java整數與byte數組的轉換實現代碼

public class NumberUtil { 
  /** 
   * int整數轉換為4字節的byte數組 
   * 
   * @param i 
   *      整數 
   * @return byte數組 
   */ 
  public static byte[] intToByte4(int i) { 
    byte[] targets = new byte[4]; 
    targets[3] = (byte) (i & 0xFF); 
    targets[2] = (byte) (i >> 8 & 0xFF); 
    targets[1] = (byte) (i >> 16 & 0xFF); 
    targets[0] = (byte) (i >> 24 & 0xFF); 
    return targets; 
  } 
 
  /** 
   * long整數轉換為8字節的byte數組 
   * 
   * @param lo 
   *      long整數 
   * @return byte數組 
   */ 
  public static byte[] longToByte8(long lo) { 
    byte[] targets = new byte[8]; 
    for (int i = 0; i < 8; i++) { 
      int offset = (targets.length - 1 - i) * 8; 
      targets[i] = (byte) ((lo >>> offset) & 0xFF); 
    } 
    return targets; 
  } 
 
  /** 
   * short整數轉換為2字節的byte數組 
   * 
   * @param s 
   *      short整數 
   * @return byte數組 
   */ 
  public static byte[] unsignedShortToByte2(int s) { 
    byte[] targets = new byte[2]; 
    targets[0] = (byte) (s >> 8 & 0xFF); 
    targets[1] = (byte) (s & 0xFF); 
    return targets; 
  } 
 
  /** 
   * byte數組轉換為無符號short整數 
   * 
   * @param bytes 
   *      byte數組 
   * @return short整數 
   */ 
  public static int byte2ToUnsignedShort(byte[] bytes) { 
    return byte2ToUnsignedShort(bytes, 0); 
  } 
 
  /** 
   * byte數組轉換為無符號short整數 
   * 
   * @param bytes 
   *      byte數組 
   * @param off 
   *      開始位置 
   * @return short整數 
   */ 
  public static int byte2ToUnsignedShort(byte[] bytes, int off) { 
    int high = bytes[off]; 
    int low = bytes[off + 1]; 
    return (high << 8 & 0xFF00) | (low & 0xFF); 
  } 
 
  /** 
   * byte數組轉換為int整數 
   * 
   * @param bytes 
   *      byte數組 
   * @param off 
   *      開始位置 
   * @return int整數 
   */ 
  public static int byte4ToInt(byte[] bytes, int off) { 
    int b0 = bytes[off] & 0xFF; 
    int b1 = bytes[off + 1] & 0xFF; 
    int b2 = bytes[off + 2] & 0xFF; 
    int b3 = bytes[off + 3] & 0xFF; 
    return (b0 << 24) | (b1 << 16) | (b2 << 8) | b3; 
  } 
}