java - 如何在 Java 中启动 shell 终端 session 并使用它来放置命令并读取其结果以保持先前的上下文

Question

我有一个必须镜像 Linux shell 的 Web 应用程序，也就是说，用户将有一个模拟 shell 的屏幕，并在服务器端有一个实际的 shell。

我已经实现了一个快速但肮脏的解决方案来测试与 shell Process 的交互，但它似乎不起作用:这是一个简单的 Spring Controller，用户可以在其中传递命令并获得结果:

@RestController
public class ShController{

    @GetMapping("/sh")
    public DeferredResult<String> shSessionCommand(@RequestParam String command) throws IOException, InterruptedException {
        DeferredResult<String> dr = new DeferredResult<>();

        ProcessBuilder pb = new ProcessBuilder("sh");
        //START SHELL
        Process p = pb.start();

        InputStream inputStream = p.getInputStream();
        Thread t = new Thread(() -> {
            //BACKGROUND SHELL OUTPUT READ
            byte[] read = new byte[2048];
            try {
                inputStream.read(read);
                dr.setResult(new String(read));
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
        t.start();
        //TO ALLOW THE SHELL READER TO START BEFORE PASSING THE COMMAND
        Thread.sleep(5000);
        //WRITE THE USER COMMAND
        OutputStream outputStream = p.getOutputStream();
        outputStream.write(command.getBytes());
        outputStream.flush();

        return dr;
    }
}

当我调用 /sh?command=ls outputStream.write(command.getBytes()); 写入 ls 但 inputStream.read(read) 永远被阻塞。为什么？

更新:

说明:

1. 每个用户都需要有自己的shell进程
2. 每个用户 shell session 都将使用很长时间来保持其上下文

我已经更新了 Controller 以反射(reflect)这一点。有一个 map ，我在其中保存用户与其 shell 进程之间的关系。现在，我关闭了 OutputStream，inputStream.read(read); 确实读取了命令结果，但是，只是第一次。后续发出更多命令的调用在调用 outputStream.write(command.getBytes()); 时抛出 java.io.IOException: Stream closed。有什么想法吗？

@RestController
public class ShController{

    private Map<String, Process> shellMap = new HashMap<>();

    @GetMapping("/sh")
    public DeferredResult<String> shSessionCommand(@RequestParam String command, HttpSession session) throws IOException, InterruptedException {
        DeferredResult<String> dr = new DeferredResult<>();

        Process p = getUserShell(session.getId());

        InputStream inputStream = p.getInputStream();
        Thread t = new Thread(() -> {
            System.out.println("****THREAD");
            byte[] read = new byte[2048];
            try {
                inputStream.read(read);
                dr.setResult(new String(read));
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
        t.start();

        Thread.sleep(1000);
        System.out.println("****COMMAND");
        OutputStream outputStream = p.getOutputStream();
        outputStream.write(command.getBytes());
        outputStream.flush();
        outputStream.close();

        return dr;
    }

    private Process getUserShell(String user) throws IOException {
        if(this.shellMap.get(user) == null){
            System.out.println("****Creating process");
            ProcessBuilder pb = new ProcessBuilder("sh");
            Process process = pb.start();
            shellMap.put(user, process);
        }
        return shellMap.get(user);
    }
}

Answer 1

问题是我没有发送新行(输入)字符，就好像我从未提交过命令一样。这是解决方案:

@RestController
public class ShController{

    private Map<String, Process> shellMap = new HashMap<>();

    @GetMapping("/sh")
    public String shSessionCommand(@RequestParam String command, HttpSession session) throws IOException, InterruptedException {

        String result = "";
        Process process = getUserShell(session.getId());
        InputStream out = process.getInputStream();
        OutputStream in = process.getOutputStream();

        byte[] buffer = new byte[4000];
        boolean read = false;
        boolean written = false;
        while (!read) {
            int no = out.available();
            if (no > 0) {
                int n = out.read(buffer, 0, Math.min(no, buffer.length));
                result = new String(buffer, 0, n);
                read = true;
            }

            if(!written) {
                in.write((command + "\n").getBytes());
                in.flush();
                written = true;
            }

            try {
                Thread.sleep(10);
            } catch (InterruptedException e) {
              e.printStackTrace();
            }
        }

        return result;
    }

    private Process getUserShell(String user) throws IOException {
        if(this.shellMap.get(user) == null){
            System.out.println("****Creating process");
            ProcessBuilder pb = new ProcessBuilder("sh", "-i");
            Process process = pb.start();
            shellMap.put(user, process);
        }
        return shellMap.get(user);
    }
}