Java bencode - BEncoder.java

package bencode;

import java.io.OutputStream;
import java.io.IOException;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.Iterator;
import java.util.Collections;

public class BEncoder {

    public static void bencode(long n, OutputStream out) throws IOException {

        out.write('i');
        out.write(Long.toString(n).getBytes());
        out.write('e');

    }

    public static void bencode(String s, OutputStream out) throws IOException {

        byte[] bytes = s.getBytes("UTF-8");
        out.write(Integer.toString(bytes.length).getBytes());
        out.write(':');
        out.write(bytes);

    }

    public static void bencode(List list, OutputStream out)
            throws IOException, Exception {

        out.write('l');
        Iterator it = list.iterator();
        while (it.hasNext()) {
            Object o = it.next();
            bencode(o, out);
        }
        out.write('e');

    }

    public static void bencode(Map map, OutputStream out)
            throws IOException, Exception {

        out.write('d');
        List keys = new ArrayList(map.keySet());
        Collections.sort(keys);
        Iterator it = keys.iterator();

        while (it.hasNext()) {
            Object o = it.next();
            bencode((String) o, out);
            bencode(map.get(o), out);
        }

        out.write('e');

    }

    public static void bencode(Object o, OutputStream out)
            throws IOException, Exception {

        if (o instanceof String) {
            bencode((String) o, out);
        } else if (o instanceof Number) {
            bencode(((Number) o).longValue(), out);
        } else if (o instanceof List) {
            bencode((List) o, out);
        } else if (o instanceof Map) {
            bencode((Map) o, out);
        } else {
            throw new Exception("Type not supported: " + o.getClass().getName());
        }

    }

}