Question

为什么我会收到取消键异常的错误？谁能帮帮我吗？客户代码的哪一部分出了问题？

java.nio.channels.CancelledKeyException
at sun.nio.ch.SelectionKeyImpl.ensureValid(SelectionKeyImpl.java:73)
at sun.nio.ch.SelectionKeyImpl.interestOps(SelectionKeyImpl.java:82)
at viaNIO.clientasync2.write(clientasync2.java:130)
at viaNIO.clientasync2.run(clientasync2.java:53)
at java.lang.Thread.run(Thread.java:745)

java.nio.channels.CancelledKeyException
at sun.nio.ch.SelectionKeyImpl.ensureValid(SelectionKeyImpl.java:73)
at sun.nio.ch.SelectionKeyImpl.readyOps(SelectionKeyImpl.java:87)
at java.nio.channels.SelectionKey.isReadable(SelectionKey.java:289)
at viaNIO.clientasync2.run(clientasync2.java:55)
at java.lang.Thread.run(Thread.java:745)

以下是客户的代码：

        while (!Thread.interrupted()) {

            selector.select();

            Iterator<SelectionKey> keys = selector.selectedKeys().iterator();

            while (keys.hasNext()) {
                SelectionKey key = keys.next();
                keys.remove();

                if (key.isValid()) {
                    if (key.isConnectable()) {
                        System.out.println("Connected to the server");
                        connect(key);
                    }
                    if (key.isWritable()) {
                        System.out.println("Writing to the server");
                        write(key);
                    }
                    if (key.isReadable()) {
                        System.out.println("Reading from the server");
                        read(key);
                    }
                }
            }
        }

以下是更新的代码：

   while (!Thread.interrupted()) {

            selector.select();

            Iterator<SelectionKey> keys = selector.selectedKeys().iterator();

            while (keys.hasNext()) {
                SelectionKey key = keys.next();
                keys.remove();

                if (key.isValid() && key.isConnectable()) {
                    connect(key);
                } else {
                    if (key.isValid() && key.isWritable()) {
                        System.out.println("Writing to the server");
                        write(key);
                    }
                    if (key.isValid() && key.isReadable()) {
                        System.out.println("Reading from the server");
                        read(key);
                    }
                }
            }
        }

这也是我写入方法的代码

 private void write(SelectionKey key) throws IOException {
    SocketChannel socket = (SocketChannel) key.channel();
    RandomAccessFile aFile = null;
    try {
        File f = new File("D:/test.rar");
        aFile = new RandomAccessFile(f, "r");
        ByteBuffer buffer = ByteBuffer.allocate(300000000);

        FileChannel inChannel = aFile.getChannel();
        while (inChannel.read(buffer) > 0) {
            buffer.flip();
            socket.write(buffer);
            buffer.clear();
        }
        aFile.close();
        socket.close();
        inChannel.close();
        Thread.sleep(1000);

        key.interestOps(SelectionKey.OP_READ);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

读取方法的代码

  private void read(SelectionKey key) throws IOException {
    SocketChannel channel = (SocketChannel) key.channel();
    ByteBuffer readBuffer = ByteBuffer.allocate(1000);
    readBuffer.clear();
    int length;
    try {
        length = channel.read(readBuffer);
    } catch (IOException e) {
        System.out.println("Reading problem, closing connection");
        key.cancel();
        channel.close();
        return;
    }
    if (length == -1) {
        System.out.println("Nothing was read from server");
        channel.close();
        key.cancel();
        return;
    }
    readBuffer.flip();
    byte[] buff = new byte[1024];
    readBuffer.get(buff, 0, length);
    System.out.println("Server said: " + new String(buff));
    if (readCnt != 1) {
        key.interestOps(SelectionKey.OP_WRITE);
        readCnt++;
    } else {
        key.cancel();
        close();
    }
}

connect方法的代码

 private void connect(SelectionKey key) throws IOException {
    SocketChannel channel = (SocketChannel) key.channel();
    if (channel.isConnectionPending()) {
        channel.finishConnect();
    }
    channel.configureBlocking(false);
    channel.register(selector, SelectionKey.OP_READ);
}

Answer 1

因为connect()或write()在进入isReadable()测试之前关闭了频道或取消了密钥。您需要不断重新测试isValid()。在else块之后还需要isConnectable()，因为OP_CONNECT无法与OP_WRITE或OP_READ一起触发：

if (key.isValid() && key.isConnectable()) {
    System.out.println("Connected to the server"); // see below
    connect(key);
} else {
    if (key.isValid() && key.isWritable()) {
        System.out.println("Writing to the server");
        write(key);
    }
    if (key.isValid() && key.isReadable()) {
        System.out.println("Reading from the server");
        read(key);
    }
}

此消息"Connected to the server"也在错误的位置。您即将尝试来完成连接：当且仅当 finishConnect()返回true时才实际连接。

为什么我会得到CancelledKeyException？

1 个答案: