BufferUnderflowException

Question

在蓝牙应用程序中，我从byte[]中的外部设备接收数据。然后将数据放入ByteBuffer以供进一步使用

如下所示

        ByteBuffer localByteBuffer = null;
        byte[] arrayOfByte = new byte[4096];

          int bytes = 0;
          Log.d("ZeoTest", "++++ Listening...");
          while (true) {

              try {
                    bytes = in.read(arrayOfByte);
                    localByteBuffer = ByteBuffer.wrap(arrayOfByte);

                    localByteBuffer.get(arrayOfByte, 0, arrayOfByte.length);

                    Log.d("Zeo", "input :"+((localByteBuffer))); 
                    String data =bytesToHex(arrayOfByte) ;
                    Log.d("Zeo", "input stream :"+(new String(data))); 
                    Log.d("ZeoTest", "++++ Read "+ bytes +" bytes");

              } catch (IOException e) {
                  e.printStackTrace();
                  try { Thread.sleep(0); } catch (InterruptedException ie) {}
              } Log.d("ZeoTest", "++++ Done: test()");

              onReceive(localByteBuffer);}   }

在onReceive中，检查标头是否有效。

如下所示

  public static boolean isValidHeader(EnhancedByteBuffer paramEnhancedByteBuffer)
  {
    boolean bool = false;
    if (paramEnhancedByteBuffer.remaining() < 12);
    while (true)
    {

      paramEnhancedByteBuffer.order(ByteOrder.LITTLE_ENDIAN);
      int i = paramEnhancedByteBuffer.position();
      long l = paramEnhancedByteBuffer.getUint32();
      paramEnhancedByteBuffer.getUint16();
      int j = paramEnhancedByteBuffer.getUint8();
      int k = paramEnhancedByteBuffer.getUint8();
      paramEnhancedByteBuffer.getBoolean();
      paramEnhancedByteBuffer.getUint8();
      int m = paramEnhancedByteBuffer.getUint16();
      paramEnhancedByteBuffer.position(i);
      if ((l == 1196641608L) && (j <= 2) && (k < 14) && (m == MessageType.getMessageContentSize(k)))
        bool = true;
           return bool;
    }
  }

但是在getUint32方法中在流异常下获取缓冲区

可能是什么原因.？

logcat.

   FATAL EXCEPTION: main
java.nio.BufferUnderflowException
at java.nio.HeapByteBuffer.getInt(HeapByteBuffer.java:117)
at com.myzeo.zeo.utility.EnhancedByteBuffer.getUint32(EnhancedByteBuffer.java:87)
at com.myzeo.bluetooth.ZeoTest.isValidHeader(ZeoTest.java:195)
at com.myzeo.bluetooth.ZeoTest.isValidHeader(ZeoTest.java:183)
at com.myzeo.bluetooth.ZeoTest.onReceive(ZeoTest.java:153)
at com.myzeo.bluetooth.ZeoTest.setup(ZeoTest.java:125)
at com.myzeo.bluetooth.ZeoTest.access$0(ZeoTest.java:64)
at com.myzeo.bluetooth.ZeoTest$1.onClick(ZeoTest.java:47)   
at android.view.View.performClick(View.java:2629)
at android.view.View$PerformClick.run(View.java:9374)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3683)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)

Answer 1

可能的原因是您从缓冲区中读取的字节比可用的字节多。在调试器中的每个read()之后检查缓冲区的位置，看看哪个调用比它更多地推进了缓冲区(可能是readBoolean())

Answer 2

你没有考虑到阅读头的位置。

如果您想获得一个整数值，并且读取头位于容量为4的ByteBuffer的第4位置，那么您将得到一个BufferUnderflowException，因为他不能再读取4个字节来返回整数值。

你必须给他阅读的位置(非持久性)：getInt(位置);，例如: getInt( 0 )；