java byte[] int string 相互转化

public class ByteUtils {

    /**
     * @author:         吴永行
     * @dateTime:      2014-1-20 下午9:56:00
     * @description:
     *
     */
    public static int bytes2Int(byte[] b, int start, int len) {
        int sum = 0;
        int end = start + len;
        for (int i = start; i < end; i++) {
            int n = ((int) b[i]) & 0xff;
            n <<= (--len) * 8;
            sum = sum + n;
        }
        return sum;
    }

    /**
     * @author:         吴永行
     * @dateTime:      2014-1-20 下午10:01:00
     * @description:
     *
     */
    public static String bytes2String(byte[] b, int start, int len) {

     return new String(b,start,len);
    }

    /**
     * @author:         吴永行
     * @dateTime:      2014-1-20 下午10:02:46
     * @description:
     * @param newStr
     * @return
     *
     */
    public static byte[] string2Bytes(String str) {

     return str.getBytes();
    }

    /**
     * @author:         吴永行
     * @dateTime:      2014-1-20 下午10:03:43
     * @description:
     * @param length
     * @param u2
     * @return
     *
     */
    public static byte[] int2Bytes(int value, int len) {
     byte[] b = new byte[len];
     for (int i = 0; i < len; i++) {
            b[len-i-1] = (byte) ((value >> 8 * i) & 0xff);
        }
     return b;
    }

    /**
     * @author:         吴永行
     * @dateTime:      2014-1-20 下午10:06:19
     * @description:
     * @param classByte
     * @param i
     * @param u2
     * @param strLen
     * @return
     *
     */
    public static byte[] bytesReplace(byte[] originalBytes, int offset, int len,
 byte[] replaceBytes) {
        byte[] newBytes = new byte[originalBytes.length
         + (replaceBytes.length - len)];
        System.arraycopy(originalBytes, 0, newBytes, 0, offset);
        System.arraycopy(replaceBytes, 0, newBytes, offset, replaceBytes.length);
        System.arraycopy(originalBytes, offset + len, newBytes, offset
         + replaceBytes.length, originalBytes.length - offset - len);
        return newBytes;
    }

}