Question

很抱歉问题，但我完全是Java中的noob。从ServerSocket.close()抓获IOException时执行ServerSocket的最佳做法是什么？根据文档，ServerSocket.close()抛出IOException，编译器要求我们抓住它。在IOException上关闭连接的正确方法是什么？

try {
    server = new ServerSocket(this.getServerPort());
    while(true) {
        socket = server.accept();
        new Handler( socket );
    }
} catch (IOException e) {
    if (server != null && !server.isClosed()) {
        server.close(); //compiler do not allow me to do because I should catch IOExceoption from this method also...
    }
}

谢谢！

Answer 1

如果你打算在try {} catch {}之外关闭ServerSocket，你也可以把它放在finally {}

中。

try {
    server = new ServerSocket(this.getServerPort());
    while(true) {
        socket = server.accept();
        new Handler( socket );
    }
} catch (IOException e) {
    // Do whatever you need to do here, like maybe deal with "socket"?
}
finally {
    try {  
        server.close();
    } catch(Exception e) {
        // If you really want to know why you can't close the ServerSocket, like whether it's null or not
    }
}

Answer 2

Java中的丑陋。我讨厌它，但这是你应该这样做的方式：把它包装成另一个try-catch：

try {
    server = new ServerSocket(this.getServerPort());
    while(true) {
        socket = server.accept();
        new Handler( socket );
    }
} catch (IOException e) {
    if (server != null && !server.isClosed()) {
        try {
            server.close();
        } catch (IOException e)
        {
            e.printStackTrace(System.err);
        }
    }
}

Answer 3

在Java SE 7或更高版本中，您可以使用try-with-resources statement，ServerSocket implements java.io.Closeable，因此在以这种方式使用时，您无需显式#close()套接字。

try (ServerSocket server = new ServerSocket(this.getServerPort())) {
    while(true) {
        socket = server.accept();
        new Handler( socket );
    }
} catch (IOException e) {
    // It's already closed, just print the exception
    System.out.println(e);
}

Answer 4

您可以关闭finally块中的资源

http://download.oracle.com/javase/tutorial/essential/exceptions/finally.html

 } finally {
      try {
        socket.close();
      } catch(IOException e) {
         e.printStackTrace(); 
      }
}

如何在捕获IOException时关闭ServerSocket连接？

4 个答案: