无法从Java启动程序（使用ProcessBuilder）

Z时代
2024-01-10
分类：问答

我正在尝试从Java应用程序调用cleartool，但是

即使对于简单的“ -version”参数，cleartool也会挂起。运行cleardiff而不是cleartool

可以正常工作，因此显然cleartool

程序有一些特定的东西（我认为这与其交互功能有关）。

以下程序

import java.io.*;
import java.util.*;
public class ExecTesting extends Thread {
    private List<String> command = new ArrayList<String>();
    public ExecTesting (List<String> command) {
        super();
        this.command = command;
    }
    private void print(String s) {
        System.out.println(s);
    }
    @Override
    public void run() {
        Process process;
        OutputStream stdin;
        InputStream stdout;
        InputStream stderr;
        String line;
        try {
            String commandString = joinList(command, " ");
            print("Executing: " + commandString);
            // runtime.exec has several issues (http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html?page=1)
            // better to use ProcessBuilder (http://java.sun.com/developer/JDCTechTips/2005/tt0727.html#2)
            //process = Runtime.getRuntime().exec(commandString);
            process = new ProcessBuilder(command).start();
            // it fails in both cases though
            stdin  = process.getOutputStream();
            stdout = process.getInputStream();
            stderr = process.getErrorStream();
            BufferedReader bufferedStderr = new BufferedReader(new InputStreamReader(stderr));
            while ((line = bufferedStderr.readLine()) != null) {
                print("stderr: " + line);
            }
            bufferedStderr.close();
            BufferedReader bufferedStdout = new BufferedReader(new InputStreamReader(stdout));
            while ((line = bufferedStdout.readLine()) != null) {
                print("stdout: " + line);
            }
            bufferedStdout.close();
            stdin.close();
            stdout.close();
            stderr.close();
            process.waitFor();
            print("Execution finished, exit code " + process.exitValue());
            process.destroy();
        } catch (IOException e) {
            print("IOException: " +e.getStackTrace());
        } catch (InterruptedException e) {
            print("InterruptedException: " + e.getStackTrace());
        }
    }
    /* assumes a list with at least one element */
    private static String joinList(List<String> list, String glue) {
        Iterator<String> i = list.iterator();
        String ret = i.next();
        while (i.hasNext()) {
            ret += glue + i.next();
        }
        return ret;
    }
    public static void main(String[] args) {
        ArrayList<String> cmd1 = new ArrayList<String>();
        cmd1.add("c:\\Program Files\\Rational\\ClearCase\\bin\\cleardiff.exe");
        cmd1.add("-version");
        ExecTesting et1 = new ExecTesting(cmd1);
        et1.start();
        ArrayList<String> cmd2 = new ArrayList<String>();
        //cmd2.add("c:\\Program Files\\Rational\\ClearCase\\bin\\cleardiff.exe");
        cmd2.add("c:\\Program Files\\Rational\\ClearCase\\bin\\cleartool.exe");
        cmd2.add("-version");
        ExecTesting et2 = new ExecTesting(cmd2);
        et2.start();
        et1 = new ExecTesting(cmd1);
        et1.start();
    }
}

gives the following output

Executing: [c:\Program Files\Rational\ClearCase\bin\cleardiff.exe, -version] Executing: [c:\Program Files\Rational\ClearCase\bin\cleartool.exe, -version] Executing: [c:\Program Files\Rational\ClearCase\bin\cleardiff.exe, -version] stdout: cleardiff 2003.06.10+ (Tue Jul 13 14:02:05 2004) Execution finished, exit code 0

hanging on the execution of the cleartool command. If instead cmd2 is changed

to cleardiff the output is as expected

Executing: [c:\Program Files\Rational\ClearCase\bin\cleardiff.exe, -version] Executing: [c:\Program Files\Rational\ClearCase\bin\cleardiff.exe, -version] Executing: [c:\Program Files\Rational\ClearCase\bin\cleardiff.exe, -version] stdout: cleardiff 2003.06.10+ (Tue Jul 13 14:02:05 2004) Execution finished, exit code 0 stdout: cleardiff 2003.06.10+ (Tue Jul 13 14:02:05 2004) Execution finished, exit code 0 stdout: cleardiff 2003.06.10+ (Tue Jul 13 14:02:05 2004) Execution finished, exit code 0

Question: Does anyone know why cleartool is hanging and how to fix?