基本数据类型和byte型之间的转换

我们经常用到数据类型之间的转换，下面这个工具类是基本数据类型和byte型之间的转换。

import java.nio.charset.Charset;


public class ByteUtil {
    
    /**
     * short型转换成byte型
     * @param data
     * @return
     */
    public static byte[] shortToBytes(short data) {
        byte[] bytes = new byte[2];
        bytes[0] = (byte) (data & 0xff);
        bytes[1] = (byte) ((data & 0xff00) >> 8);
        return bytes;
    }

    /**
     * char型转换成byte型
     * @param data
     * @return
     */
    public static byte[] charToBytes(char data) {
        byte[] bytes = new byte[2];
        bytes[0] = (byte) (data);
        bytes[1] = (byte) (data >> 8);
        return bytes;
    }

    /**
     * int型转换成byte型
     * @param data
     * @return
     */
    public static byte[] intToBytes(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;
    }

    /**
     * long型转换成byte型
     * @param data
     * @return
     */
    public static byte[] longToBytes(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;
    }

    /**
     * float型转换成byte型
     * @param data
     * @return
     */
    public static byte[] floatToBytes(float data) {
        int intBits = Float.floatToIntBits(data);
        return intToBytes(intBits);
    }

    /**
     * double型转换成byte型
     * @param data
     * @return
     */
    public static byte[] doubleToBytes(double data) {
        long intBits = Double.doubleToLongBits(data);
        return longToBytes(intBits);
    }

    /**
     * String型转换成byte型
     * @param data
     * @param charsetName
     * @return
     */
    public static byte[] stringToBytes(String data, String charsetName) {
        Charset charset = Charset.forName(charsetName);
        return data.getBytes(charset);
    }

    /**
     * String型转换成byte型
     * @param data
     * @return
     */
    public static byte[] stringToBytes(String data) {
        return stringToBytes(data, "GBK");
    }

    /**
     * byte型转换成short型
     * @param bytes
     * @return
     */
    public static short bytesToShort(byte[] bytes) {
        return (short) ((0xff & bytes[0]) | (0xff00 & (bytes[1] << 8)));
    }

    /**
     * byte型转换成char型
     * @param bytes
     * @return
     */
    public static char bytesToChar(byte[] bytes) {
        return (char) ((0xff & bytes[0]) | (0xff00 & (bytes[1] << 8)));
    }

    /**
     * byte型转换成int型
     * @param bytes
     * @return
     */
    public static int bytesToInt(byte[] bytes) {
        return (0xff & bytes[0]) | (0xff00 & (bytes[1] << 8))
                | (0xff0000 & (bytes[2] << 16))
                | (0xff000000 & (bytes[3] << 24));
    }

    /**
     * byte型转换成long型
     * @param bytes
     * @return
     */
    public static long bytesToLong(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));
    }

    /**
     * byte型转换成float型
     * @param bytes
     * @return
     */
    public static float bytesToFloat(byte[] bytes) {
        return Float.intBitsToFloat(bytesToInt(bytes));
    }

    /**
     * byte型转换成double型
     * @param bytes
     * @return
     */
    public static double bytesToDouble(byte[] bytes) {
        long l = bytesToLong(bytes);
        return Double.longBitsToDouble(l);
    }

    /**
     * byte型转换成String型
     * @param bytes
     * @param charsetName
     * @return
     */
    public static String bytesToString(byte[] bytes, String charsetName) {
        return new String(bytes, Charset.forName(charsetName));
    }

    /**
     *  byte型转换成String型
     * @param bytes
     * @return
     */
    public static String bytesToString(byte[] bytes) {
        return bytesToString(bytes, "GBK");
    }
}

写一个demo调用上面的工具类：

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        short s = 122;
        int i = 122;
        long l = 1222222;
        char c = 'a';
        float f = 122.22f;
        double d = 122.22;
        String string = "你好JAVA!";

        System.out.println("s: " + s);
        System.out.println("i: " + i);
        System.out.println("l: " + l);
        System.out.println("c: " + c);
        System.out.println("f: " + f);
        System.out.println("d: " + d);
        System.out.println("string: " + string);

        System.out.println("********调用转换后********");

        System.out.println("s: " + ByteUtil.bytesToShort(ByteUtil.shortToBytes(s)));
        System.out.println("i: " + ByteUtil.bytesToInt(ByteUtil.intToBytes(i)));
        System.out.println("l: " + ByteUtil.bytesToLong(ByteUtil.longToBytes(l)));
        System.out.println("c: " + ByteUtil.bytesToChar(ByteUtil.charToBytes(c)));
        System.out.println("f: " + ByteUtil.bytesToFloat((ByteUtil.floatToBytes(f))));
        System.out.println("d: " + ByteUtil.bytesToDouble(ByteUtil.doubleToBytes(d)));
        System.out.println("string: " + ByteUtil.bytesToString(ByteUtil.stringToBytes(string)));
    }

}

输出结果：

s: 122
i: 122
l: 1222222
c: a
f: 122.22
d: 122.22
string: 你好JAVA!
********调用转换后********
s: 122
i: 122
l: 1222222
c: a
f: 122.22
d: 122.22
string: 你好JAVA!