我希望在SocketChannel
的close
方法被调用时收到通知。我的第一个想法是创建一个包装器,在implCloseSelectableChannel
方法被调用时通知监听器(因为close
方法本身在AbstractInterruptibleChannel
中被声明为final
)。这个解决方案有效,但当我尝试将其与Selector
注册时,会出现IllegalSelectorException
,因为在SelectorImpl
中有以下检查:
/* */ protected final SelectionKey register(AbstractSelectableChannel paramAbstractSelectableChannel, int paramInt, Object paramObject)
/* */ {
/* 128 */ if (!(paramAbstractSelectableChannel instanceof SelChImpl))
/* 129 */ throw new IllegalSelectorException();
现在我无法重写
register
方法以委托给包装的SocketChannel
,因为它在AbstractSelectableChannel
中被声明为final
,而我又无法实现SelChImpl
,因为它在sun.nio.ch
包中具有默认可见性。我唯一能想到的继续进行的方式是制作自己的SelectorProvider
和Selector
,但这似乎对于如此简单的事情来说过于繁琐。是否有更简单的方法来通知我
SocketChannel
何时已关闭,或者我需要重新考虑我的程序设计?
SocketChannelWrapper
示例: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);
}
}
SocketChannel
的人通知我。如果他们不这样做,事情就会开始出错。虽然有点懒惰/健忘,但最简单的方法是在SocketChannel
中直接设置回调函数。如果这个问题继续存在,我可能需要重新考虑我的设计。 - JeffreySocketChannel
的工作方式,以免给自己带来麻烦。 - Jeffreyif (!key.isValid()) continue;
。如果您需要更多内容,我建议您的设计可能存在问题。 - user207421