java基本类型和byte[]转换

 

public class ByteUtil {
    public static byte[] getBytes(short data) {
        byte[] bytes = new byte[2];
        bytes[0] = (byte) (data & 0xff);
        bytes[1] = (byte) ((data & 0xff00) >> 8);
        return bytes;
    }

    public static byte[] getBytes(char data) {
        byte[] bytes = new byte[2];
        bytes[0] = (byte) (data);
        bytes[1] = (byte) (data >> 8);
        return bytes;
    }

    public static byte[] getBytes(int data) {
        byte[] bytes = new byte[4];
        bytes[0] = (byte) (data & 0xff);
        bytes[1] = (byte) ((data & 0xff00) >> 8);
        bytes[2] = (byte) ((data & 0xff0000) >> 16);
        bytes[3] = (byte) ((data & 0xff000000) >> 24);
        return bytes;
    }

    public static byte[] getBytes(long data) {
        byte[] bytes = new byte[8];
        bytes[0] = (byte) (data & 0xff);
        bytes[1] = (byte) ((data >> 8) & 0xff);
        bytes[2] = (byte) ((data >> 16) & 0xff);
        bytes[3] = (byte) ((data >> 24) & 0xff);
        bytes[4] = (byte) ((data >> 32) & 0xff);
        bytes[5] = (byte) ((data >> 40) & 0xff);
        bytes[6] = (byte) ((data >> 48) & 0xff);
        bytes[7] = (byte) ((data >> 56) & 0xff);
        return bytes;
    }

    public static byte[] getBytes(float data) {
        int intBits = Float.floatToIntBits(data);
        return getBytes(intBits);
    }

    public static byte[] getBytes(double data) {
        long intBits = Double.doubleToLongBits(data);
        return getBytes(intBits);
    }


    public static short getShort(byte[] bytes) {
        return (short) ((0xff & bytes[0]) | (0xff00 & (bytes[1] << 8)));
    }

    public static char getChar(byte[] bytes) {
        return (char) ((0xff & bytes[0]) | (0xff00 & (bytes[1] << 8)));
    }

    public static int getInt(byte[] bytes) {
        return (0xff & bytes[0])
                | (0xff00 & (bytes[1] << 8))
                | (0xff0000 & (bytes[2] << 16))
                | (0xff000000 & (bytes[3] << 24));
    }

    public static long getLong(byte[] bytes) {
        return (0xffL & (long) bytes[0]) | (0xff00L & ((long) bytes[1] << 8)) | (0xff0000L & ((long) bytes[2] << 16)) | (0xff000000L & ((long) bytes[3] << 24))
                | (0xff00000000L & ((long) bytes[4] << 32)) | (0xff0000000000L & ((long) bytes[5] << 40)) | (0xff000000000000L & ((long) bytes[6] << 48)) | (0xff00000000000000L & ((long) bytes[7] << 56));
    }

    public static float getFloat(byte[] bytes) {
        return Float.intBitsToFloat(getInt(bytes));
    }

    public static double getDouble(byte[] bytes) {
        long l = getLong(bytes);
        return Double.longBitsToDouble(l);
    }


    public static byte[] intToByteArray(int i) {
        byte[] bytes = new byte[4];
        bytes[0] = (byte) i;
        bytes[1] = (byte) (i >> 8);
        bytes[2] = (byte) (i >> 16);
        bytes[3] = (byte) (i >> 24);
        return bytes;
    }

    public static int byteArrayToInt(byte[] bytes) {
        int res = 0;
        for (int i = 0; i < bytes.length; i++) {
            res += (bytes[i] & 0xff) << i * 8;
        }
        return res;
    }

    public static void main(String[] args) {
        short s=257;
        char c='z';
        int i=-1234567;
        long l=7890000L;
        float f=-1.0f;
        double d=12345.67890d;
        byte[] bytes = getBytes(s);
        System.out.println(getShort(bytes));
        byte[] bytes1 = getBytes(c);
        System.out.println(getChar(bytes1));
        byte[] bytes2 = getBytes(i);
        System.out.println(getInt(bytes2));
        byte[] bytes3 = getBytes(l);
        System.out.println(getLong(bytes3));
        byte[] bytes4 = getBytes(f);
        System.out.println(getFloat(bytes4));
        byte[] bytes5 = getBytes(d);
        System.out.println(getDouble(bytes5));

    }


}