Java自定义协议报文封装 添加Crc32校验的实例

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
/**
 * Created by SiKang on 2016/4/29.
 */
public class CustomData {
 public static void main(String args[]) {
  //服务端线程
  new Thread(new Runnable() {
   @Override
   public void run() {
    try {
     //开启服务端Socket
     ServerSocket server = new ServerSocket(9000);
     //等待客户端连接
     Socket socket = server.accept();
     InputStream inputStream = socket.getInputStream();
     //先得到前两个字节 为报文长度
     byte[] lenBytes = new byte[2];
     inputStream.read(lenBytes);
     short length = bytesToShort(lenBytes);
   System.out.println("length: " + length);
     //然后得到接下来的四个字节 crc32校验码
     byte[] crc = new byte[4];
     inputStream.read(crc);
     int crc32 = bytesToInt(crc);
     //得到剩下的字段 ver、cmd、data
     byte[] bytes = new byte[length - 2 - 4];
     inputStream.read(bytes);
     //根据得到的bytes获取新的Crc32校验码 验证数据是否完整（可以在读取bytes时少读一位，看看能不能通过）
     if (crc32 == getCRC32(bytes)) {
      System.out.println("Crc32 Right!");
     }else{
   System.out.println("Crc32 Error!");
      return;
   }
     //取出ver cmd
     int ver = Integer.parseInt(byteToHex(bytes[0]),16);
     int cmd = Integer.parseInt(byteToHex(bytes[1]),16);
     //看看ver是否是客户端发送0x05
     if (ver == 0x05) {
      System.out.println("ver: 0x05");
     }
     //cmd是否是客户端发送0xff
     if (cmd == 0xff) {
      System.out.println("cmd: 0xff");
     }
     //得到剩下的数据字节数，取出data数据
     int datalen = length - 2 - 4 - 1 - 1;
     byte[] data = new byte[datalen];
     int index = 1;
     for (int i = 0; i < datalen; i++) {
      data[i] = bytes[++index];
     }
     String str = new String(data);
     System.out.println("data: " + str);
     inputStream.close();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }).start();
  //客户端线程
  new Thread(new Runnable() {
   @Override
   public void run() {
    try {
     //连接服务端
     Socket socket = new Socket(getIpAddress(),9000);
     OutputStream outputStream = socket.getOutputStream();
     String str = "Hellow World!";
     byte[] data = str.getBytes();
     //发送报文
     pack(outputStream,(byte) 0xff,data,data.length);
     outputStream.flush();
     outputStream.close();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }).start();
 }
 /**
 *封装并发送报文
 *这里报文格式为{报文总长度[2字节]，Crc32校验码[4字节]，ver版本信息[1字节]，cmd指令[1字节]，data数据内容[若干字节]}
 */
 private static void pack(OutputStream out,byte cmd,byte[] data,int len) {
  try {
   //先得到报文总长度，如上介绍的格式 字节数相加
   short totalSize = (short) (2 + 4 + 1 + 1 + len);
   //输出报文长度
   out.write(shortToByte(totalSize),2);
   //需要校验的字段
   byte[] bytes = new byte[1 + 1 + len];
   int index = 0;
   bytes[index++] = 0x05;//版本号（这里是写死的）
   bytes[index++] = cmd;//cmd指令
   //数据内容
   for (int i = 0; i < len; i++) {
    bytes[index++] = data[i];
   }
   //得到ver、cmd、data的crc32校验码（Crc32算法在最下边，网上找的.....）
   byte[] crc32 = intToBytes(getCRC32(bytes));
   //输出crc校验码
   out.write(crc32,crc32.length);
   //输出ver、cmd、data
   out.write(bytes,bytes.length);
  } catch (IOException e) {
   e.printStackTrace();
  }
 }

 /**
  * 得到本机IP
  */
 private static String getIpAddress() throws UnknownHostException {
  InetAddress address = InetAddress.getLocalHost();
  return address.getHostAddress();
 }
 /**
  * int转byte[]
  */
 public static byte[] intToBytes(int value) {
  byte[] bytes = new byte[4];
  bytes[3] = (byte) (value >> 24);
  bytes[2] = (byte) (value >> 16);
  bytes[1] = (byte) (value >> 8);
  bytes[0] = (byte) (value >> 0);
  return bytes;
 }
 /**
  * short转byte[]
  */
 public static byte[] shortToByte(short value) {
  byte[] bytes = new byte[2];
  bytes[1] = (byte) (value >> 8);
  bytes[0] = (byte) (value >> 0);
  return bytes;
 }
 /**
  * byte转16进制
  */
 public static String byteToHex(byte b) {
  int i = b & 0xFF;
  return Integer.toHexString(i);
 }
 /**
  * byte[]转int
  */
 public static int bytesToInt(byte[] bytes) {
  return (int) ((((bytes[3] & 0xff) << 24)
    | ((bytes[2] & 0xff) << 16)
    | ((bytes[1] & 0xff) << 8) | ((bytes[0] & 0xff) << 0)));
 }
 /**
  * byte[]转short
  */
 public static short bytesToShort(byte[] bytes) {
  return (short) (((bytes[1] << 8) | bytes[0] & 0xff));
 }
 /**
  * 得到CRC32校验码
  */
 public static int getCRC32(byte[] bytes) {
  int[] table = {
    0x00000000,0x77073096,0xee0e612c,0x990951ba,0x076dc419,0x706af48f,0xe963a535,0x9e6495a3,0x0edb8832,0x79dcb8a4,0xe0d5e91e,0x97d2d988,0x09b64c2b,0x7eb17cbd,0xe7b82d07,0x90bf1d91,0x1db71064,0x6ab020f2,0xf3b97148,0x84be41de,0x1adad47d,0x6ddde4eb,0xf4d4b551,0x83d385c7,0x136c9856,0x646ba8c0,0xfd62f97a,0x8a65c9ec,0x14015c4f,0x63066cd9,0xfa0f3d63,0x8d080df5,0x3b6e20c8,0x4c69105e,0xd56041e4,0xa2677172,0x3c03e4d1,0x4b04d447,0xd20d85fd,0xa50ab56b,0x35b5a8fa,0x42b2986c,0xdbbbc9d6,0xacbcf940,0x32d86ce3,0x45df5c75,0xdcd60dcf,0xabd13d59,0x26d930ac,0x51de003a,0xc8d75180,0xbfd06116,0x21b4f4b5,0x56b3c423,0xcfba9599,0xb8bda50f,0x2802b89e,0x5f058808,0xc60cd9b2,0xb10be924,0x2f6f7c87,0x58684c11,0xc1611dab,0xb6662d3d,0x76dc4190,0x01db7106,0x98d220bc,0xefd5102a,0x71b18589,0x06b6b51f,0x9fbfe4a5,0xe8b8d433,0x7807c9a2,0x0f00f934,0x9609a88e,0xe10e9818,0x7f6a0dbb,0x086d3d2d,0x91646c97,0xe6635c01,0x6b6b51f4,0x1c6c6162,0x856530d8,0xf262004e,0x6c0695ed,0x1b01a57b,0x8208f4c1,0xf50fc457,0x65b0d9c6,0x12b7e950,0x8bbeb8ea,0xfcb9887c,0x62dd1ddf,0x15da2d49,0x8cd37cf3,0xfbd44c65,0x4db26158,0x3ab551ce,0xa3bc0074,0xd4bb30e2,0x4adfa541,0x3dd895d7,0xa4d1c46d,0xd3d6f4fb,0x4369e96a,0x346ed9fc,0xad678846,0xda60b8d0,0x44042d73,0x33031de5,0xaa0a4c5f,0xdd0d7cc9,0x5005713c,0x270241aa,0xbe0b1010,0xc90c2086,0x5768b525,0x206f85b3,0xb966d409,0xce61e49f,0x5edef90e,0x29d9c998,0xb0d09822,0xc7d7a8b4,0x59b33d17,0x2eb40d81,0xb7bd5c3b,0xc0ba6cad,0xedb88320,0x9abfb3b6,0x03b6e20c,0x74b1d29a,0xead54739,0x9dd277af,0x04db2615,0x73dc1683,0xe3630b12,0x94643b84,0x0d6d6a3e,0x7a6a5aa8,0xe40ecf0b,0x9309ff9d,0x0a00ae27,0x7d079eb1,0xf00f9344,0x8708a3d2,0x1e01f268,0x6906c2fe,0xf762575d,0x806567cb,0x196c3671,0x6e6b06e7,0xfed41b76,0x89d32be0,0x10da7a5a,0x67dd4acc,0xf9b9df6f,0x8ebeeff9,0x17b7be43,0x60b08ed5,0xd6d6a3e8,0xa1d1937e,0x38d8c2c4,0x4fdff252,0xd1bb67f1,0xa6bc5767,0x3fb506dd,0x48b2364b,0xd80d2bda,0xaf0a1b4c,0x36034af6,0x41047a60,0xdf60efc3,0xa867df55,0x316e8eef,0x4669be79,0xcb61b38c,0xbc66831a,0x256fd2a0,0x5268e236,0xcc0c7795,0xbb0b4703,0x220216b9,0x5505262f,0xc5ba3bbe,0xb2bd0b28,0x2bb45a92,0x5cb36a04,0xc2d7ffa7,0xb5d0cf31,0x2cd99e8b,0x5bdeae1d,0x9b64c2b0,0xec63f226,0x756aa39c,0x026d930a,0x9c0906a9,0xeb0e363f,0x72076785,0x05005713,0x95bf4a82,0xe2b87a14,0x7bb12bae,0x0cb61b38,0x92d28e9b,0xe5d5be0d,0x7cdcefb7,0x0bdbdf21,0x86d3d2d4,0xf1d4e242,0x68ddb3f8,0x1fda836e,0x81be16cd,0xf6b9265b,0x6fb077e1,0x18b74777,0x88085ae6,0xff0f6a70,0x66063bca,0x11010b5c,0x8f659eff,0xf862ae69,0x616bffd3,0x166ccf45,0xa00ae278,0xd70dd2ee,0x4e048354,0x3903b3c2,0xa7672661,0xd06016f7,0x4969474d,0x3e6e77db,0xaed16a4a,0xd9d65adc,0x40df0b66,0x37d83bf0,0xa9bcae53,0xdebb9ec5,0x47b2cf7f,0x30b5ffe9,0xbdbdf21c,0xcabac28a,0x53b39330,0x24b4a3a6,0xbad03605,0xcdd70693,0x54de5729,0x23d967bf,0xb3667a2e,0xc4614ab8,0x5d681b02,0x2a6f2b94,0xb40bbe37,0xc30c8ea1,0x5a05df1b,0x2d02ef8d,};
  int crc = 0xffffffff;
  for (byte b : bytes) {
   crc = (crc >>> 8 ^ table[(crc ^ b) & 0xff]);
  }
  crc = crc ^ 0xffffffff;
  return crc;
 }
}