handler.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: Handler.java,v 1.7 2005/06/18 21:33:29 bondolo Exp $
 */

package sun.net.www.protocol.urn;

import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;

import java.io.IOException;

/**
 * Handler for URN
 *
 * @deprecated Use the URI interfaces for JXTA IDs instead of the URLs.
 */
public final class Handler extends URLStreamHandler {
    
    public static Handler handler = new Handler();
    
    /**
     * Creates new Handler
     **/
    public Handler() { }
    
    /**
     *
     **/
    public URLConnection openConnection( URL connect ) throws
    IOException {
        return null;
    }
    
    /**
     *
     *  Private replacement for toHexString since we need the leading 0 digits.
     *  Returns a String containing byte value encoded as 2 hex characters.
     *
     *  @param  theByte a byte containing the value to be encoded.
     *  @return	String containing byte value encoded as 2 hex characters.
     */
    private static String toHexDigits( byte theByte ) {
        final char [] HEXDIGITS = { '0', '1', '2', '3', '4', '5', '6', '7',
        '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
        StringBuffer result = new StringBuffer(2);
        
        result.append( HEXDIGITS[(theByte >>> 4) & 15] );
        result.append( HEXDIGITS[theByte & 15] );
        
        return result.toString();
    }
    
    /**
     *
     * 2.4 of RFC2141 says we have to encode these chars.
     *
     **/
    static final String needsEncoding = "%/?#" + "\\\"&<>[]^`{|}~";
    
    /**
     *
     * The byte values of the chars we have to encode.
     *
     **/
    static final byte[] encodesTo = new byte[] {
        0x25, 0x2F, 0x3F, 0x23,
        0x5c, 0x22, 0x26, 0x3C, 0x3E, 0x5B, 0x5D,
        0x5E, 0x60, 0x7B, 0x7C, 0x7D, 0x7E
    };
    
    /**
     *  Encode a string such that it is in a form acceptable for presentation
     *  as a URN. First the string is encoded as UTF8 so that any high byte
     *  unicode chars are ascii representable. Then any special characters in
     *  the string are escaped using the URN % syntax.
     *
     *  @param source   the string to encode
     *  @return String containing the URN acceptable presentation form.
     **/
    public static String encodeURN( String source ) {
        String asISO8559_1 = null;
        
        try {
            // first we get its bytes using UTF to encode its characters.
            byte [] asBytes = source.getBytes( "UTF8" );
            
            // then read it back in as ISO-8859-1. This allows us to see the
            // bytes with no translation. This string will have chars in the
            // range 0-255 only.
            asISO8559_1 = new String( asBytes, "ISO-8859-1" );
        } catch( java.io.UnsupportedEncodingException never ) {
            // these 2 encodings are required by all java implementations
            // so this exception will never happen.
            ;
        }
        
        StringBuffer result = new StringBuffer( asISO8559_1.length() );
        
        // now do the % encoding for all chars which need it.
        for( int eachChar = 0; eachChar < asISO8559_1.length(); eachChar++ ) {
            char aChar = asISO8559_1.charAt( eachChar );
            
            // null char is bad
            if( 0 == aChar )
                throw new IllegalArgumentException( "URN string cannot contain null char" );
            
            // in the excluded range
            if( (aChar <= 32) || (aChar >= 127) ) {
                result.append( '%' );
                result.append( toHexDigits( (byte) aChar ) );
            } else {
                int inSpecials = needsEncoding.indexOf(aChar);
                
                // one of the special chars which must be encoded?
                if( -1 != inSpecials ) {
                    result.append( '%' );
                    result.append( toHexDigits( encodesTo[inSpecials] ) );
                } else
                    result.append( aChar ); // needed no encoding
            }
        }
        
        return result.toString();
    }
    
    /**
     *  Converts a string which was previously conveted to URN format back into
     *  the unencoded format.
     *
     *  @param source   the string to decode
     *  @return String containing the decoded form of the URN.
     **/
    public static String decodeURN( String source ) {
        StringBuffer result = new StringBuffer( source.length() );
        
        // remove the % encoding for all chars which needed it.
        for( int eachChar = 0; eachChar < source.length(); eachChar++ ) {
            char aChar = source.charAt( eachChar );
            
            if( '%' != aChar )
                result.append( aChar );
            else {
                String twoChars = source.substring( eachChar + 1, eachChar + 3 );
                result.append( (char) Integer.parseInt( twoChars, 16 ) );
                eachChar += 2;
            }
        }
        
        String fromUTF8 = null;
        
        try {
            // first we get its bytes using ISO-8859-1 to encode its characters.
            // ISO-8859-1 does no mapping. Each byte is the same as the character.
            byte [] asBytes = result.toString().getBytes( "ISO-8859-1" );
            
            // then read it back in as UTF8. This gets us any high byte chars back
            fromUTF8 = new String( asBytes, "UTF8" );
        } catch( java.io.UnsupportedEncodingException never ) {
            // these 2 encodings are required so this exception will never happen
            ;
        }
        
        return fromUTF8;
    }
}