System.Uri threat model
• System.UriBuilder threat model

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.

Thread Safety

All members of Uri are thread-safe and may be used concurrently from multiple threads.

See also

• IdnElement
• IriParsingElement
• UriSection
• DnsSafeHost
• MakeRelative(Uri)
• IsWellFormedOriginalString()
• UriBuilder
• Changes to the System.Uri namespace in Version 2.0
• International Resource Identifier Support in System.UriSystem.Uri
• Network Programming in the .NET Framework