java - 将 java.net.InetAddress 转换为 long

Question

我想转换 ajava.net.InetAddress并且我与签名/未签名问题作斗争。这样的痛苦。

我在 Java 中读取从短到字节的转换，反之亦然，为什么字节 b =（字节）0xFF 等于整数-1？

结果想出了：

     final byte [] pumpeIPAddressRaw =
        java.net.InetAddress.getByName (pumpeIPAddressName).getAddress ();

     final long pumpeIPAddress =
         ((pumpeIPAddressRaw [0] & 0xFF) << (3*8)) +
         ((pumpeIPAddressRaw [1] & 0xFF) << (2*8)) +
         ((pumpeIPAddressRaw [2] & 0xFF) << (1*8)) +
         (pumpeIPAddressRaw [3] &  0xFF);

     android.util.Log.i (
        Application.TAG, "LOG00120: Setzte Pumpen Addresse : " +
        pumpeIPAddress + ":" + pumpeIPPort);

猜猜日志仍然显示什么：

04-10 13:12:07.398 I/ch.XXXX.remote.Application(24452): LOG00120: Setzte Pumpen Addresse : -1063035647:27015

有人知道我在做什么错吗？

Answer 1

& 0xffbyte在从to转换期间阻止符号扩展int，但您的表达式还包含从intto的转换，long并且您还需要在此转换期间阻止符号扩展：

final long pumpeIPAddress =
      (((pumpeIPAddressRaw [0] & 0xFF) << (3*8)) + 
      ((pumpeIPAddressRaw [1] & 0xFF) << (2*8)) +
      ((pumpeIPAddressRaw [2] & 0xFF) << (1*8)) +
      (pumpeIPAddressRaw [3] &  0xFF)) & 0xffffffffl; 

或者，您可以通过将操作的第二个操作数标记为使用后缀来一步转换 from byteto ：long& 0xfflongl

final long pumpeIPAddress =
      ((pumpeIPAddressRaw [0] & 0xFFl) << (3*8)) + 
      ((pumpeIPAddressRaw [1] & 0xFFl) << (2*8)) +
      ((pumpeIPAddressRaw [2] & 0xFFl) << (1*8)) +
      (pumpeIPAddressRaw [3] &  0xFFl); 

Answer 2

I think that the answer by user2660727 is good, because it uses only standard Java, is short and efficient. Correcting a few issues (negative values, buffer length), my suggested solution is:

InetAddress bar = InetAddress.getByName(ip);
ByteBuffer buffer = ByteBuffer.allocate(Long.BYTES).order(ByteOrder.BIG_ENDIAN);
buffer.put(new byte[] { 0,0,0,0 });
buffer.put(bar.getAddress());
buffer.position(0);
long address = buffer.getLong();

Answer 3

String ip = "127.0.0.1";
InetAddress inetAddress = InetAddress.getByName(ip);

// ByteOrder.BIG_ENDIAN by default
ByteBuffer buffer = ByteBuffer.allocate(Long.SIZE);
buffer.put(inetAddress.getAddress());
buffer.position(0);
Long longValue = buffer.getLong();