Question

我不确定关闭我的服务器（和ExecutorService）究竟是什么问题。我启动ServerMain并按Enter键，它启动带有socket.close（）的server.shutdown（）方法，但它不会抛出SocketException。我不知道这是否与ExecutorService无法关闭相关。这是代码：

public class ServerMain {

public static void main(String[] args) throws DirectoryServerException, IOException {
    TCPDirectoryServer server = new TCPDirectoryServer();
    ExecutorService serverExecutor = Executors.newSingleThreadExecutor();
    try {
        server.start(1337);
        serverExecutor.execute(server);
        System.out.println("Server started. Press enter to terminate.");

        System.in.read();

        server.shutdown();
        System.out.println("Server is shut down...");
    } finally {
        serverExecutor.shutdown();
        while (!serverExecutor.isTerminated()) {
            try {
                if (!serverExecutor.awaitTermination(5, TimeUnit.SECONDS)) {
                    System.err.println("Problem with shutting down the Executor");
                    serverExecutor.shutdownNow();
                }
            } catch (InterruptedException ignore) {
            }
        }
    }
}
}

这是服务器：

public class TCPDirectoryServer implements DirectoryServer {
private int port;
private ConcurrentHashMap<ParseDirectory, Histogram> cache;
private List<ClientHandler> clientHandlerList;
private ExecutorService clientExecutorService;
private Socket socket;

public TCPDirectoryServer() {
    super();
    this.cache = new ConcurrentHashMap<ParseDirectory, Histogram>();
    this.clientHandlerList = new LinkedList<ClientHandler>();
    this.clientExecutorService = Executors.newCachedThreadPool();
}

@Override
public void start(int port) throws DirectoryServerException {
    this.port = port;
}

@Override
public void disconnect(ClientHandler clientHandler) {
    clientHandlerList.remove(clientHandler);

}

@Override
public void shutdown() throws DirectoryServerException {
    try {
        socket.close();
    } catch (IOException e) {
        throw new DirectoryServerException(e);
    }
}

@Override
public void run() {
    try (ServerSocket serverSocket = new ServerSocket(port)) {
        while (true) {
            socket = serverSocket.accept();
            clientHandlerList.add(connect(socket));
        }
    } catch (SocketException e) {
        System.err.println("AAAA");
        System.out.println("Server is shutting down");

    } catch (IOException e) {
        System.out.println("Something failed " + e.getMessage());
    }
}

Answer 1

这部分：

    while (true) {
        socket = serverSocket.accept();
        clientHandlerList.add(connect(socket));
    }

...当你调用shutdown时，不会抛出SocketException，因为你正在那里关闭一个客户端套接字（最后连接的那个）。 ServerSocket仍处于打开状态，正在等待传入的请求。

Answer 2

调用serverExecutor.shutdown（）仍然会导致服务器在关闭之前等待所有进程完成。这是一个优雅的关闭。它可能正在等待“while（true）”循环退出，它看起来并不像以往那样。尝试调用serverExecutor.shutdownNow（）;终止你的程序。

Answer 3

在你的TCPDirectoryServer类中，使serverSocket成为一个成员变量，你的shutdown方法应该如下所示

public void shutdown() {
   ......
   this.serverSocket.close();
   ........
}

当关闭客户端套接字时，如果套接字为空（没有人连接到您的服务器），请注意NPE。这也会阻止您的服务器关闭。

Java ExecutorService无法在执行Server时关闭

3 个答案: