在Java中创建一个新进程，退出当前进程 [英] Create a new process in Java, exit the current process

问题描述

在我的代码中，我想重新启动程序.为此，我在 Windows 中使用了以下代码:

In my code, I want to restart the program. For this i have used the following code in Windows:

if(System.getProperty("os.name").contains("Windows"))
{
    //For Windows Builds use this
    new ProcessBuilder("java", "Launcher").inheritIO().start();
    System.exit(0);
}

对于我使用的 Linux 构建

For Linux Builds I used

else
{
    //For Linux/Unix or Mac Builds use this
    new ProcessBuilder("/bin/bash", "-c" ,"java Launcher").inheritIO().start();
}

现在，Windows 的实现工作得很好.它开始一个新实例并退出旧实例.但是 Linux 的实现有点奇怪.我添加了 System.exit(0); 认为它会在创建新进程后立即终止当前进程，但它似乎退出了进程本身.我无法在 Linux 中以任何方式重新启动该程序，尽管它在 Windows 中是可行的.

So now, the implementation for Windows works just fine. It begins a new instance and exits the old. But the Linux implementation is kinda a bit odd. I added System.exit(0); thinking that it will kill the current process right after creating the new one, but it seemed to exit the process itself. I cannot restart the program in anyway in Linux, although it was doable in Windows.

希望得到帮助和反馈！

[2020 年 7 月 28 日]

[28-July-2020]

所以我确实发现新进程创建了，但是IO没有继承到新会话.我调整了一些代码，现在程序创建了新进程，获得了 IO 控制，并在输入命令后退出.

So I did find that the new process is created, but the IO is not inherited to the new session. I tweaked a bit of code and now the program creates the new process, gets IO control and after entering a command, it exits.

if(System.getProperty("os.name").contains("Windows"))
{
    //For Windows Builds use this
    new ProcessBuilder("cmd", "/c", "java Launcher").inheritIO().start();
    System.exit(0);
}
else
{
    //For Linux/Unix or Mac Builds use this
    long pid = ProcessHandle.current().pid();
    System.out.println(pid);
    String a=String.valueOf(pid);
    Thread.sleep(10000);
    System.out.println(new ProcessBuilder("/bin/bash", "-c", "java Launcher").inheritIO().start());
    System.exit(1);
}

没有 System.exit(1); 程序继续使用新创建的进程，但旧进程仍在后台运行.当我试图杀死旧进程时，两个进程都被杀死了.

Without System.exit(1); the program continues with the newly created process, but with the old process still running in the background. When I try to kill the old process, both the processes are killed.

这是新的屏幕截图，上面指定了代码.https://gofile.io/d/MAYLeJ

Here are the new screenshots, with the code specified above. https://gofile.io/d/MAYLeJ

[2020 年 7 月 29 日]

[29-July-2020]

一直在研究代码为何不起作用.我确实收到了 WSL 未检测到的相同代码的异常！

Been working more on why the code is not working. I did get an exception for the same code, which WSL didnt detect!

错误日志

推荐答案

更新:我确实找到了正确的答案，可能有点复杂，但我会尽量简化.

Update: I did find the right answer and it might be a bit complex, but I shall try to make it as simple as possible.

在这里，我们将需要 2 个单独的类:1 个类用于监视子进程，1 个类是主进程.

In this, we will require 2 separate classes: 1 class to monitor the child process, 1 class which is the main process.

为了简单起见，我将监控类命名为SessionManager，主类命名为mainClass

For the sake of simplicity, I shall name the monitoring class as SessionManager and the main class as mainClass

在 SessionManager 类中，我实现了以下代码.

In the SessionManager class, I've implemented the following code.

try
{
    //A loop which will run infinitely to montior and start new processes
    while(true)
    {
        //Create the process and listen to the exit code generated by the child process spawned.
        ProcessBuilder session_monitor=new ProcessBuilder("java", "<classname>");
        Process process_monitor= session_monitor.inheritIO().start();
    
        //wait for the child process to end before proceeding
        process_monitor.waitFor();
                
        switch(process_monitor.exitValue())
        {
            //Implement the logic here
            case 0: //do something
            break;

            case 1: //do something
            break;
        }
    }
}
catch(Exception E)
{
    E.printStackTrace();
}

在mainClass程序中，我们将有一个main方法来启动进程运行.

And in the mainClass program, we shall have a main method to start the process running.

class mainClass
{
    System.out.println("Hello World");
    //exit the process with a code for the SessionManager's logic to work
    System.exit(0);          //Using a normal exit code here
}

这对我有用，如果您认为可以改进此实现，我很乐意听到.谢谢大家的支持:)

This has worked for me, and if you think this implementation can be improved, I'd love to hear it. Thank you for all your support :)

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