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;  
        }  
      
    }