URLStreamHandler

public abstract class URLStreamHandler extends Object

The abstract class URLStreamHandler is the common superclass for all stream protocol handlers. A stream protocol handler knows how to make a connection for a particular protocol type, such as http, ftp, or gopher.

In most cases, an instance of a URLStreamHandler subclass is not created directly by an application. Rather, the first time a protocol name is encountered when constructing a URL, the appropriate stream protocol handler is automatically loaded.

Public Constructor Summary

Protected Method Summary

boolean
equals(URL u1, URL u2)
Provides the default equals calculation.
int
getDefaultPort()
Returns the default port for a URL parsed by this handler.
synchronized InetAddress
getHostAddress(URL u)
Get the IP address of our host.
int
hashCode(URL u)
Provides the default hash calculation.
boolean
hostsEqual(URL u1, URL u2)
Compares the host components of two URLs.
abstract URLConnection
openConnection(URL u)
Opens a connection to the object referenced by the URL argument.
URLConnection
openConnection(URL u, Proxy p)
Same as openConnection(URL), except that the connection will be made through the specified proxy; Protocol handlers that do not support proxying will ignore the proxy parameter and make a normal connection.
void
parseURL(URL u, String spec, int start, int limit)
Parses the string representation of a URL into a URL object.
boolean
sameFile(URL u1, URL u2)
Compare two urls to see whether they refer to the same file, i.e., having the same protocol, host, port, and path.
void
setURL(URL u, String protocol, String host, int port, String file, String ref)
This method was deprecated. Use setURL(URL, String, String, int, String, String, String, String);
void
setURL(URL u, String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)
Sets the fields of the URL argument to the indicated values.
String
toExternalForm(URL u)
Converts a URL of a specific protocol to a String.

Inherited Method Summary

Public Constructors

public URLStreamHandler ()

Protected Methods

protected boolean equals (URL u1, URL u2)

Provides the default equals calculation. May be overidden by handlers for other protocols that have different requirements for equals(). This method requires that none of its arguments is null. This is guaranteed by the fact that it is only called by java.net.URL class.

Parameters
u1 a URL object
u2 a URL object
Returns
  • true if the two urls are considered equal, ie. they refer to the same fragment in the same file.

protected int getDefaultPort ()

Returns the default port for a URL parsed by this handler. This method is meant to be overidden by handlers with default port numbers.

Returns
  • the default port for a URL parsed by this handler.

protected synchronized InetAddress getHostAddress (URL u)

Get the IP address of our host. An empty host field or a DNS failure will result in a null return.

Parameters
u a URL object
Returns
  • an InetAddress representing the host IP address.

protected int hashCode (URL u)

Provides the default hash calculation. May be overidden by handlers for other protocols that have different requirements for hashCode calculation.

Parameters
u a URL object
Returns
  • an int suitable for hash table indexing

protected boolean hostsEqual (URL u1, URL u2)

Compares the host components of two URLs.

Parameters
u1 the URL of the first host to compare
u2 the URL of the second host to compare
Returns
  • true if and only if they are equal, false otherwise.

protected abstract URLConnection openConnection (URL u)

Opens a connection to the object referenced by the URL argument. This method should be overridden by a subclass.

If for the handler'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.

Parameters
u the URL that this connects to.
Returns
  • a URLConnection object for the URL.
Throws
IOException if an I/O error occurs while opening the connection.

protected URLConnection openConnection (URL u, Proxy p)

Same as openConnection(URL), except that the connection will be made through the specified proxy; Protocol handlers that do not support proxying will ignore the proxy parameter and make a normal connection. Calling this method preempts the system's default ProxySelector settings.

Parameters
u the URL that this connects to.
p the proxy through which the connection will be made. If direct connection is desired, Proxy.NO_PROXY should be specified.
Returns
  • a URLConnection object for the URL.
Throws
IOException if an I/O error occurs while opening the connection.
IllegalArgumentException if either u or p is null, or p has the wrong type.
UnsupportedOperationException if the subclass that implements the protocol doesn't support this method.

protected void parseURL (URL u, String spec, int start, int limit)

Parses the string representation of a URL into a URL object.

If there is any inherited context, then it has already been copied into the URL argument.

The parseURL method of URLStreamHandler parses the string representation as if it were an http specification. Most URL protocol families have a similar parsing. A stream protocol handler for a protocol that has a different syntax must override this routine.

Parameters
u the URL to receive the result of parsing the spec.
spec the String representing the URL that must be parsed.
start the character index at which to begin parsing. This is just past the ':' (if there is one) that specifies the determination of the protocol name.
limit the character position to stop parsing at. This is the end of the string or the position of the "#" character, if present. All information after the sharp sign indicates an anchor.

protected boolean sameFile (URL u1, URL u2)

Compare two urls to see whether they refer to the same file, i.e., having the same protocol, host, port, and path. This method requires that none of its arguments is null. This is guaranteed by the fact that it is only called indirectly by java.net.URL class.

Parameters
u1 a URL object
u2 a URL object
Returns
  • true if u1 and u2 refer to the same file

protected void setURL (URL u, String protocol, String host, int port, String file, String ref)

This method was deprecated.
Use setURL(URL, String, String, int, String, String, String, String);

Sets the fields of the URL argument to the indicated values. Only classes derived from URLStreamHandler are supposed to be able to call the set method on a URL.

Parameters
u the URL to modify.
protocol the protocol name. This value is ignored since 1.2.
host the remote host value for the URL.
port the port on the remote machine.
file the file.
ref the reference.
Throws
SecurityException if the protocol handler of the URL is different from this one

protected void setURL (URL u, String protocol, String host, int port, String authority, String userInfo, String path, String query, String ref)

Sets the fields of the URL argument to the indicated values. Only classes derived from URLStreamHandler are supposed to be able to call the set method on a URL.

Parameters
u the URL to modify.
protocol the protocol name.
host the remote host value for the URL.
port the port on the remote machine.
authority the authority part for the URL.
userInfo the userInfo part of the URL.
path the path component of the URL.
query the query part for the URL.
ref the reference.
Throws
SecurityException if the protocol handler of the URL is different from this one

protected String toExternalForm (URL u)

Converts a URL of a specific protocol to a String.

Parameters
u the URL.
Returns
  • a string representation of the URL argument.