urlstreamhandler.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 549 行 · 第 1/2 页

/*
 * @(#)URLStreamHandler.java	1.55 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package java.net;

import java.io.IOException;

/**
 * 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>.
 * <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 1.48 10/27/00
 * @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.
     *
     * <p>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.
     * NOTE: <B>java.net.HttpURLConnection</B> is found in J2ME CDC profiles 
     * such as J2ME Foundation Profile.
     *
     * @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.
     */
    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.
     */
    protected void parseURL(URL u, String spec, int start, int limit) {
        // These fields may receive context content if this was relative URL
        String protocol = u.getProtocol();
        String authority = u.getAuthority(); 
        String userInfo = u.getUserInfo();
        String host = u.getHost();
        int port = u.getPort();
        String path = u.getPath();
	String query = u.getQuery();

        // This field has already been parsed
        String ref = u.getRef();

	boolean isRelPath = false;
	boolean queryOnly = false;

// FIX: should not assume query if opaque
        // Strip off the query part
	if (start < limit) {
            int queryStart = spec.indexOf('?');
            queryOnly = queryStart == start;
            if ((queryStart != -1) && (queryStart < limit)) {
                query = spec.substring(queryStart+1, limit);
                if (limit > queryStart)
                    limit = queryStart;
                spec = spec.substring(0, queryStart);
            }
	}

	int i = 0;
        // Parse the authority part if any
	if ((start <= limit - 2) && (spec.charAt(start) == '/') &&
	    (spec.charAt(start + 1) == '/')) {
	    start += 2;
	    i = spec.indexOf('/', start);
            if (i < 0) {
	        i = spec.indexOf('?', start);
		if (i < 0)
                    i = limit;
	    }

            host = authority = spec.substring(start, i);

            int ind = authority.indexOf('@');
            if (ind != -1) {
                userInfo = authority.substring(0, ind);
                host = authority.substring(ind+1);
	    } else {
		userInfo = null;
	    }
	    if (host != null) {
		// If the host is surrounded by [ and ] then its an IPv6 
		// literal address as specified in RFC2732
		if (host.length()>0 && (host.charAt(0) == '[')) {
		    if ((ind = host.indexOf(']')) > 2) {
		    
			String nhost = host ;
			host = nhost.substring(0,ind+1);
			if (Inet6Address.
			    textToNumericFormat(host.substring(1, ind)) == null) {
			    throw new IllegalArgumentException(
				"Invalid host: "+ host);
			}

			port = -1 ;
			if (nhost.length() > ind+1) {
			    if (nhost.charAt(ind+1) == ':') {
				++ind ;
				// port can be null according to RFC2396
				if (nhost.length() > (ind + 1)) {
				    port = Integer.parseInt(nhost.substring(ind+1));
                                    if (port<0)
                                        port = -2; // -1 is reserved for "no port"
				}
			    } else {
				throw new IllegalArgumentException(
				    "Invalid authority field: " + authority);
			    }
			}
		    } else {
			throw new IllegalArgumentException(
			    "Invalid authority field: " + authority);
		    }
		} else {
		    ind = host.indexOf(':');
		    port = -1;
		    if (ind >= 0) {
			// port can be null according to RFC2396
			if (host.length() > (ind + 1)) {
			    port = Integer.parseInt(host.substring(ind + 1));
                            if (port<0)
                                port = -2; // -1 is reserved for "no port"
			}
			host = host.substring(0, ind);
		    }
		}
	    } else {
		host = "";
	    }
	    if (port < -1 || port > 65535)
		throw new IllegalArgumentException("Invalid port number :" +
						   port);
	    start = i;
	    // If the authority is defined then the path is defined by the
            // spec only; See RFC 2396 Section 5.2.4.
            if (authority != null && authority.length() > 0)
                path = "";
	} 

 	if (host == null) {
 	    host = "";
 	}

        // Parse the file path if any
	if (start < limit) {
	    if (spec.charAt(start) == '/') {
		path = spec.substring(start, limit);
	    } else if (path != null && path.length() > 0) {
		isRelPath = true;
		int ind = path.lastIndexOf('/');
		String seperator = "";
		if (ind == -1 && authority != null)
		    seperator = "/";
		path = path.substring(0, ind + 1) + seperator +
		         spec.substring(start, limit);
					
	    } else {
		String seperator = (authority != null) ? "/" : "";
		path = seperator + spec.substring(start, limit);
	    }
	} else if (queryOnly && path != null) {
            int ind = path.lastIndexOf('/');
            if (ind < 0)
                ind = 0;
            path = path.substring(0, ind) + "/";
        }
	if (path == null)
	    path = "";

	if (isRelPath) {
            // Remove embedded /./
            while ((i = path.indexOf("/./")) >= 0) {
	        path = path.substring(0, i) + path.substring(i + 2);
	    }
            // Remove embedded /../ if possible
	    i = 0;
	    while ((i = path.indexOf("/../", i)) > 0) {
	        if ((limit = path.lastIndexOf('/', i - 1)) >= 0) {
		    path = path.substring(0, limit) + path.substring(i + 3);
		    i = 0;
	        } else {
		    i = i + 3;
		}
	    }
            // Remove trailing .. if possible
            while (path.endsWith("/..")) {
                i = path.indexOf("/..");
	        if ((limit = path.lastIndexOf('/', i - 1)) >= 0) {
		    path = path.substring(0, limit+1);
	        } else {
		    break;
		}
	    }
	    // Remove starting .
            if (path.startsWith("./") && path.length() > 2)
                path = path.substring(2);

            // Remove trailing .
            if (path.endsWith("/."))
                path = path.substring(0, path.length() -1);
	}

	setURL(u, protocol, host, port, authority, userInfo, path, query, ref);
    }

    /**
     * Returns the default port for a URL parsed by this handler. This method
     * is meant to be overidden by handlers with default port numbers.
     * @return the default port for a <code>URL</code> parsed by this handler.