MIME Encoding

Quoted printable characters are encoded in the format =XX', where XX’ stands for the hexadecimal value of the character.

The encoder looks as follows:

import java.io.UnsupportedEncodingException;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * It encodes data into quoted printable format.
 *
* @author Daoyuan Li
 */
public class QuotedPrintableEncoder {
    /**
     * Encodes data into quoted printable format.
     * @param s Data to be encoded.
     * @return The encoded data.
     */
    public String encode(String s) {
        byte[] b = null;
        try {
            b = s.getBytes("ISO-8859-1");
        } catch (UnsupportedEncodingException ex) {
            Logger.getLogger(Mail.class.getName()).log(Level.SEVERE, null, ex);
return "";
        }
        String code = "";
        int wc = 0;
        for (int i = 0; i < b.length; i++) {
            byte c = b[i];
            if(c == 13){
                code = code.concat("\n");
                wc = 0;
                continue;
            } else if(c == 10) {
                //do nothing
                continue;
            }
            code = code.concat("=" + Integer.toHexString(c &255).toUpperCase());
            wc += 3;
            if (wc >= 75) {
                code = code.concat("=\n");
                wc = 0;
            }
        }
        return code;
    }

    /**
     * Encodes data into quoted printable format, without soft line breaks.
     * @param s Data to be encoded.
     * @return The encoded data.
     */
    public String encodeWithoutLineBreak(String s) {
        byte[] b = null;
        try{
            b = s.getBytes("ISO-8859-1");
        } catch (UnsupportedEncodingException ex) {
            Logger.getLogger(Mail.class.getName()).log(Level.SEVERE, null, ex);
            return "";
        }
        String code = "";
        for (int i = 0; i < b.length; i++) {
            byte c = b[i];
            if(c == 13){
                code = code.concat("\n");
                continue;
            } else if (c == 10){
//do nothing
                continue;
            }
            code = code.concat("=" + Integer.toHexString(c & 255).toUpperCase());
        }
        return code;
    }
}