我想在SocketChannel
调用close
方法时收到通知。我的第一个想法是创建一个包装,通知聆听者何时调用implCloseSelectableChannel
方法(因为close
方法本身在AbstractInterruptibleChannel
中声明为final
)。该解决方案的工作,但是当我试图用Selector
注册它,我会得到一个IllegalSelectorException
因为SelectorImpl
以下检查:如何在SocketChannel关闭时收到通知?
/* */ protected final SelectionKey register(AbstractSelectableChannel paramAbstractSelectableChannel, int paramInt, Object paramObject)
/* */ {
/* 128 */ if (!(paramAbstractSelectableChannel instanceof SelChImpl))
/* 129 */ throw new IllegalSelectorException();
现在我不能覆盖register
方法来委托给包裹SocketChannel
因为它在AbstractSelectableChannel
中被声明为final
,我无法执行SelChImpl
,因为它在sun.nio.ch
包中具有默认可见性。我可以看到从这里出发的唯一方法是制作我自己的SelectorProvider
和Selector
,但对于如此简单的事情来说,这看起来有点过分。
当SocketChannel
已关闭或者是否需要重新考虑我的程序设计时,是否有更容易通知的方法?
SocketChannelWrapper
例如:
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketOption;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
public class SocketChannelWrapper extends SocketChannel {
private static interface CloseListener {
public void socketChannelClosed(SocketChannel channel);
}
private final SocketChannel socket;
private final CloseListener listener;
public SocketChannelWrapper(SocketChannel socket, CloseListener l) {
super(socket.provider());
this.socket = socket;
listener = l;
}
@Override
public SocketAddress getLocalAddress() throws IOException {
return socket.getLocalAddress();
}
@Override
public <T> T getOption(SocketOption<T> name) throws IOException {
return socket.getOption(name);
}
@Override
public Set<SocketOption<?>> supportedOptions() {
return socket.supportedOptions();
}
@Override
public SocketChannel bind(SocketAddress local) throws IOException {
return socket.bind(local);
}
@Override
public <T> SocketChannel setOption(SocketOption<T> name, T value)
throws IOException {
return socket.setOption(name, value);
}
@Override
public SocketChannel shutdownInput() throws IOException {
return socket.shutdownInput();
}
@Override
public SocketChannel shutdownOutput() throws IOException {
return socket.shutdownOutput();
}
@Override
public Socket socket() {
return socket.socket();
}
@Override
public boolean isConnected() {
return socket.isConnected();
}
@Override
public boolean isConnectionPending() {
return socket.isConnectionPending();
}
@Override
public boolean connect(SocketAddress remote) throws IOException {
return socket.connect(remote);
}
@Override
public boolean finishConnect() throws IOException {
return socket.finishConnect();
}
@Override
public SocketAddress getRemoteAddress() throws IOException {
return socket.getRemoteAddress();
}
@Override
public int read(ByteBuffer dst) throws IOException {
return socket.read(dst);
}
@Override
public long read(ByteBuffer[] dsts, int offset, int length)
throws IOException {
return socket.read(dsts, offset, length);
}
@Override
public int write(ByteBuffer src) throws IOException {
return socket.write(src);
}
@Override
public long write(ByteBuffer[] srcs, int offset, int length)
throws IOException {
return socket.write(srcs, offset, length);
}
@Override
protected void implCloseSelectableChannel() throws IOException {
socket.close();
listener.socketChannelClosed(this);
}
@Override
protected void implConfigureBlocking(boolean block) throws IOException {
socket.configureBlocking(block);
}
public static void main(String[] args) throws UnknownHostException,
IOException {
final Selector selector = Selector.open();
Thread t = new Thread(new Runnable() {
@Override
public void run() {
while (true) {
try {
selector.select();
Iterator<SelectionKey> itr = selector.selectedKeys()
.iterator();
while (itr.hasNext()) {
SelectionKey key = itr.next();
itr.remove();
if (key.isValid()) {
if (key.isAcceptable()) {
((ServerSocketChannel) key.channel())
.accept();
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
});
t.setDaemon(true);
ServerSocketChannel server = ServerSocketChannel.open().bind(
new InetSocketAddress(1234));
server.configureBlocking(false);
server.register(selector, SelectionKey.OP_ACCEPT);
t.start();
SocketChannel socket = new SocketChannelWrapper(
SocketChannel.open(new InetSocketAddress(InetAddress
.getLocalHost(), 1234)), new CloseListener() {
@Override
public void socketChannelClosed(SocketChannel channel) {
System.out.println("Socket closed!");
}
});
socket.configureBlocking(false);
// socket.close(); //prints out "Socket closed!"
socket.register(selector, SelectionKey.OP_READ);
}
}
问题是,如果我的程序要正常工作,我需要关闭'SocketChannel'的任何人来通知我。如果他们不这样做,事情就会破裂。打电话给我懒/健忘,但最简单的方法就是在SocketChannel中直接调用回调函数。如果这仍然是一个问题,我可能需要重新考虑我的设计。 – Jeffrey 2012-02-27 22:57:33
@Jeffrey你需要调试你的应用程序。 – EJP 2012-02-28 00:22:22
我的应用程序中没有错误,但是如果我忘记通知自己弹出一个错误。到目前为止,我已经知道了这个问题,有一个“doh”时刻,然后继续前进,但是这些日子里我会忘记通知自己,我无法弄清楚为什么。我想看看我是否可以修改'SocketChannel'的工作方式以节省一些麻烦。 – Jeffrey 2012-02-28 00:31:21