byte[]与各种数据类型互相转换示例

    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;
        }  

    }