| java.lang.Object
 java.net.URL
| URL | | final public class URL implements java.io.Serializable(Code) | | 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:
http://archive.ncsa.uiuc.edu/SDG/Software/Mosaic/Demo/url-primer.html
In general, a URL can be broken into several parts. The previous
example of a URL indicates that the protocol to use is
http (HyperText Transfer Protocol) and that the
information resides on a host machine named
www.ncsa.uiuc.edu. The information on that host
machine is named /SDG/Software/Mosaic/Demo/url-primer.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://archive.ncsa.uiuc.edu:80/SDG/Software/Mosaic/Demo/url-primer.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.
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.
author:
James Gosling
version:
1.108, 10/10/06
since:
JDK1.0 |
| Constructor Summary | |
| public | URL(String protocol, String host, int port, String file)
Creates a URL object from the specified
protocol, host, port
number, and file.
host can be expressed as a host name or a literal
IP address. | | public | URL(String protocol, String host, String file)
Creates a URL from the specified protocol
name, host name, and file name. | | public | URL(String protocol, String host, int port, String file, URLStreamHandler handler)
Creates a URL object from the specified
protocol, host, port
number, file, and handler. | | public | URL(String spec)
Creates a URL object from the String
representation. | | public | URL(URL context, String spec)
Creates a URL by parsing the given spec within a specified context.
The new URL is created from the given context URL and the spec
argument as described in
RFC2396 "Uniform Resource Identifiers : Generic * Syntax" :
<scheme>://<authority><path>?<query>#<fragment>
The reference is parsed into the scheme, authority, path, query and
fragment parts. | | public | URL(URL context, String spec, URLStreamHandler handler)
Creates a URL by parsing the given spec with the specified handler
within a specified context. |
| Method Summary | |
| public boolean | equals(Object 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. | | public String | getAuthority()
Gets the authority part of this URL. | | final public Object | getContent()
Gets the contents of this URL. | | final public Object | getContent(Class[] classes)
Gets the contents of this URL. | | public int | getDefaultPort()
Gets the default port number of the protocol associated
with this URL. | | public String | getFile()
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. | | public String | getHost()
Gets the host name of this URL, if applicable.
The format of the host conforms to RFC 2732, i.e. | | public String | getPath()
Gets the path part of this URL. | | public int | getPort()
Gets the port number of this URL. | | public String | getProtocol()
Gets the protocol name of this URL. | | public String | getQuery()
Gets the query part of this URL. | | public String | getRef()
Gets the anchor (also known as the "reference") of this
URL. | | static URLStreamHandler | getURLStreamHandler(String protocol)
Returns the Stream Handler. | | public String | getUserInfo()
Gets the userInfo part of this URL. | | public synchronized int | hashCode()
Creates an integer suitable for hash table indexing.
The hash code is based upon all the URL components relevant for URL
comparison. | | public URLConnection | openConnection()
Returns a URLConnection object that represents a
connection to the remote object referred to by the URL.
A new connection is opened every time by calling the
openConnection method of the protocol handler for
this URL.
If for the URL's protocol (such as HTTP or JAR), there
exists a public, specialized URLConnection subclass belonging
to one of the following packages or one of their subpackages:
java.lang, java.io, java.util, java.net, the connection
returned will be of that subclass. | | final public InputStream | openStream()
Opens a connection to this URL and returns an
InputStream for reading from that connection. | | public boolean | sameFile(URL 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.
Parameters:
other - the URL to compare against. | | protected void | set(String protocol, String host, int port, String file, String ref)
Sets the fields of the URL. | | protected void | set(String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)
Sets the specified 8 fields of the URL. | | public static void | setURLStreamHandlerFactory(URLStreamHandlerFactory fac)
Sets an application's URLStreamHandlerFactory. | | public String | toExternalForm()
Constructs a string representation of this URL. | | public String | toString()
Constructs a string representation of this URL. |
| hostAddress | | transient InetAddress hostAddress(Code) | | The host's IP address, used in equals and hashCode.
Computed on demand. An uninitialized or unknown hostAddress is null.
|
| serialVersionUID | | final static long serialVersionUID(Code) | | |
| URL | | public URL(String protocol, String host, int port, String file) throws MalformedURLException(Code) | | Creates a URL object from the specified
protocol, host, port
number, and file.
host can be expressed as a host name or a literal
IP address. If IPv6 literal address is used, it should be
enclosed in square brackets ('[' and ']'), as
specified by RFC 2732;
However, the literal IPv6 address format defined in RFC 2373: IP
Version 6 Addressing Architecture is also accepted.
Specifying a port number of -1
indicates that the URL should use the default port for the
protocol.
If this is the first URL object being created with the specified
protocol, a stream protocol handler object, an instance of
class URLStreamHandler, is created for that protocol:
- If the application has previously set up an instance of
URLStreamHandlerFactory as the stream handler factory,
then the createURLStreamHandler method of that instance
is called with the protocol string as an argument to create the
stream protocol handler.
- If no
URLStreamHandlerFactory has yet been set up,
or if the factory's createURLStreamHandler method
returns null, then the constructor finds the
value of the system property:
java.protocol.handler.pkgs
If the value of that system property is not null,
it is interpreted as a list of packages separated by a vertical
slash character '|'. The constructor tries to load
the class named:
<package>.<protocol>.Handler
where <package> is replaced by the name of the package
and <protocol> is replaced by the name of the protocol.
If this class does not exist, or if the class exists but it is not
a subclass of URLStreamHandler, then the next package
in the list is tried.
- If the previous step fails to find a protocol handler, then the
constructor tries to load from a system default package.
<system default package>.<protocol>.Handler
If this class does not exist, or if the class exists but it is not a
subclass of URLStreamHandler, then a
MalformedURLException is thrown.
No validation of the inputs is performed by this constructor.
Parameters:
protocol - the name of the protocol to use.
Parameters:
host - the name of the host.
Parameters:
port - the port number on the host.
Parameters:
file - the file on the host
exception:
MalformedURLException - if an unknown protocol is specified.
See Also: java.lang.System.getProperty(java.lang.String)
See Also: java.net.URL.setURLStreamHandlerFactory(java.net.URLStreamHandlerFactory)
See Also: java.net.URLStreamHandler
See Also: java.net.URLStreamHandlerFactory.createURLStreamHandler(java.lang.String) |
| URL | | public URL(String protocol, String host, String file) throws MalformedURLException(Code) | | Creates a URL from the specified protocol
name, host name, and file name. The
default port for the specified protocol is used.
This method is equivalent to calling the four-argument
constructor with the arguments being protocol,
host, -1, and file.
No validation of the inputs is performed by this constructor.
Parameters:
protocol - the name of the protocol to use.
Parameters:
host - the name of the host.
Parameters:
file - the file on the host.
exception:
MalformedURLException - if an unknown protocol is specified.
See Also: java.net.URL.URL(java.lang.Stringjava.lang.Stringintjava.lang.String) |
| URL | | public URL(String protocol, String host, int port, String file, URLStreamHandler handler) throws MalformedURLException(Code) | | 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.
Parameters:
protocol - the name of the protocol to use.
Parameters:
host - the name of the host.
Parameters:
port - the port number on the host.
Parameters:
file - the file on the host
Parameters:
handler - the stream handler for the URL.
exception:
MalformedURLException - if an unknown protocol is specified.
exception:
SecurityException - if a security manager exists and itscheckPermission method doesn't allowspecifying a stream handler explicitly.
See Also: java.lang.System.getProperty(java.lang.String)
See Also: java.net.URL.setURLStreamHandlerFactory(java.net.URLStreamHandlerFactory)
See Also: java.net.URLStreamHandler
See Also: java.net.URLStreamHandlerFactory.createURLStreamHandler(java.lang.String)
See Also: SecurityManager.checkPermission
See Also: java.net.NetPermission |
| URL | | public URL(URL context, String spec) throws MalformedURLException(Code) | | Creates a URL by parsing the given spec within a specified context.
The new URL is created from the given context URL and the spec
argument as described in
RFC2396 "Uniform Resource Identifiers : Generic * Syntax" :
<scheme>://<authority><path>?<query>#<fragment>
The reference is parsed into the scheme, authority, path, query and
fragment parts. If the path component is empty and the scheme,
authority, and query components are undefined, then the new URL is a
reference to the current document. Otherwise, the fragment and query
parts present in the spec are used in the new URL.
If the scheme component is defined in the given spec and does not match
the scheme of the context, then the new URL is created as an absolute
URL based on the spec alone. Otherwise the scheme component is inherited
from the context URL.
If the authority component is present in the spec then the spec is
treated as absolute and the spec authority and path will replace the
context authority and path. If the authority component is absent in the
spec then the authority of the new URL will be inherited from the
context.
If the spec's path component begins with a slash character
"/" then the
path is treated as absolute and the spec path replaces the context path.
Otherwise, the path is treated as a relative path and is appended to the
context path, as described in RFC2396. Also, in this case,
the path is canonicalized through the removal of directory
changes made by occurences of ".." and ".".
For a more detailed description of URL parsing, refer to RFC2396.
Parameters:
context - the context in which to parse the specification.
Parameters:
spec - the String to parse as a URL.
exception:
MalformedURLException - if no protocol is specified, or anunknown protocol is found.
See Also: java.net.URL.URL(java.lang.Stringjava.lang.Stringintjava.lang.String)
See Also: java.net.URLStreamHandler
See Also: java.net.URLStreamHandler.parseURL(java.net.URLjava.lang.Stringintint) |
| equals | | public boolean equals(Object obj)(Code) | | 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.
Parameters:
obj - the URL to compare against. true if the objects are the same;false otherwise. |
| getAuthority | | public String getAuthority()(Code) | | Gets the authority part of this URL.
the authority part of this URL
since:
1.3 |
| getContent | | final public Object getContent(Class[] classes) throws java.io.IOException(Code) | | Gets the contents of this URL. This method is a shorthand for:
openConnection().getContent(Class[])
Parameters:
classes - an array of Java types the content object of this URL that is the first match ofthe types specified in the classes array.null if none of the requested types are supported.
exception:
IOException - if an I/O exception occurs.
See Also: java.net.URLConnection.getContent(Class[])
since:
1.3 |
| getDefaultPort | | public int getDefaultPort()(Code) | | 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.
the port number |
| getFile | | public String getFile()(Code) | | 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.
the file name of this URL,or an empty string if one does not exist |
| getHost | | public String getHost()(Code) | | 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 ']').
the host name of this URL. |
| getPath | | public String getPath()(Code) | | Gets the path part of this URL.
the path part of this URL, or anempty string if one does not exist
since:
1.3 |
| getPort | | public int getPort()(Code) | | Gets the port number of this URL.
the port number, or -1 if the port is not set |
| getProtocol | | public String getProtocol()(Code) | | Gets the protocol name of this URL.
the protocol of this URL. |
| getQuery | | public String getQuery()(Code) | | Gets the query part of this URL.
the query part of this URL, or null if one does not exist
since:
1.3 |
| getRef | | public String getRef()(Code) | | Gets the anchor (also known as the "reference") of this
URL.
the anchor (also known as the "reference") of thisURL, or null if one does not exist |
| getURLStreamHandler | | static URLStreamHandler getURLStreamHandler(String protocol)(Code) | | Returns the Stream Handler.
Parameters:
protocol - the protocol to use |
| getUserInfo | | public String getUserInfo()(Code) | | Gets the userInfo part of this URL.
the userInfo part of this URL, or null if one does not exist |
| hashCode | | public synchronized int hashCode()(Code) | | 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.
a hash code for this URL. |
| openConnection | | public URLConnection openConnection() throws java.io.IOException(Code) | | Returns a URLConnection object that represents a
connection to the remote object referred to by the URL.
A new connection is opened every time by calling the
openConnection method of the protocol handler for
this URL.
If for the URL's protocol (such as HTTP or JAR), there
exists a public, specialized URLConnection subclass belonging
to one of the following packages or one of their subpackages:
java.lang, java.io, java.util, java.net, the connection
returned will be of that subclass. For example, for HTTP an
HttpURLConnection will be returned, and for JAR a
JarURLConnection will be returned.
NOTE: java.net.HttpURLConnection is found in J2ME CDC profiles
such as J2ME Foundation Profile.
Subclasses of these should
a URLConnection to the URL.
exception:
IOException - if an I/O exception occurs.
See Also: java.net.URL.URL(java.lang.Stringjava.lang.Stringintjava.lang.String)
See Also: java.net.URLConnection
See Also: java.net.URLStreamHandler.openConnection(java.net.URL) |
| sameFile | | public boolean sameFile(URL other)(Code) | | 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.
Parameters:
other - the URL to compare against. true if they reference the same remote object;false otherwise. |
| set | | protected void set(String protocol, String host, int port, String file, String ref)(Code) | | Sets the fields of the URL. This is not a public method so that
only URLStreamHandlers can modify URL fields. URLs are
otherwise constant.
Parameters:
protocol - the name of the protocol to use
Parameters:
host - the name of the host
Parameters:
port - the port number on the host
Parameters:
file - the file on the host
Parameters:
ref - the internal reference in the URL |
| set | | protected void set(String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)(Code) | | Sets the specified 8 fields of the URL. This is not a public method so
that only URLStreamHandlers can modify URL fields. URLs are otherwise
constant.
Parameters:
protocol - the name of the protocol to use
Parameters:
host - the name of the host
Parameters:
port - the port number on the host
Parameters:
authority - the authority part for the url
Parameters:
userInfo - the username and password
Parameters:
path - the file on the host
Parameters:
ref - the internal reference in the URL
Parameters:
query - the query part of this URL
since:
1.3 |
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