public UEncoder() 
{
	initSafeChars();
}

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

 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;
}

Utility funtion to re-encode the URL. Still has problems with charset, since UEncoder mostly ignores it.

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

 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();
	    }
	}
}

URL Encode string, using a specified encoding.

 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);
	}
}