使用BufferUnderflowException和序列化时的Java

Question

我试图编写一个程序，通过数据报通道使用Java发送和接收序列化对象，但当试图从BufferUnderFlow读取对象时，我收到了一个ObjectInputStream异常。

目前，我有以下代码：

发件人：

public void sendMessage(InetSocketAddress destination) {
    writeBuffer = ByteBuffer.allocate(64000);
    writeBuffer.clear();
    /*
     * Put new MyObject into a ByteArrayOutputStream and put that
     * into the writeBuffer to be sent.
     */
    MyObject myObject = new MyObject();
    byteArrayOS = new ByteArrayOutputStream(writeBuffer.capacity());
    objectOS = new ObjectOutputStream(byteArrayOS);
    objectOS.writeObject(myObject);
    objectOS.flush();

    writeBuffer.put(byteArrayOS.toByteArray());
    writeBuffer.flip();
    channel.send(writeBuffer, new InetSocketAddress(ipAddress, portNum));
    // Channel is bound to correct IP / Port
}

接受者：

public void read() {
  try { //blah blah
    channel = DatagramChannel.open();
    channel.socket().bind(new InetSocketAddress(readPort));
    channel.configureBlocking(true);

    ByteArrayInputStream byteArrayIS = null;
    ObjectInputStream objectIS = null;
    MyObject object;
    while (true) {
        inputBuffer.clear();
    client.getChannel().receive(inputBuffer);
    byte[] data = new byte[inputBuffer.capacity()];
    inputBuffer.get(data);
        /*
         * Troubleshooting: inputBuffer is returning with something
         */
        byteArrayIS = new ByteArrayInputStream(data);
        objectIS = new ObjectInputStream(byteArrayIS);
        myObject = objectIS.readObject(); // Throwing BufferUnderflowException here
        // Process object
        // ...
    }
  } catch (BlahBlah e) {}
}

这是我得到的例外：

Exception in thread "main" java.nio.BufferUnderflowException
        at java.nio.HeapByteBuffer.get(HeapByteBuffer.java:145)
        at java.nio.ByteBuffer.get(ByteBuffer.java:694)
        at package.Class.main(Class.java:493)

是什么导致抛出这个BufferUnderflowException？我搞不懂。两个ByteBuffers都分配了相同的空间，并且writeBuffer没有溢出。

Answer 1

必须翻转()缓冲区才能从缓冲区中获取数据。注意，您应该在该行中使用极限()，而不是容量()。