Question

如何在服务器端检查客户端是否关闭了套接字？

我有这个服务器，等待连接，然后向客户端返回10条消息：

public class SocketServidor {
    static ServerSocket serverSocket;

    public static void main(String[] args) throws Exception {
        serverSocket = new ServerSocket(5963);
        while(true) {
            final Socket socket = serverSocket.accept();
            new Thread(() -> {
                try {
                    PrintWriter out = new PrintWriter(socket.getOutputStream());
                    for (int i = 0; i < 10; i++) {
                        int valor = (int) (Math.random() * 5) + 1;
                        out.println("Você acabou de ganhar R$ "+new DecimalFormat("###,##0.00").format(valor)+"!");
                        out.flush();
                        Thread.sleep(valor*1000);
                    }
                    socket.close();
                } catch (Exception ex) {
                    Logger.getLogger(SocketServidor.class.getName()).log(Level.SEVERE, null, ex);
                }
            }).start();
        }
    }
}

客户端只读取值，但在第五次读取时停止：

public class SocketCliente {

    public static void main(String[] args) throws Exception {
        Socket socket = new Socket("localhost", 5963);
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        String leitura;
        int lidas = 0;
        while((leitura = in.readLine()) != null) {
            lidas++;
            System.out.println(leitura);
            if(lidas == 5){
                socket.close();
            }
        }
    }

}

问题是，当客户端关闭套接字时，即使在第五次读取之后，服务器也会不断向客户端发送消息。如何在客户端关闭服务器端的套接字时将其关闭？

Answer 1

PrintWriter.flush（）
禁止异常您没有看到任何异常，因为PrintWriter.flush（）会禁止该异常。要在PrintWriter.println()之后检查错误状态，您可以使用PrintWriter.checkError()代替flush()。或者，您可以使用OutputStreamWriter而不是PrintWriter，然后不会禁止该异常。

使用checkError

serverSocket = new ServerSocket(5963);
while(true) {
    final Socket socket = serverSocket.accept();
    new Thread(() -> {
        try {
            PrintWriter out = new PrintWriter(socket.getOutputStream());
            for (int i = 0; i < 10; i++) {
                int valor = (int) (Math.random() * 5) + 1;
                out.println("Você acabou de ganhar R$ "+new DecimalFormat("###,##0.00").format(valor)+"!");
                //out.flush();
                if(out.checkError()){
                    System.out.println("Error. Break");
                    break;
                }
                Thread.sleep(valor*1000);
            }
            socket.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }).start();
}

使用OutputStreamWriter

serverSocket = new ServerSocket(5963);
while(true) {
    final Socket socket = serverSocket.accept();
    new Thread(() -> {
        try {
            Writer out = new OutputStreamWriter(socket.getOutputStream());
            for (int i = 0; i < 10; i++) {
                int valor = (int) (Math.random() * 5) + 1;
                out.write("Você acabou de ganhar R$ "+new DecimalFormat("###,##0.00").format(valor)+"!");
                out.write("\r\n");
                out.flush();
                Thread.sleep(valor*1000);
            }
            socket.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }).start();
}

检查服务器上的客户端套接字是否已关闭

1 个答案: