Question

我使用StreamGobbler读取外部程序的输出。之前我曾经从ffmpeg的stderr读取和解析大（20-40个字符串）输出。现在我想从stdout中读取并解析一个字符串（一个字符串是程序的所有输出，并且该程序非常快地结束）的识别（ImageMagick）。有时它可以工作，但有时我有错误“流关闭”。我认为StreamGobbler没有时间处理流（流程在streamGobler做一些工作之前结束）。

下面你可以看到类ExecThread及其使用示例。

抱歉我的英文...

    String command =  ffmpegExe.getAbsolutePath()+ " -i \""+ fileName +"\"";
    ExecThread thread = new ExecThread(command);
    thread.setPriority(ExecThread.MIN_PRIORITY);
    thread.start();
    thread.waitFor(DEFAULT_WAIT);

    //reading ffmpeg stderr
    BufferedReader ffmpegErr = thread.getErrBufferedReader();
    String line;

    try
    {
        while((line = ffmpegErr.readLine()) !=null)
//some code



private static class ExecThread extends  Thread
{
    public ExecThread(String command)
    {
        this.command = command;
    }
    @Override
    public void run()
    {

        try
        {
            ExecCommand(command);
            exitVal = process.waitFor();
        }
        catch (Exception e )
        {
            logger.error("Error while executing command: " + command + e.getMessage(),e);
            System.err.println("Error");
            System.exit(1);
        }
    }
    public void waitFor(long millis)
    {
        try
        {
            this.join(millis);
            process.destroy();
        } catch (Exception e)
        {
            logger.error("Error while interupting command: " + command + e.getMessage(), e);
        }

    }


    private  void ExecCommand(String command) throws IOException
    {
        //run command
        Runtime rt = Runtime.getRuntime();
        process = rt.exec(new String[]{shellName,shellOption, command}, null, null);

        //get stderr buffered reader
        StreamGobbler errGobbler = new StreamGobbler(process.getErrorStream());
        StreamGobbler outGobbler = new StreamGobbler(process.getInputStream());

        ErrBufferedReader = new BufferedReader(new InputStreamReader(errGobbler));
        OutBufferedReader = new BufferedReader(new InputStreamReader(outGobbler));

    }
    private BufferedReader ErrBufferedReader;

    public BufferedReader getOutBufferedReader()
    {
        return OutBufferedReader;
    }

    private BufferedReader OutBufferedReader;
    private Process process;
    private String command;
    private int exitVal=-1;

    public BufferedReader getErrBufferedReader()
    {
        return ErrBufferedReader;
    }

    public Process getProcess()
    {
        return process;
    }

    public String getCommand()
    {
        return command;
    }

    public int getExitVal()
    {
        return exitVal;
    }
}

Answer 1

我建议进行两项修改：

使用Java Process代替编写主题。
关闭输入，输出和错误流并销毁进程。如果不这样做，你将有文件句柄泄漏。

Answer 2

这不是一个好的决定，但它确实有效。之前String command = identifyExe.getAbsolutePath() + " \"" + file.getAbsolutePath() + "\""; 现在它String command = "sleep 1 ; " + identifyExe.getAbsolutePath() + " \"" + file.getAbsolutePath() + "\"";

睡眠是非常有用的功能： - ）

但是，如果您知道更好的决定，请告诉......

StreamGobbler短输出或非常快速的过程

2 个答案: