Java tutorial
//package com.java2s; import java.io.ByteArrayOutputStream; import java.io.DataOutputStream; import java.io.IOException; public class Main { public static byte[] getBodyBytes(String ip, String port, String key) throws NumberFormatException, IOException { String[] ipArr = ip.split("\\."); byte[] ipByte = new byte[4]; ipByte[0] = (byte) (Integer.parseInt(ipArr[0]) & 0xFF); ipByte[1] = (byte) (Integer.parseInt(ipArr[1]) & 0xFF); ipByte[2] = (byte) (Integer.parseInt(ipArr[2]) & 0xFF); ipByte[3] = (byte) (Integer.parseInt(ipArr[3]) & 0xFF); ByteArrayOutputStream baos = new ByteArrayOutputStream(); DataOutputStream dos = new DataOutputStream(baos); dos.write(ipByte); dos.writeShort(Short.parseShort(port)); dos.writeByte(key.getBytes().length); dos.write(key.getBytes()); byte[] bs = baos.toByteArray(); baos.close(); dos.close(); return bs; } }