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Tomcat example source code file (UEncoder.java)

This example Tomcat source code file (UEncoder.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

bitset, bytechunk, c2bconverter, c2bconverter, chararraywriter, encode, encode, io, ioexception, ioexception, string, string, uencoder, unsafe, util, writer

The Tomcat UEncoder.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.util.buf;

import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.BitSet;

/** Efficient implementation for encoders.
 *  This class is not thread safe - you need one encoder per thread.
 *  The encoder will save and recycle the internal objects, avoiding
 *  garbage.
 * 
 *  You can add extra characters that you want preserved, for example
 *  while encoding a URL you can add "/".
 *
 *  @author Costin Manolache
 */
public final class UEncoder {

    private static org.apache.juli.logging.Log log=
        org.apache.juli.logging.LogFactory.getLog(UEncoder.class );
    
    // Not static - the set may differ ( it's better than adding
    // an extra check for "/", "+", etc
    private BitSet safeChars=null;
    private C2BConverter c2b=null;
    private ByteChunk bb=null;

    private String encoding="UTF8";
    private static final int debug=0;
    
    public UEncoder() {
	initSafeChars();
    }

    public void setEncoding( String s ) {
	encoding=s;
    }

    public void addSafeCharacter( char c ) {
	safeChars.set( c );
    }


    /** URL Encode string, using a specified encoding.
     *
     * @param buf The writer
     * @param s string to be encoded
     * @throws IOException If an I/O error occurs
     */
    public void urlEncode( Writer buf, String s )
	throws IOException
    {
	if( c2b==null ) {
	    bb=new ByteChunk(16); // small enough.
	    c2b=new C2BConverter( bb, encoding );
	}

	for (int i = 0; i < s.length(); i++) {
	    int c = (int) s.charAt(i);
	    if( safeChars.get( c ) ) {
		if( debug > 0 ) log("Safe: " + (char)c);
		buf.write((char)c);
	    } else {
		if( debug > 0 ) log("Unsafe:  " + (char)c);
		c2b.convert( (char)c );
		
		// "surrogate" - UTF is _not_ 16 bit, but 21 !!!!
		// ( while UCS is 31 ). Amazing...
		if (c >= 0xD800 && c <= 0xDBFF) {
		    if ( (i+1) < s.length()) {
			int d = (int) s.charAt(i+1);
			if (d >= 0xDC00 && d <= 0xDFFF) {
			    if( debug > 0 ) log("Unsafe:  " + c);
			    c2b.convert( (char)d);
			    i++;
			}
		    }
		}

		c2b.flushBuffer();
		
		urlEncode( buf, bb.getBuffer(), bb.getOffset(),
			   bb.getLength() );
		bb.recycle();
	    }
	}
    }

    /**
     */
    public void urlEncode( Writer buf, byte bytes[], int off, int len)
	throws IOException
    {
	for( int j=off; j< len; j++ ) {
	    buf.write( '%' );
	    char ch = Character.forDigit((bytes[j] >> 4) & 0xF, 16);
	    if( debug > 0 ) log("Encode:  " + ch);
	    buf.write(ch);
	    ch = Character.forDigit(bytes[j] & 0xF, 16);
	    if( debug > 0 ) log("Encode:  " + ch);
	    buf.write(ch);
	}
    }
    
    /**
     * Utility funtion to re-encode the URL.
     * Still has problems with charset, since UEncoder mostly
     * ignores it.
     */
    public String encodeURL(String uri) {
	String outUri=null;
	try {
	    // XXX optimize - recycle, etc
	    CharArrayWriter out = new CharArrayWriter();
	    urlEncode(out, uri);
	    outUri=out.toString();
	} catch (IOException iex) {
	}
	return outUri;
    }
    

    // -------------------- Internal implementation --------------------
    
    // 
    private void init() {
	
    }
    
    private void initSafeChars() {
	safeChars=new BitSet(128);
	int i;
	for (i = 'a'; i <= 'z'; i++) {
	    safeChars.set(i);
	}
	for (i = 'A'; i <= 'Z'; i++) {
	    safeChars.set(i);
	}
	for (i = '0'; i <= '9'; i++) {
	    safeChars.set(i);
	}
	//safe
	safeChars.set('$');
	safeChars.set('-');
	safeChars.set('_');
	safeChars.set('.');

	// Dangerous: someone may treat this as " "
	// RFC1738 does allow it, it's not reserved
	//    safeChars.set('+');
	//extra
	safeChars.set('!');
	safeChars.set('*');
	safeChars.set('\'');
	safeChars.set('(');
	safeChars.set(')');
	safeChars.set(',');	
    }

    private static void log( String s ) {
        if (log.isDebugEnabled())
            log.debug("Encoder: " + s );
    }
}

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