Java服务器程序仅在本地主机上工作，而在客户端从另一台计算机连接时不工作

嗨，这里有人问了一个类似的问题： 然而，我有一个不同的错误。我是java的新手，正在阅读oracle的教程代码，尝试学习如何设置客户机/服务器

/*
 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

import java.io.*;
import java.net.*;

public class KnockKnockClient {
    public static void main(String[] args) throws IOException {

        if (args.length != 2) {
            System.err.println(
                "Usage: java EchoClient <host name> <port number>");
            System.exit(1);
        }

        String hostName = args[0];
        int portNumber = Integer.parseInt(args[1]);

        try (
            Socket kkSocket = new Socket(hostName, portNumber);
            PrintWriter out = new PrintWriter(kkSocket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(
                new InputStreamReader(kkSocket.getInputStream()));
        ) {
            BufferedReader stdIn =
                new BufferedReader(new InputStreamReader(System.in));
            String fromServer;
            String fromUser;

            while ((fromServer = in.readLine()) != null) {
                System.out.println("Server: " + fromServer);
                if (fromServer.equals("Bye."))
                    break;

                fromUser = stdIn.readLine();
                if (fromUser != null) {
                    System.out.println("Client: " + fromUser);
                    out.println(fromUser);
                }
            }
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host " + hostName);
            System.exit(1);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to " +
                hostName);
            System.exit(1);
        }
    }
}

/*
 * Copyright (c) 1995, 2014, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

import java.net.*;
import java.io.*;

public class KnockKnockServer {
    public static void main(String[] args) throws IOException {

        if (args.length != 1) {
            System.err.println("Usage: java KnockKnockServer <port number>");
            System.exit(1);
        }

        int portNumber = Integer.parseInt(args[0]);

        try ( 
            ServerSocket serverSocket = new ServerSocket(portNumber);
            Socket clientSocket = serverSocket.accept();
            PrintWriter out =
                new PrintWriter(clientSocket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(
                new InputStreamReader(clientSocket.getInputStream()));
        ) {

            String inputLine, outputLine;

            // Initiate conversation with client
            KnockKnockProtocol kkp = new KnockKnockProtocol();
            outputLine = kkp.processInput(null);
            out.println(outputLine);

            while ((inputLine = in.readLine()) != null) {
                outputLine = kkp.processInput(inputLine);
                out.println(outputLine);
                if (outputLine.equals("Bye."))
                    break;
            }
        } catch (IOException e) {
            System.out.println("Exception caught when trying to listen on port "
                + portNumber + " or listening for a connection");
            System.out.println(e.getMessage());
        }
    }
}

在“java KnockKnockClient localhost 4444”行上，它设置主机和端口#。localhost或127.0.0.1可以工作，但如果我将其替换为我的IP地址，则会出现以下错误： 无法获取连接到[我的IP地址]的I/O

我试着在关闭防火墙的情况下做这件事，但没有成功。我真正想做的是将KnockKnockServer程序放在我的家用计算机上，将knockclient程序放在任何其他计算机上，并且能够使用客户端程序连接到服务器，无论其他计算机在哪里。我做错了什么？谢谢

我添加了printStackTrace（）：

java.net.ConnectException:连接超时：连接
位于java.net.DualStackPlainSocketImpl.connect0（本机方法）
位于java.net.DualStackPlainSocketImpl.socketConnect（未知源）
位于java.net.AbstractPlainSocketImpl.doConnect（未知源）
位于java.net.AbstractPlainSocketImpl.connectToAddress（未知源）
位于java.net.AbstractPlainSocketImpl.connect（未知源）
位于java.net.PlainSocketImpl.connect（未知源）
位于java.net.socksocketimpl.connect（未知源）
位于java.net.Socket.connect（未知源）
位于java.net.Socket.connect（未知源）
位于java.net.Socket。（未知源）
位于java.net.Socket。（未知源）
位于knockclient.main（knockclient.java:48）

---

我猜这意味着没有建立连接。我尝试打开路由器设置上的端口，但仍然无法工作。我有一个cisco Linksys E2000路由器，可能是因为它不允许打开这些端口吗？

看看KnockClient类的最后几行。它正在打印该错误，因为您发布的代码告诉它在出现异常时打印该错误。添加一行以打印出异常，以便获得更多信息。像这样：

} catch (IOException e) {
  System.err.println("Couldn't get I/O for the connection to " + hostName);
  e.printStackTrace();
  System.exit(1);
}

---

可能您正在使用路由器，如果是，请确保您有开放的端口。取决于路由器的型号，方法有所不同，但通常必须进入路由器的配置（192.168.1.1）->虚拟服务器，您添加了ip和端口以释放。

您是否尝试了链接帖子中答案中的步骤？您忽略了/*默默地吃着*，这告诉您到底出了什么问题<代码>e.printStackTrace（）会准确地告诉您出了什么问题。更改无用的错误消息以打印实际的异常。几年前我向Sun抱怨在他们的教程中使用了那些愚蠢的错误信息。我想他们终于解决了其中的一些问题。显然不是全部。@JarrodRoberson复制品的选择非常差。他引用自己的例子是一个更好的选择：我知道这很古老，但我想用我的解决方案，以防它对其他人有帮助。我试图通过本地连接从笔记本电脑连接到台式电脑。问题是，我的路由器中有单独的无线和有线连接交换机，导致笔记本电脑无法连接到桌面，因为它们实际上位于单独的本地网络上。所以，我对它进行了测试，笔记本电脑或台式机连接工作正常。希望有帮助。我添加了端口转发并输入了本地ip地址，但它不起作用。我去看了看端口是否打开并且没有骰子

java.net.ConnectException: Connection timed out: connect
        at java.net.DualStackPlainSocketImpl.connect0(Native Method)
        at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
        at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
        at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
        at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
        at java.net.PlainSocketImpl.connect(Unknown Source)
        at java.net.SocksSocketImpl.connect(Unknown Source)
        at java.net.Socket.connect(Unknown Source)
        at java.net.Socket.connect(Unknown Source)
        at java.net.Socket.<init>(Unknown Source)
        at java.net.Socket.<init>(Unknown Source)
        at KnockKnockClient.main(knockknockclient.java:48)

} catch (IOException e) {
  System.err.println("Couldn't get I/O for the connection to " + hostName);
  e.printStackTrace();
  System.exit(1);
}