jdk.net.URL — clojure-interop/java.net 1.0.5

Class URL represents a Uniform Resource Locator, a pointer to a "resource" on the World Wide Web. A resource can be something as simple as a file or a directory, or it can be a reference to a more complicated object, such as a query to a database or to a search engine. More information on the types of URLs and their formats can be found at:

Types of URL

In general, a URL can be broken into several parts. Consider the following example:

http://www.example.com/docs/resource1.html

The URL above indicates that the protocol to use is http (HyperText Transfer Protocol) and that the information resides on a host machine named www.example.com. The information on that host machine is named /docs/resource1.html. The exact meaning of this name on the host machine is both protocol dependent and host dependent. The information normally resides in a file, but it could be generated on the fly. This component of the URL is called the path component.

A URL can optionally specify a "port", which is the port number to which the TCP connection is made on the remote host machine. If the port is not specified, the default port for the protocol is used instead. For example, the default port for http is 80. An alternative port could be specified as:

http://www.example.com:1080/docs/resource1.html

The syntax of URL is defined by RFC 2396: Uniform Resource Identifiers (URI): Generic Syntax, amended by RFC 2732: Format for Literal IPv6 Addresses in URLs. The Literal IPv6 address format also supports scope_ids. The syntax and usage of scope_ids is described here.

A URL may have appended to it a "fragment", also known as a "ref" or a "reference". The fragment is indicated by the sharp sign character "#" followed by more characters. For example,

http://java.sun.com/index.html#chapter1

This fragment is not technically part of the URL. Rather, it indicates that after the specified resource is retrieved, the application is specifically interested in that part of the document that has the tag chapter1 attached to it. The meaning of a tag is resource specific.

An application can also specify a "relative URL", which contains only enough information to reach the resource relative to another URL. Relative URLs are frequently used within HTML pages. For example, if the contents of the URL:

http://java.sun.com/index.html

contained within it the relative URL:

FAQ.html

it would be a shorthand for:

http://java.sun.com/FAQ.html

The relative URL need not specify all the components of a URL. If the protocol, host name, or port number is missing, the value is inherited from the fully specified URL. The file component must be specified. The optional fragment is not inherited.

The URL class does not itself encode or decode any URL components according to the escaping mechanism defined in RFC2396. It is the responsibility of the caller to encode any fields, which need to be escaped prior to calling URL, and also to decode any escaped fields, that are returned from URL. Furthermore, because URL has no knowledge of URL escaping, it does not recognise equivalence between the encoded or decoded form of the same URL. For example, the two URLs:

http://foo.com/hello world/ and http://foo.com/hello%20world would be considered not equal to each other.

Note, the URI class does perform escaping of its component fields in certain circumstances. The recommended way to manage the encoding and decoding of URLs is to use URI, and to convert between these two classes using toURI() and URI.toURL().

The URLEncoder and URLDecoder classes can also be used, but only for HTML form encoding, which is not the same as the encoding scheme defined in RFC2396.

*set-url-stream-handler-factory clj

(*set-url-stream-handler-factory fac)

Sets an application's URLStreamHandlerFactory. This method can be called at most once in a given Java Virtual Machine.

The URLStreamHandlerFactory instance is used to construct a stream protocol handler from a protocol name.

If there is a security manager, this method first calls the security manager's checkSetFactory method to ensure the operation is allowed. This could result in a SecurityException.

fac - the desired factory. - java.net.URLStreamHandlerFactory

throws: java.lang.Error - if the application has already set a factory.

->url clj

(->url spec)

(->url context spec)

(->url protocol host file)

(->url protocol host port file)

(->url protocol host port file handler)

Constructor.

Creates a URL object from the specified protocol, host, port number, file, and handler. Specifying a port number of -1 indicates that the URL should use the default port for the protocol. Specifying a handler of null indicates that the URL should use a default stream handler for the protocol, as outlined for: java.net.URL#URL(java.lang.String, java.lang.String, int, java.lang.String)

If the handler is not null and there is a security manager, the security manager's checkPermission method is called with a NetPermission("specifyStreamHandler") permission. This may result in a SecurityException.

No validation of the inputs is performed by this constructor.

protocol - the name of the protocol to use. - java.lang.String host - the name of the host. - java.lang.String port - the port number on the host. - int file - the file on the host - java.lang.String handler - the stream handler for the URL. - java.net.URLStreamHandler

throws: java.net.MalformedURLException - if an unknown protocol is specified.

equals clj

(equals this obj)

Compares this URL for equality with another object.

If the given object is not a URL then this method immediately returns false.

Two URL objects are equal if they have the same protocol, reference equivalent hosts, have the same port number on the host, and the same file and fragment of the file.

Two hosts are considered equivalent if both host names can be resolved into the same IP addresses; else if either host name can't be resolved, the host names must be equal without regard to case; or both host names equal to null.

Since hosts comparison requires name resolution, this operation is a blocking operation.

Note: The defined behavior for equals is known to be inconsistent with virtual hosting in HTTP.

obj - the URL to compare against. - java.lang.Object

returns: true if the objects are the same; false otherwise. - boolean

get-authority clj

(get-authority this)

Gets the authority part of this URL.

returns: the authority part of this URL - java.lang.String

get-content clj

(get-content this)

(get-content this classes)

Gets the contents of this URL. This method is a shorthand for:

 openConnection().getContent(Class[])

classes - an array of Java types - java.lang.Class[]

returns: the content object of this URL that is the first match of the types specified in the classes array. null if none of the requested types are supported. - java.lang.Object

throws: java.io.IOException - if an I/O exception occurs.

get-default-port clj

(get-default-port this)

Gets the default port number of the protocol associated with this URL. If the URL scheme or the URLStreamHandler for the URL do not define a default port number, then -1 is returned.

returns: the port number - int

get-file clj

(get-file this)

Gets the file name of this URL. The returned file portion will be the same as getPath(), plus the concatenation of the value of getQuery(), if any. If there is no query portion, this method and getPath() will return identical results.

returns: the file name of this URL, or an empty string if one does not exist - java.lang.String

get-host clj

(get-host this)

Gets the host name of this URL, if applicable. The format of the host conforms to RFC 2732, i.e. for a literal IPv6 address, this method will return the IPv6 address enclosed in square brackets ('[' and ']').

returns: the host name of this URL. - java.lang.String

get-path clj

(get-path this)

Gets the path part of this URL.

returns: the path part of this URL, or an empty string if one does not exist - java.lang.String

get-port clj

(get-port this)

Gets the port number of this URL.

returns: the port number, or -1 if the port is not set - int

get-protocol clj

(get-protocol this)

Gets the protocol name of this URL.

returns: the protocol of this URL. - java.lang.String

get-query clj

(get-query this)

Gets the query part of this URL.

returns: the query part of this URL, or null if one does not exist - java.lang.String

get-ref clj

(get-ref this)

Gets the anchor (also known as the "reference") of this URL.

returns: the anchor (also known as the "reference") of this URL, or null if one does not exist - java.lang.String

get-user-info clj

(get-user-info this)

Gets the userInfo part of this URL.

returns: the userInfo part of this URL, or null if one does not exist - java.lang.String

hash-code clj

(hash-code this)

Creates an integer suitable for hash table indexing.

The hash code is based upon all the URL components relevant for URL comparison. As such, this operation is a blocking operation.

returns: a hash code for this URL. - int

open-connection clj

(open-connection this)

(open-connection this proxy)

Same as openConnection(), except that the connection will be made through the specified proxy; Protocol handlers that do not support proxing will ignore the proxy parameter and make a normal connection.

Invoking this method preempts the system's default ProxySelector settings.

proxy - the Proxy through which this connection will be made. If direct connection is desired, Proxy.NO_PROXY should be specified. - java.net.Proxy

returns: a URLConnection to the URL. - java.net.URLConnection

throws: java.io.IOException - if an I/O exception occurs.

open-stream clj

(open-stream this)

Opens a connection to this URL and returns an InputStream for reading from that connection. This method is a shorthand for:

 openConnection().getInputStream()

returns: an input stream for reading from the URL connection. - java.io.InputStream

throws: java.io.IOException - if an I/O exception occurs.

same-file clj

(same-file this other)

Compares two URLs, excluding the fragment component.

Returns true if this URL and the other argument are equal without taking the fragment component into consideration.

other - the URL to compare against. - java.net.URL

returns: true if they reference the same remote object; false otherwise. - boolean

to-external-form clj

(to-external-form this)

Constructs a string representation of this URL. The string is created by calling the toExternalForm method of the stream protocol handler for this object.

returns: a string representation of this object. - java.lang.String

to-string clj

(to-string this)

Constructs a string representation of this URL. The string is created by calling the toExternalForm method of the stream protocol handler for this object.

returns: a string representation of this object. - java.lang.String

to-uri clj

(to-uri this)

Returns a URI equivalent to this URL. This method functions in the same way as new URI (this.toString()). Note, any URL instance that complies with RFC 2396 can be converted to a URI. However, some URLs that are not strictly in compliance can not be converted to a URI.

returns: a URI instance equivalent to this URL. - java.net.URI

throws: java.net.URISyntaxException - if this URL is not formatted strictly according to to RFC2396 and cannot be converted to a URI.