Aca van los metodos para tratar tipos y byte arrays.

Enlace Original: http://www.daniweb.com/software-development/java/code/216874

/* ========================= */
	/* "primitive type --> byte[] data" Methods */
	/* ========================= */

	public static byte[] toByta(byte data) {
	    return new byte[]{data};
	}

	public static byte[] toByta(byte[] data) {
	    return data;
	}

	/* ========================= */

	public static byte[] toByta(short data) {
	    return new byte[] {
	        (byte)((data >>  & 0xff),
	        (byte)((data >> 0) & 0xff),
	    };
	}

	public static byte[] toByta(short[] data) {
	    if (data == null) return null;
	    // ----------
	    byte[] byts = new byte[data.length * 2];
	    for (int i = 0; i < data.length; i++) 	        System.arraycopy(toByta(data[i]), 0, byts, i * 2, 2); 	    return byts; 	} 	/* ========================= */ 	public static byte[] toByta(char data) { 	    return new byte[] { 	        (byte)((data >>  & 0xff),
	        (byte)((data >> 0) & 0xff),
	    };
	}

	public static byte[] toByta(char[] data) {
	    if (data == null) return null;
	    // ----------
	    byte[] byts = new byte[data.length * 2];
	    for (int i = 0; i < data.length; i++) 	        System.arraycopy(toByta(data[i]), 0, byts, i * 2, 2); 	    return byts; 	} 	/* ========================= */ 	public static byte[] toByta(int data) { 	    return new byte[] { 	        (byte)((data >> 24) & 0xff),
	        (byte)((data >> 16) & 0xff),
	        (byte)((data >>  & 0xff),
	        (byte)((data >> 0) & 0xff),
	    };
	}

	public static byte[] toByta(int[] data) {
	    if (data == null) return null;
	    // ----------
	    byte[] byts = new byte[data.length * 4];
	    for (int i = 0; i < data.length; i++) 	        System.arraycopy(toByta(data[i]), 0, byts, i * 4, 4); 	    return byts; 	} 	/* ========================= */ 	public static byte[] toByta(long data) { 	    return new byte[] { 	        (byte)((data >> 56) & 0xff),
	        (byte)((data >> 48) & 0xff),
	        (byte)((data >> 40) & 0xff),
	        (byte)((data >> 32) & 0xff),
	        (byte)((data >> 24) & 0xff),
	        (byte)((data >> 16) & 0xff),
	        (byte)((data >>  & 0xff),
	        (byte)((data >> 0) & 0xff),
	    };
	}

	public static byte[] toByta(long[] data) {
	    if (data == null) return null;
	    // ----------
	    byte[] byts = new byte[data.length * 8];
	    for (int i = 0; i < data.length; i++)
	        System.arraycopy(toByta(data[i]), 0, byts, i * 8, 8);
	    return byts;
	}

	/* ========================= */

	public static byte[] toByta(float data) {
	    return toByta(Float.floatToRawIntBits(data));
	}

	public static byte[] toByta(float[] data) {
	    if (data == null) return null;
	    // ----------
	    byte[] byts = new byte[data.length * 4];
	    for (int i = 0; i < data.length; i++)
	        System.arraycopy(toByta(data[i]), 0, byts, i * 4, 4);
	    return byts;
	}

	/* ========================= */

	public static byte[] toByta(double data) {
	    return toByta(Double.doubleToRawLongBits(data));
	}

	public static byte[] toByta(double[] data) {
	    if (data == null) return null;
	    // ----------
	    byte[] byts = new byte[data.length * 8];
	    for (int i = 0; i < data.length; i++) 	        System.arraycopy(toByta(data[i]), 0, byts, i * 8, 8); 	    return byts; 	} 	/* ========================= */ 	public static byte[] toByta(boolean data) { 	    return new byte[]{(byte)(data ? 0x01 : 0x00)}; // bool -> {1 byte}
	}

	public static byte[] toByta(boolean[] data) {
	    // Advanced Technique: The byte array containts information
	    // about how many boolean values are involved, so the exact
	    // array is returned when later decoded.
	    // ----------
	    if (data == null) return null;
	    // ----------
	    int len = data.length;
	    byte[] lena = toByta(len); // int conversion; length array = lena
	    byte[] byts = new byte[lena.length + (len /  + (len % 8 != 0 ? 1 : 0)];
	    // (Above) length-array-length + sets-of-8-booleans +? byte-for-remainder
	    System.arraycopy(lena, 0, byts, 0, lena.length);
	    // ----------
	    // (Below) algorithm by Matthew Cudmore: boolean[] -> bits -> byte[]
	    for (int i = 0, j = lena.length, k = 7; i < data.length; i++) {
	        byts[j] |= (data[i] ? 1 : 0) << k--;
	        if (k < 0) { j++; k = 7; }
	    }
	    // ----------
	    return byts;
	}

	/* ========================= */

	public static byte[] toByta(String data) {
	    return (data == null) ? null : data.getBytes();
	}

	public static byte[] toByta(String[] data) {
	    // Advanced Technique: Generates an indexed byte array
	    // which contains the array of Strings. The byte array
	    // contains information about the number of Strings and
	    // the length of each String.
	    // ----------
	    if (data == null) return null;
	    // ---------- flags:
	    int totalLength = 0; // Measure length of final byte array
	    int bytesPos = 0; // Used later
	    // ----- arrays:
	    byte[] dLen = toByta(data.length); // byte array of data length
	    totalLength += dLen.length;
	    int[] sLens = new int[data.length]; // String lengths = sLens
	    totalLength += (sLens.length * 4);
	    byte[][] strs = new byte[data.length][]; // array of String bytes
	    // ----- pack strs:
	    for (int i = 0; i < data.length; i++) { 	        if (data[i] != null) { 	            strs[i] = toByta(data[i]); 	            sLens[i] = strs[i].length; 	            totalLength += strs[i].length; 	        } else { 	            sLens[i] = 0; 	            strs[i] = new byte[0]; // prevent null entries 	        } 	    } 	    // ---------- 	    byte[] bytes = new byte[totalLength]; // final array 	    System.arraycopy(dLen, 0, bytes, 0, 4); 	    byte[] bsLens = toByta(sLens); // byte version of String sLens 	    System.arraycopy(bsLens, 0, bytes, 4, bsLens.length); 	    // ----- 	    bytesPos += 4 + bsLens.length; // mark position 	    // ----- 	    for (byte[] sba : strs) { 	        System.arraycopy(sba, 0, bytes, bytesPos, sba.length); 	        bytesPos += sba.length; 	    } 	    // ---------- 	    return bytes; 	} 	/* ========================= */ 	/* "byte[] data --> primitive type" Methods */
	/* ========================= */

	public static byte toByte(byte[] data) {
	    return (data == null || data.length == 0) ? 0x0 : data[0];
	}

	public static byte[] toByteA(byte[] data) {
	    return data;
	}

	/* ========================= */

	public static short toShort(byte[] data) {
	    if (data == null || data.length != 2) return 0x0;
	    // ----------
	    return (short)(
	            (0xff & data[0]) < < 8   |
	            (0xff & data[1]) << 0
	            );
	}

	public static short[] toShortA(byte[] data) {
	    if (data == null || data.length % 2 != 0) return null;
	    // ----------
	    short[] shts = new short[data.length / 2];
	    for (int i = 0; i < shts.length; i++) {
	        shts[i] = toShort( new byte[] {
	            data[(i*2)],
	            data[(i*2)+1]
	        } );
	    }
	    return shts;
	}

	/* ========================= */

	public static char toChar(byte[] data) {
	    if (data == null || data.length != 2) return 0x0;
	    // ----------
	    return (char)(
	            (0xff & data[0]) << 8   |
	            (0xff & data[1]) << 0
	            );
	}

	public static char[] toCharA(byte[] data) {
	    if (data == null || data.length % 2 != 0) return null;
	    // ----------
	    char[] chrs = new char[data.length / 2];
	    for (int i = 0; i < chrs.length; i++) {
	        chrs[i] = toChar( new byte[] {
	            data[(i*2)],
	            data[(i*2)+1],
	        } );
	    }
	    return chrs;
	}

	/* ========================= */

	public static int toInt(byte[] data) {
	    if (data == null || data.length != 4) return 0x0;
	    // ----------
	    return (int)( // NOTE: type cast not necessary for int
	            (0xff & data[0]) << 24  |
	            (0xff & data[1]) << 16  |
	            (0xff & data[2]) << 8   |
	            (0xff & data[3]) << 0
	            );
	}

	public static int[] toIntA(byte[] data) {
	    if (data == null || data.length % 4 != 0) return null;
	    // ----------
	    int[] ints = new int[data.length / 4];
	    for (int i = 0; i < ints.length; i++)
	        ints[i] = toInt( new byte[] {
	            data[(i*4)],
	            data[(i*4)+1],
	            data[(i*4)+2],
	            data[(i*4)+3],
	        } );
	    return ints;
	}

	/* ========================= */

	public static long toLong(byte[] data) {
	    if (data == null || data.length !=  return 0x0;
	    // ----------
	    return (long)(
	            // (Below) convert to longs before shift because digits
	            //         are lost with ints beyond the 32-bit limit
	            (long)(0xff & data[0]) << 56  |
	            (long)(0xff & data[1]) << 48  |
	            (long)(0xff & data[2]) << 40  |
	            (long)(0xff & data[3]) << 32  |
	            (long)(0xff & data[4]) << 24  |
	            (long)(0xff & data[5]) << 16  |
	            (long)(0xff & data[6]) << 8   |
	            (long)(0xff & data[7]) << 0
	            );
	}

	public static long[] toLongA(byte[] data) {
	    if (data == null || data.length % 8 != 0) return null;
	    // ----------
	    long[] lngs = new long[data.length / 8];
	    for (int i = 0; i < lngs.length; i++) {
	        lngs[i] = toLong( new byte[] {
	            data[(i*8)],
	            data[(i*8)+1],
	            data[(i*8)+2],
	            data[(i*8)+3],
	            data[(i*8)+4],
	            data[(i*8)+5],
	            data[(i*8)+6],
	            data[(i*8)+7],
	        } );
	    }
	    return lngs;
	}

	/* ========================= */

	public static float toFloat(byte[] data) {
	    if (data == null || data.length != 4) return 0x0;
	    // ---------- simple:
	    return Float.intBitsToFloat(toInt(data));
	}

	public static float[] toFloatA(byte[] data) {
	    if (data == null || data.length % 4 != 0) return null;
	    // ----------
	    float[] flts = new float[data.length / 4];
	    for (int i = 0; i < flts.length; i++) {
	        flts[i] = toFloat( new byte[] {
	            data[(i*4)],
	            data[(i*4)+1],
	            data[(i*4)+2],
	            data[(i*4)+3],
	        } );
	    }
	    return flts;
	}

	/* ========================= */

	public static double toDouble(byte[] data) {
	    if (data == null || data.length !=  return 0x0;
	    // ---------- simple:
	    return Double.longBitsToDouble(toLong(data));
	}

	public static double[] toDoubleA(byte[] data) {
	    if (data == null) return null;
	    // ----------
	    if (data.length % 8 != 0) return null;
	    double[] dbls = new double[data.length / 8];
	    for (int i = 0; i < dbls.length; i++) {
	        dbls[i] = toDouble( new byte[] {
	            data[(i*8)],
	            data[(i*8)+1],
	            data[(i*8)+2],
	            data[(i*8)+3],
	            data[(i*8)+4],
	            data[(i*8)+5],
	            data[(i*8)+6],
	            data[(i*8)+7],
	        } );
	    }
	    return dbls;
	}

	/* ========================= */

	public static boolean toBoolean(byte[] data) {
	    return (data == null || data.length == 0) ? false : data[0] != 0x00;
	}

	public static boolean[] toBooleanA(byte[] data) {
	    // Advanced Technique: Extract the boolean array's length
	    // from the first four bytes in the char array, and then
	    // read the boolean array.
	    // ----------
	    if (data == null || data.length < 4) return null;
	    // ----------
	    int len = toInt(new byte[]{data[0], data[1], data[2], data[3]});
	    boolean[] bools = new boolean[len];
	    // ----- pack bools:
	    for (int i = 0, j = 4, k = 7; i < bools.length; i++) { 	        bools[i] = ((data[j] >> k--) & 0x01) == 1;
	        if (k < 0) { j++; k = 7; }
	    }
	    // ----------
	    return bools;
	}

	/* ========================= */

	public static String toString(byte[] data) {
	    return (data == null) ? null : new String(data);
	}

	public static String[] toStringA(byte[] data) {
	    // Advanced Technique: Extract the String array's length
	    // from the first four bytes in the char array, and then
	    // read the int array denoting the String lengths, and
	    // then read the Strings.
	    // ----------
	    if (data == null || data.length < 4) return null;
	    // ----------
	    byte[] bBuff = new byte[4]; // Buffer
	    // -----
	    System.arraycopy(data, 0, bBuff, 0, 4);
	    int saLen = toInt(bBuff);
	    if (data.length < (4 + (saLen * 4))) return null;
	    // -----
	    bBuff = new byte[saLen * 4];
	    System.arraycopy(data, 4, bBuff, 0, bBuff.length);
	    int[] sLens = toIntA(bBuff);
	    if (sLens == null) return null;
	    // ----------
	    String[] strs = new String[saLen];
	    for (int i = 0, dataPos = 4 + (saLen * 4); i < saLen; i++) { 	        if (sLens[i] > 0) {
	            if (data.length >= (dataPos + sLens[i])) {
	                bBuff = new byte[sLens[i]];
	                System.arraycopy(data, dataPos, bBuff, 0, sLens[i]);
	                dataPos += sLens[i];
	                strs[i] = toString(bBuff);
	            } else return null;
	        }
	    }
	    // ----------
	    return strs;
	}

Url:  http://www.sdtimes.com/link/33618 (ingles)

En mi experiencia, lo que me ha quitado mucho las ganas de volver a trabajar en java para mis proyectos (pequeños y medianos, aclaro) es todo el entorno de apis, frameworks, contenedores y demas carga que viene incluido en un proyecto java, si no queremos usar jsp a  “a pelo”.

Una tienda de aplicaciones que usen el lenguaje de programación de Sun Java tiene un gran potencial debido a los millones de desarrolladores que crean aplicaciones en Java, que lleva en el mercado desde mediados de los noventa. Sun estima que se usan aplicaciones Java en más de 4.500 millones de ordenadores, móviles y otros gadgets. El CEO de Sun, Jonathan Schwartz, ha indicado que en un principio iría enfocada al mercado de PCs, que estima en una comunidad de 1.000 millones de usuarios.

Via – http://www.muycomputer.com

public static boolean send(String replyTo, String from_email, String to_email, String subject, String body, String type) {
boolean sent = false;
try {
Properties prop = new Properties();
prop.setProperty(”mail.smtp.localhost”, “localhost”);
prop.setProperty(”mail.smtp.port”, “25″);
Session session = Session.getDefaultInstance(prop);

Message msg = new MimeMessage(session);
msg.setSubject(subject);

InternetAddress from = new InternetAddress(from_email);
InternetAddress to = new InternetAddress(to_email);
msg.addRecipient(Message.RecipientType.TO, to);
msg.setFrom(from);

Multipart multipart = new MimeMultipart(”related”);

BodyPart htmlPart = new MimeBodyPart();
if (type.equals(”html”)) htmlPart.setContent(body, “text/html”);
else htmlPart.setContent(body, “text/plain”);

multipart.addBodyPart(htmlPart);
msg.setContent(multipart);

Transport transport = session.getTransport(”smtp”);
transport.connect(USERNAME, PASSWORD); // username, password to connect to smtp server
transport.sendMessage(msg, msg.getAllRecipients());
transport.close();

} catch (Exception e) {
System.err.println(”[MailTool] send() : ” + e.getMessage());
e.printStackTrace();
}

return sent;
}