字节数组与16进制字符串之间的转换

/**
 * Created by Administrator on 16-1-19.
 */
public class ByteHex {

/* Convert byte[] to hex string.这里我们可以将byte转换成int，然后利用Integer.toHexString(int)来转换成16进制字符串。
    * @param src byte[] data
    * @return hex string
    */
    public static String bytesToHexString(byte[] src){
        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
return null;
        }
for (int i = 0; i < src.length; i++) {
int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
return stringBuilder.toString();
    }

public static String bytesToHexString(byte[] src,int start,int length){
        StringBuilder stringBuilder = new StringBuilder("");
        if (src == null || src.length <= 0) {
return null;
        }
for (int i = start; i < length; i++) {
int v = src[i] & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
return stringBuilder.toString();
    }
/**
     * Convert hex string to byte[]
     * @param hexString the hex string
     * @return byte[]
     */
    public static byte[] hexStringToBytes(String hexString) {
if (hexString == null || hexString.equals("")) {
return null;
        }
        hexString = hexString.toUpperCase();
        int length = hexString.length() / 2;
        char[] hexChars = hexString.toCharArray();
        byte[] d = new byte[length];
        for (int i = 0; i < length; i++) {
int pos = i * 2;
            d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
        }
return d;
    }
/**
     * Convert char to byte
     * @param c char
     * @return byte
     */
    private static byte charToByte(char c) {
return (byte) "0123456789ABCDEF".indexOf(c);
    }

public static void main(String args[])throws Exception{
byte[] bytes = hexStringToBytes("87");
        System.out.print(bytesToHexString(bytes));
    }
}