java处理字节的常用工具类

处理字节的常用工具类方法，供大家参考，具体内容如下

package com.demo.utils;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.charset.Charset;
import java.util.Arrays;


public class ByteUtils {

 
 private static final byte[] BUILD_BYTE_TABLE = new byte[] { (byte) 128, (byte) 64, (byte) 32, (byte) 16, (byte) 8, (byte) 4, (byte) 2, (byte) 1 };

 private ByteUtils() {}

 
 public static byte[] shortToByte(short number) {
  byte[] b = new byte[2];
  for (int i = 1; i >= 0; i--) {
   b[i] = (byte) (number % 256);
   number >>= 8;
  }
  return b;
 }

 
 public static short byteToShort(byte[] b) {
  return (short) ((((b[0] & 0xff) << 8) | b[1] & 0xff));
 }

 
 public static byte[] intToByte(int number) {
  byte[] b = new byte[4];
  for (int i = 3; i >= 0; i--) {
   b[i] = (byte) (number % 256);
   number >>= 8;
  }
  return b;
 }

 
 public static int byteToInt(byte[] b) {
  return ((((b[0] & 0xff) << 24) | ((b[1] & 0xff) << 16) | ((b[2] & 0xff) << 8) | (b[3] & 0xff)));
 }

 
 public static byte[] longToByte(long number) {
  byte[] b = new byte[8];
  for (int i = 7; i >= 0; i--) {
   b[i] = (byte) (number % 256);
   number >>= 8;
  }
  return b;
 }

 
 public static long byteToLong(byte[] b) {
  return ((((long) b[0] & 0xff) << 56) | (((long) b[1] & 0xff) << 48) | (((long) b[2] & 0xff) << 40) | (((long) b[3] & 0xff) << 32) | (((long) b[4] & 0xff) << 24)
    | (((long) b[5] & 0xff) << 16) | (((long) b[6] & 0xff) << 8) | ((long) b[7] & 0xff));
 }

 
 public static byte[] doubleToByte(double d) {
  byte[] bytes = new byte[8];
  long l = Double.doubleToLongBits(d);
  for (int i = 0; i < bytes.length; i++) {
   bytes[i] = Long.valueOf(l).bytevalue();
   l = l >> 8;
  }
  return bytes;
 }

 
 public static double byteToDouble(byte[] b) {
  long l;
  l = b[0];
  l &= 0xff;
  l |= ((long) b[1] << 8);
  l &= 0xffff;
  l |= ((long) b[2] << 16);
  l &= 0xffffff;
  l |= ((long) b[3] << 24);
  l &= 0xffffffffl;
  l |= ((long) b[4] << 32);
  l &= 0xffffffffffl;

  l |= ((long) b[5] << 40);
  l &= 0xffffffffffffl;
  l |= ((long) b[6] << 48);
  l &= 0xffffffffffffffl;

  l |= ((long) b[7] << 56);

  return Double.longBitsToDouble(l);
 }

 
 public static byte[] floatToByte(float d) {
  byte[] bytes = new byte[4];
  int l = Float.floatToIntBits(d);
  for (int i = 0; i < bytes.length; i++) {
   bytes[i] = Integer.valueOf(l).bytevalue();
   l = l >> 8;
  }
  return bytes;
 }

 
 public static float byteToFloat(byte[] b) {
  int l;
  l = b[0];
  l &= 0xff;
  l |= ((long) b[1] << 8);
  l &= 0xffff;
  l |= ((long) b[2] << 16);
  l &= 0xffffff;
  l |= ((long) b[3] << 24);
  l &= 0xffffffffl;

  return Float.intBitsToFloat(l);
 }

 
 public static byte[] stringToByte(String s, Charset charset) {
  return s.getBytes(charset);
 }

 
 public static String byteToString(byte[] b, Charset charset) {
  return new String(b, charset);
 }

 
 public static byte[] objectToByte(Object obj) throws IOException {
  ByteArrayOutputStream buff = new ByteArrayOutputStream();
  ObjectOutputStream out = new ObjectOutputStream(buff);
  out.writeObject(obj);
  try {
   return buff.toByteArray();
  } finally {
   out.close();
  }
 }

 
 public static Object byteToObject(byte[] b) throws IOException, ClassNotFoundException {
  ByteArrayInputStream buff = new ByteArrayInputStream(b);
  ObjectInputStream in = new ObjectInputStream(buff);
  Object obj = in.readObject();
  try {
   return obj;
  } finally {
   in.close();
  }
 }

 
 public static boolean equalsBit(byte a, byte b) {
  return Arrays.equals(byteToBitArray(a), byteToBitArray(b));
 }

 
 public static boolean equalsBit(byte[] a, byte[] b) {
  if (a == b) {
   return true;
  }
  if (a == null || b == null) {
   return false;
  }

  int length = a.length;
  if (b.length != length) {
   return false;
  }

  for (int count = 0; count < a.length; count++) {
   if (!equalsBit(a[count], b[count])) {
    return false;
   }
  }
  return true;
 }

 
 public static String bitString(byte b) {
  StringBuilder buff = new StringBuilder();
  boolean[] array = byteToBitArray(b);
  for (int i = 0; i < array.length; i++) {
   buff.append(array[i] ? 1 : 0);
  }
  return buff.toString();
 }

 
 public static boolean[] byteToBitArray(byte b) {
  boolean[] buff = new boolean[8];
  int index = 0;
  for (int i = 7; i >= 0; i--) {
   buff[index++] = ((b >>> i) & 1) == 1;
  }
  return buff;
 }

 
 public static boolean byteBitValue(byte b, int index) {
  return byteToBitArray(b)[index];
 }

 
 public static byte buildNewByte(boolean[] values) {
  byte b = 0;
  for (int i = 0; i < 8; i++) {
   if (values[i]) {
    b |= BUILD_BYTE_TABLE[i];
   }
  }
  return b;
 }

 
 public static byte changeByteBitValue(byte b, int index, boolean newValue) {
  boolean[] bitValues = byteToBitArray(b);
  bitValues[index] = newValue;
  return buildNewByte(bitValues);
 }

 
 public static byte[] ipAddressBytes(String address) {
  if (address == null || address.length() < 0 || address.length() > 15) {
   throw new IllegalArgumentException("Invalid IP address.");
  }

  final int ipSize = 4;// 最大IP位数
  final char ipSpace = '.';// IP数字的分隔符
  int[] ipNums = new int[ipSize];
  StringBuilder number = new StringBuilder();// 当前操作的数字
  StringBuilder buff = new StringBuilder(address);
  int point = 0;// 当前操作的数字下标,最大到3.
  char currentChar;
  for (int i = 0; i < buff.length(); i++) {
   currentChar = buff.charAt(i);
   if (ipSpace == currentChar) {
    // 当前位置等于最大于序号后,还有字符没有处理表示这是一个错误的IP.
    if (point == ipSize - 1 && buff.length() - (i + 1) > 0) {
     throw new IllegalArgumentException("Invalid IP address.");
    }
    ipNums[point++] = Integer.parseInt(number.toString());
    number.delete(0, number.length());
   } else {
    number.append(currentChar);
   }
  }
  ipNums[point] = Integer.parseInt(number.toString());

  byte[] ipBuff = new byte[ipSize];
  int pointNum = 0;
  for (int i = 0; i < 4; i++) {
   pointNum = Math.abs(ipNums[i]);
   if (pointNum > 255) {
    throw new IllegalArgumentException("Invalid IP address.");
   }
   ipBuff[i] = (byte) (pointNum & 0xff);
  }

  return ipBuff;
 }
}

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