java - 如何检查套接字的输出流是否关闭？

Question

我有这个代码:

public void post(String message) {
    output.close();
    final String mess = message;
    (new Thread() {
        public void run() {
            while (true) {
                try {
                    output.println(mess);
                    System.out.println("The following message was successfully sent:");
                    System.out.println(mess);
                    break;
                } catch (NullPointerException e) {
                    try {Thread.sleep(1000);} catch (InterruptedException ie) {}
                }
            }
        }
    }).start();
}

如您所见，我在代码的开头关闭了套接字，然后尝试使用它向另一台计算机发送一些信息。该程序写给我“以下消息已成功发送”。这意味着没有抛出 NullPointerException。

那么，如果 Java 尝试使用套接字的封闭输出流，它是否不会抛出异常？有没有办法检查套接字是关闭还是打开？

已添加

我按以下方式初始化套接字:

clientSideSocket = new Socket(hostname,port);
PrintWriter out = new PrintWriter(clientSideSocket.getOutputStream(), true);
browser.output = out;

Answer 1

我应该看起来更好。来自 PrintWriter 的 javadoc:

Methods in this class never throw I/O exceptions, although some of its constructors may. The client may inquire as to whether any errors have occurred by invoking {@link #checkError checkError()}.