byte[]与各种数据类型互相转换示例

转载来源：https://www.cnblogs.com/wzhanke/p/4562056.html

在socket开发过程中，通常需要将一些具体的值（这些值可能是各种JAVA类
型）转化为byte[]类型，为此我总结了如下这个示例，贴出来，以便经常翻看

public class TestCase {      /**      * short到字节数组的转换.      */      public static byte[] shortToByte(short number) {          int temp = number;          byte[] b = new byte[2];          for (int i = 0; i < b.length; i++) {              b[i] = new Integer(temp & 0xff).byteValue();// 将最低位保存在最低位              temp = temp >> 8;// 向右移8位          }          return b;      }      /**      * 字节数组到short的转换.      */      public static short byteToShort(byte[] b) {          short s = 0;          short s0 = (short) (b[0] & 0xff);// 最低位          short s1 = (short) (b[1] & 0xff);          s1 <<= 8;          s = (short) (s0 | s1);          return s;      }      /**      * int到字节数组的转换.      */      public static byte[] intToByte(int number) {          int temp = number;          byte[] b = new byte[4];          for (int i = 0; i < b.length; i++) {              b[i] = new Integer(temp & 0xff).byteValue();// 将最低位保存在最低位              temp = temp >> 8;// 向右移8位          }          return b;      }      /**      * 字节数组到int的转换.      */      public static int byteToInt(byte[] b) {          int s = 0;          int s0 = b[0] & 0xff;// 最低位          int s1 = b[1] & 0xff;          int s2 = b[2] & 0xff;          int s3 = b[3] & 0xff;          s3 <<= 24;          s2 <<= 16;          s1 <<= 8;          s = s0 | s1 | s2 | s3;          return s;      }      /**      * long类型转成byte数组      */      public static byte[] longToByte(long number) {          long temp = number;          byte[] b = new byte[8];          for (int i = 0; i < b.length; i++) {              b[i] = new Long(temp & 0xff).byteValue();// 将最低位保存在最低位 temp = temp                                                          // >> 8;// 向右移8位          }          return b;      }      /**      * 字节数组到long的转换.      */      public static long byteToLong(byte[] b) {          long s = 0;          long s0 = b[0] & 0xff;// 最低位          long s1 = b[1] & 0xff;          long s2 = b[2] & 0xff;          long s3 = b[3] & 0xff;          long s4 = b[4] & 0xff;// 最低位          long s5 = b[5] & 0xff;          long s6 = b[6] & 0xff;          long s7 = b[7] & 0xff;          // s0不变          s1 <<= 8;          s2 <<= 16;          s3 <<= 24;          s4 <<= 8 * 4;          s5 <<= 8 * 5;          s6 <<= 8 * 6;          s7 <<= 8 * 7;          s = s0 | s1 | s2 | s3 | s4 | s5 | s6 | s7;          return s;      }      /**      * double到字节数组的转换.      */      public static byte[] doubleToByte(double num) {            byte[] b = new byte[8];            long l = Double.doubleToLongBits(num);            for (int i = 0; i < 8; i++) {                b[i] = new Long(l).byteValue();                l = l >> 8;            }          return b;      }      /**      * 字节数组到double的转换.      */      public static double getDouble(byte[] b) {            long m;            m = b[0];            m &= 0xff;            m |= ((long) b[1] << 8);            m &= 0xffff;            m |= ((long) b[2] << 16);            m &= 0xffffff;            m |= ((long) b[3] << 24);            m &= 0xffffffffl;            m |= ((long) b[4] << 32);            m &= 0xffffffffffl;            m |= ((long) b[5] << 40);            m &= 0xffffffffffffl;            m |= ((long) b[6] << 48);            m &= 0xffffffffffffffl;            m |= ((long) b[7] << 56);            return Double.longBitsToDouble(m);        }      /**      * float到字节数组的转换.      */      public static void floatToByte(float x) {          //先用 Float.floatToIntBits(f)转换成int      }      /**      * 字节数组到float的转换.      */      public static float getFloat(byte[] b) {            // 4 bytes            int accum = 0;            for ( int shiftBy = 0; shiftBy < 4; shiftBy++ ) {                    accum |= (b[shiftBy] & 0xff) << shiftBy * 8;            }            return Float.intBitsToFloat(accum);        }         /**       * char到字节数组的转换.       */       public static byte[] charToByte(char c){          byte[] b = new byte[2];          b[0] = (byte) ((c & 0xFF00) >> 8);          b[1] = (byte) (c & 0xFF);          return b;       }       /**       * 字节数组到char的转换.       */       public static char byteToChar(byte[] b){          char c = (char) (((b[0] & 0xFF) << 8) | (b[1] & 0xFF));          return c;       }      /**      * string到字节数组的转换.      */      public static byte[] stringToByte(String str) throws UnsupportedEncodingException{          return str.getBytes("GBK");      }      /**      * 字节数组到String的转换.      */      public static String bytesToString(byte[] str) {          String keyword = null;          try {              keyword = new String(str,"GBK");          } catch (UnsupportedEncodingException e) {              e.printStackTrace();          }          return keyword;      }      /**      * object到字节数组的转换      */      @Test      public void testObject2ByteArray() throws IOException,              ClassNotFoundException {          // Object obj = "";          Integer[] obj = { 1, 3, 4 };          // // object to bytearray          ByteArrayOutputStream bo = new ByteArrayOutputStream();          ObjectOutputStream oo = new ObjectOutputStream(bo);          oo.writeObject(obj);          byte[] bytes = bo.toByteArray();          bo.close();          oo.close();          System.out.println(Arrays.toString(bytes));          Integer[] intArr = (Integer[]) testByteArray2Object(bytes);          System.out.println(Arrays.asList(intArr));          byte[] b2 = intToByte(123);          System.out.println(Arrays.toString(b2));          int a = byteToInt(b2);          System.out.println(a);      }      /**      * 字节数组到object的转换.      */      private Object testByteArray2Object(byte[] bytes) throws IOException,              ClassNotFoundException {          // byte[] bytes = null;          Object obj;          // bytearray to object          ByteArrayInputStream bi = new ByteArrayInputStream(bytes);          ObjectInputStream oi = new ObjectInputStream(bi);          obj = oi.readObject();          bi.close();          oi.close();          System.out.println(obj);          return obj;      }  }