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DOS/V Power Report 1998 February
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URLStreamHandler.java
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1997-10-27
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/*
* @(#)URLStreamHandler.java 1.19 97/02/10
*
* Copyright (c) 1995, 1996 Sun Microsystems, Inc. All Rights Reserved.
*
* This software is the confidential and proprietary information of Sun
* Microsystems, Inc. ("Confidential Information"). You shall not
* disclose such Confidential Information and shall use it only in
* accordance with the terms of the license agreement you entered into
* with Sun.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
* SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
* PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
* SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
* THIS SOFTWARE OR ITS DERIVATIVES.
*
* CopyrightVersion 1.1_beta
*
*/
package java.net;
import java.io.IOException;
import java.io.InputStream;
import java.io.File;
import java.io.OutputStream;
import java.util.Hashtable;
/**
* The abstract class <code>URLStreamHandler</code> 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 <code>http</code>, <code>ftp</code>, or
* <code>gopher</code>.
* <p>
* In most cases, an instance of a <code>URLStreamHandler</code>
* subclass is not created directly by an application. Rather, the
* first time a protocol name is encountered when constructing a
* <code>URL</code>, the appropriate stream protocol handler is
* automatically loaded.
*
* @author James Gosling
* @version 1.19, 02/10/97
* @see java.net.URL#URL(java.lang.String, java.lang.String, int, java.lang.String)
* @since JDK1.0
*/
public abstract class URLStreamHandler {
/**
* Opens a connection to the object referenced by the
* <code>URL</code> argument.
* This method should be overridden by a subclass.
*
* @param u the URL that this connects to.
* @return a <code>URLConnection</code> object for the <code>URL</code>.
* @exception IOException if an I/O error occurs while opening the
* connection.
* @since JDK1.0
*/
abstract protected URLConnection openConnection(URL u) throws IOException;
/**
* Parses the string representation of a <code>URL</code> into a
* <code>URL</code> object.
* <p>
* If there is any inherited context, then it has already been
* copied into the <code>URL</code> argument.
* <p>
* The <code>parseURL</code> method of <code>URLStreamHandler</code>
* parses the string representation as if it were an
* <code>http</code> 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.
*
* @param u the <code>URL</code> to receive the result of parsing
* the spec.
* @param spec the <code>String</code> representing the URL that
* must be parsed.
* @param start the character index at which to begin parsing. This is
* just past the '<code>:</code>' (if there is one) that
* specifies the determination of the protocol name.
* @param limit the character position to stop parsing at. This is the
* end of the string or the position of the
* "<code>#</code>" character, if present. All information
* after the sharp sign indicates an anchor.
* @since JDK1.0
*/
protected void parseURL(URL u, String spec, int start, int limit) {
String protocol = u.getProtocol();
String host = u.getHost();
int port = u.getPort();
String file = u.getFile();
String ref = u.getRef();
int i;
if ((start <= limit - 2) && (spec.charAt(start) == '/') &&
(spec.charAt(start + 1) == '/')) {
start += 2;
i = spec.indexOf('/', start);
if (i < 0) {
i = limit;
}
int prn = spec.indexOf(':', start);
port = -1;
if ((prn < i) && (prn >= 0)) {
try {
port = Integer.parseInt(spec.substring(prn + 1, i));
} catch(Exception e) {
// ignore bogus port numbers
}
if (prn > start) {
host = spec.substring(start, prn);
}
} else {
host = spec.substring(start, i);
}
start = i;
file = null;
} else if (host == null) {
host = "";
}
if (start < limit) {
if (spec.charAt(start) == '/') {
file = spec.substring(start, limit);
} else if (file != null && file.length() > 0) {
/* relative to the context file - use either
* Unix separators || platform separators
*/
int ind = Math.max(file.lastIndexOf('/'),
file.lastIndexOf(File.separatorChar));
file = file.substring(0, ind) + "/" + spec.substring(start, limit);
} else {
file = "/" + spec.substring(start, limit);
}
}
if ((file == null) || (file.length() == 0)) {
file = "/";
}
while ((i = file.indexOf("/./")) >= 0) {
file = file.substring(0, i) + file.substring(i + 2);
}
while ((i = file.indexOf("/../")) >= 0) {
if ((limit = file.lastIndexOf('/', i - 1)) >= 0) {
file = file.substring(0, limit) + file.substring(i + 3);
} else {
file = file.substring(i + 3);
}
}
u.set(protocol, host, port, file, ref);
}
/**
* Converts a <code>URL</code> of a specific protocol to a
* <code>String</code>.
*
* @param u the URL.
* @return a string representation of the <code>URL</code> argument.
* @since JDK1.0
*/
protected String toExternalForm(URL u) {
String result = u.getProtocol() + ":";
if ((u.getHost() != null) && (u.getHost().length() > 0)) {
result = result + "//" + u.getHost();
if (u.getPort() != -1) {
result += ":" + u.getPort();
}
}
result += u.getFile();
if (u.getRef() != null) {
result += "#" + u.getRef();
}
return result;
}
/**
* Sets the fields of the <code>URL</code> argument to the indicated values.
* Only classes derived from URLStreamHandler are supposed to be able
* to call the set method on a URL.
*
* @param u the URL to modify.
* @param protocol the protocol name.
* @param host the remote host value for the URL.
* @param port the port on the remote machine.
* @param file the file.
* @param ref the reference.
* @see java.net.URL#set(java.lang.String, java.lang.String, int, java.lang.String, java.lang.String)
* @since JDK1.0
*/
protected void setURL(URL u, String protocol, String host, int port,
String file, String ref) {
u.set(protocol, host, port, file, ref);
}
}