import java.util.BitSet;
import java.io.ByteArrayOutputStream;
import java.io.OutputStreamWriter;
import java.io.IOException;

public class TestEscape {
    static BitSet dontNeedEncoding;
    static final int caseDiff = ('a' - 'A');

    static {
	dontNeedEncoding = new BitSet(256);
	int i;
	for (i = 'a'; i <= 'z'; i++) {
	    dontNeedEncoding.set(i);
	}
	for (i = 'A'; i <= 'Z'; i++) {
	    dontNeedEncoding.set(i);
	}
	for (i = '0'; i <= '9'; i++) {
	    dontNeedEncoding.set(i);
	}
	dontNeedEncoding.set(' '); /* encoding a space to a + is done in the encode() method */
	dontNeedEncoding.set('-');
	dontNeedEncoding.set('_');
	dontNeedEncoding.set('.');
	dontNeedEncoding.set('*');
	dontNeedEncoding.set(0xe5); // å
	dontNeedEncoding.set(0xe4); // ä
	dontNeedEncoding.set(0xf6); // ö
	dontNeedEncoding.set(0xc5); // Å
	dontNeedEncoding.set(0xc4); // Ä
	dontNeedEncoding.set(0xd6); // Ö
    }



    // %E5 %E4 %F6 %C5 %C4 %D6 == åäöÅÄÖ
    // 229 228 246 197 196 214 == åäöÅÄÖ
    public static String encode(String s) {
	int maxBytesPerChar = 10;
        StringBuffer out = new StringBuffer(s.length());
	ByteArrayOutputStream buf = new ByteArrayOutputStream(maxBytesPerChar);
	OutputStreamWriter writer = new OutputStreamWriter(buf);

	for (int i = 0; i < s.length(); i++) {
	    int c = (int)s.charAt(i);
	    if (dontNeedEncoding.get(c)) {
		if (c == ' ') {
		    c = '+';
		}
		out.append((char)c);
	    } else {
		// convert to external encoding before hex conversion
		try {
		    writer.write(c);
		    writer.flush();
		} catch(IOException e) {
		    buf.reset();
		    continue;
		}
		byte[] ba = buf.toByteArray();
		for (int j = 0; j < ba.length; j++) {
		    out.append('%');
		    char ch = Character.forDigit((ba[j] >> 4) & 0xF, 16);
		    // converting to use uppercase letter as part of
		    // the hex value if ch is a letter.
		    if (Character.isLetter(ch)) {
			ch -= caseDiff;
		    }
		    out.append(ch);
		    ch = Character.forDigit(ba[j] & 0xF, 16);
		    if (Character.isLetter(ch)) {
			ch -= caseDiff;
		    }
		    out.append(ch);
		}
		buf.reset();
	    }
	}

	return out.toString();
    }


    public static void main(String[] argv) {
	System.out.println(encode("puffo&miffoÅÄÖåäömiffo"));
    }
}