Question

I am reading the output of a java application started using Process and reading stdError, stdOutout and using stdInput to send commands. Here is the relevant code:

        int mem = Properties.Settings.Default.mem_max;
        string locale = Properties.Settings.Default.location;
        Process bukkit_jva = new Process();
        bukkit_jva.StartInfo.FileName = "java";
        //bukkit_jva.StartInfo.Arguments = "-Xmx" + mem + "M -Xms" + mem + "M -jar " + locale + "bukkit.jar";
        bukkit_jva.StartInfo.Arguments = "-Xmx512M -Xms512M -jar C:\\bukkit\\bukkit.jar";
        bukkit_jva.StartInfo.UseShellExecute = false;
        bukkit_jva.StartInfo.CreateNoWindow = true;
        bukkit_jva.StartInfo.RedirectStandardError = true;
        bukkit_jva.StartInfo.RedirectStandardOutput = true;
        bukkit_jva.StartInfo.RedirectStandardInput = true;
        bukkit_jva.Start();
        //start reading output
        SetText(bukkit_jva.StandardOutput.ReadLine());
        SetText(bukkit_jva.StandardOutput.ReadLine());
        SetText(bukkit_jva.StandardOutput.ReadLine());
        SetText(bukkit_jva.StandardOutput.ReadLine());
        StreamReader err = bukkit_jva.StandardError;
        StreamReader output = bukkit_jva.StandardOutput;
        StreamWriter writer = bukkit_jva.StandardInput;
        SetText(err.Peek().ToString());
        while (false == false)
        {
            if (vars.input != null)
            {
                writer.WriteLine(vars.input);
                vars.input = null;
            }
            SetText(output.ReadLine() + err.ReadLine());
        }
    }

SetText() adds the line to a list of lines.

My problem is that the java app sometimes returns a string even when there is no input, so I always need to check for a new line. but If I need to send a command, and there is no new output, It will not send.

I tried different If statements on the readline, but it would only return the first few lines then it would stop.

basicly it seems to pause the loop if there is no new line for it to read.

How could I either setup my read/write loop differently or get the loop to unpause?

Thanks,
Adam

Answer 1

try this:

static void Main(string[] args)
{
    ProcessStartInfo psi = new ProcessStartInfo("echoApp.exe");
    psi.RedirectStandardInput = true;
    psi.RedirectStandardOutput = true;
    psi.RedirectStandardError = true;
    psi.UseShellExecute = false;

    Process echoApp = new Process();
    echoApp.ErrorDataReceived += new DataReceivedEventHandler(echoApp_ErrorDataReceived);
    echoApp.OutputDataReceived += new DataReceivedEventHandler(echoApp_OutputDataReceived);
    echoApp.StartInfo = psi;
    echoApp.Start();
    echoApp.BeginOutputReadLine();
    echoApp.BeginErrorReadLine();
    echoApp.StandardInput.AutoFlush = true;

    string str = "";
    while (str != "end")
    {
        str = Console.ReadLine();
        echoApp.StandardInput.WriteLine(str);
    }
    echoApp.CancelOutputRead();
    echoApp.CancelErrorRead();
    echoApp.Close();
}

static void echoApp_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
    Console.WriteLine("stdout: {0}", e.Data);
}

static void echoApp_ErrorDataReceived(object sender, DataReceivedEventArgs e)
{
    Console.WriteLine("stderr: {0}", e.Data);
}

and the little echoApp…

//echoApp
static void Main(string[] args)
{
    string str="";
    while (str != "end")
    {
        str = Console.ReadLine();
        Console.WriteLine(str);
    }
}