how to redirect stdin to java Runtime.exec?

Question

I want to execute some sql scripts using Java\'s Runtime.exec method. I intend to invoke mysql.exe / mysql.sh and redirect the script file to this process. From the command

Answer 1

Redirection is a functionality of the OS shell/cmd enviroments. To invoke them correctly we should use Runtime.exec(String[]) instead of Runtime.exec(String). Here is the code.

public Result executeCmd(String[] cmds, boolean waitForResult)
{
    Result result = new Result();
    result.output = "";
    try
    {
        for(int i=0;i 1)
            process=Runtime.getRuntime().exec(cmds);
        else
            process=Runtime.getRuntime().exec(cmds[0]);
        if (waitForResult)
        {
            StreamGobbler errordataReader = new StreamGobbler(process
                    .getErrorStream(), "ERROR");

            StreamGobbler outputdataReader = new StreamGobbler(process
                    .getInputStream(), "OUTPUT");

            errordataReader.start();
            outputdataReader.start();

            int exitVal = process.waitFor();
            errordataReader.join();
            outputdataReader.join();
            result.returnCode = exitVal;
            result.output = outputdataReader.output;
            result.error = errordataReader.output;
        }
    }
    catch (Exception exp)
    {
        result.exp = exp;
        result.returnCode = -1;
    }
    return result;
}

And call this method using

Result result = executeCmd(cmds, true);

where

CMD[0]::cmd
CMD[1]::/c
CMD[2]::.\mysql\bin\mysql --host= --port= -u   < .\scripts\create_tables.sql