Java动态查找局域网内其他主机

发布于 2024-09-06 06:56:08 字数 1414 浏览 9 评论 0原文

不久前，我开发了一个小型局域网聊天应用程序。在 Java 中，它允许与其他主机聊天、发送图像等。虽然它只是为了好玩而创建的，但现在它已经在我工作的地方使用了。

目前，应用程序上没有“聊天服务器”。每个客户端注册、更新其状态等（我喜欢对称设计的想法，而不是依赖于在其他机器上运行的服务器）。

相反，每个主机都是一个客户端/服务器，它有一个 hosts.properties 文件，其中包含其他主机的主机名，并且 - 例如 - 在发送大量消息/图像/时向每个主机广播任何。

一开始只有几个主机，因此这个 hosts.properties 文件不是问题。但随着用户数量的增加，更新该文件的需求有点令人畏惧。所以现在我决定摆脱它，每次都摆脱这个应用程序。启动后，动态查找其他活动主机。

但是，我找不到实现此目的的正确方法。我尝试启动不同的线程，每个线程都在已知的 IP 地址范围内搜索其他主机。像这样的东西（为了可读性而简化）：

/** HostsLocator */
public static void searchForHosts(boolean waitToEnd) {
    for (int i=0; i < MAX_IP; i+= MAX_IP / threads) {
        HostsLocator detector = new HostsLocator(i, i+(MAX_IP / threads - 1)); // range: from - to
        new Thread(detector).start();                 
    }
}

public void run() {
    for (int i=from; i<=to; i++)
        findHosts( maskAddress + Integer.toString(i) );
}

public static boolean findHosts(String IP) {
    InetAddress address = InetAddress.getByName(IP);
    if ( address.isReachable(CONNECTION_TIME_OUT) )
        // host found!
}

但是：

使用单个线程和 CONNECTION_TIME_OUT 值较低（500ms）时，我得到错误的 Host Not Found 状态 for主机实际活跃。
CONNECTION_TIME_OUT 值较高（5000 毫秒），并且只有一个线程需要永远结束。
对于多个线程，我也发现了与第一个线程类似的问题，原因是冲突。

所以......我想有一个更好的方法来解决这个问题，但我找不到它。有什么建议吗？谢谢！

原文

A while ago I developed a little LAN chat app. in Java which allows chatting with other hosts, send images, etc. Although it was created just for fun, now it's being used where I work.

Currently, there is no "chat server" on the app. where each client registers, updates it's status, etc. (I liked the idea of symmetric design and not depending on a server running on some other machine).

Instead, each host is a client/server which has a hosts.properties file with the hostname of the other hosts, and - for instance - broadcasts to each one of them when sending a massive message/image/whatever.

In the beginning there were just a couple of hosts, so this hosts.properties file wasn't an issue. But as the amount of users increased, the need of updating that file was a bit daunting. So now I've decided to get rid of it, and each time the app. starts, dynammically find the other active hosts.

However, I cannot find the correct way of implement this. I've tried starting different threads, each one of them searching for other hosts in a known range of IP addresses. Something like this (simplified for the sake of readability):

/** HostsLocator */
public static void searchForHosts(boolean waitToEnd) {
    for (int i=0; i < MAX_IP; i+= MAX_IP / threads) {
        HostsLocator detector = new HostsLocator(i, i+(MAX_IP / threads - 1)); // range: from - to
        new Thread(detector).start();                 
    }
}

public void run() {
    for (int i=from; i<=to; i++)
        findHosts( maskAddress + Integer.toString(i) );
}

public static boolean findHosts(String IP) {
    InetAddress address = InetAddress.getByName(IP);
    if ( address.isReachable(CONNECTION_TIME_OUT) )
        // host found!
}

However:

With a single thread and a low value in CONNECTION_TIME_OUT (500ms) I get wrong Host Not Found status for for hosts actually active.
With a high value in CONNECTION_TIME_OUT (5000ms) and only one single thread takes forever to end
With several threads I've also found problems similar like the first one, due to collisions.

So... I guess there's a better way of solving this problem but I couldn't find it. Any advice? Thanks!

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败给现实 2024-09-13 06:56:08

您可以尝试向特定端口进行 UDP 广播。网络上应用程序的所有正在运行的实例都可以侦听该端口，然后使用将其标识为主机的消息进行响应。

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心的位置 2024-09-13 06:56:08

您可以使用 UDP 更轻松地完成此操作。查看本教程以获取示例。

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与他有关 2024-09-13 06:56:08

使用 Bonjour/Zeroconf。

jmdns 项目拥有您所需的一切。

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无可置疑 2024-09-13 06:56:08

要在java中查找局域网中的所有主机，请执行java中的命令并将结果添加到JList

下面是一些小代码，将帮助您在Windows中读取局域网中的所有主机，还有其他命令用于其他os看看下面的代码

try {

    Runtime rt = Runtime.getRuntime();
    FileWriter write=new FileWriter("mylist.txt");
    BufferedWriter writer=new BufferedWriter(write);
    Process pr = rt.exec("net view");

    BufferedReader input = new BufferedReader(new InputStreamReader(pr.getInputStream()));

    String line=null;
    String hosts="";
    while((line=input.readLine()) != null) {
        Thread.sleep(100);
        if((!(line.equals("")))&&(!(line.equalsIgnoreCase("Server Name            Remark")))&&(!(line.equalsIgnoreCase("-------------------------------------------------------------------------------")))&&(!(line.equalsIgnoreCase("The command completed successfully.")))) 
        {
            line=line.replace('\\',' ');
            line=line.trim();
            listModel.addElement(line);
            hosts=hosts+line.trim()+",";
            hosts=hosts.trim();
        }
    }
    writer.write(hosts);
    writer.close();
    } catch(Exception e) {
        System.out.println(e.toString());
        e.printStackTrace();
    }

For finding all hosts in lan in java execute commands from java and add the result to JList

Here is the small code that will help to you to read all hosts in lan in windows there will be other commands for other os take look at the following code

try {

    Runtime rt = Runtime.getRuntime();
    FileWriter write=new FileWriter("mylist.txt");
    BufferedWriter writer=new BufferedWriter(write);
    Process pr = rt.exec("net view");

    BufferedReader input = new BufferedReader(new InputStreamReader(pr.getInputStream()));

    String line=null;
    String hosts="";
    while((line=input.readLine()) != null) {
        Thread.sleep(100);
        if((!(line.equals("")))&&(!(line.equalsIgnoreCase("Server Name            Remark")))&&(!(line.equalsIgnoreCase("-------------------------------------------------------------------------------")))&&(!(line.equalsIgnoreCase("The command completed successfully.")))) 
        {
            line=line.replace('\\',' ');
            line=line.trim();
            listModel.addElement(line);
            hosts=hosts+line.trim()+",";
            hosts=hosts.trim();
        }
    }
    writer.write(hosts);
    writer.close();
    } catch(Exception e) {
        System.out.println(e.toString());
        e.printStackTrace();
    }

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