monq.stuff

Class Exec

java.lang.Object

monq.stuff.Exec

All Implemented Interfaces:

java.lang.Runnable, Service

public class Exec
extends java.lang.Object
implements Service

encapsulates a java.lang.Process object, feeds it with input and collects the output.

Example use:

    Process p = new Process("your command here");
    Exec exec = new Exec(p);
    if( !exec.done() ) {
       // do something with exec.getErrorText()
       // check p.exitValue() if the above is empty
    }

Version:

$Revision: 1.5 $, $Date: 2005-11-17 09:34:47 $

Author:

© 2004 Harald Kirsch

Constructor Summary

Constructors

Constructor and Description
Exec(java.lang.Process p) creates an execution environment for the running process p which immediately closes its standard input and collects standard output and standard error output internally.
Exec(java.lang.Process p, java.io.InputStream in, java.io.OutputStream output, java.io.OutputStream error) creates an execution environment which feeds the given process input, collects its output and registers the exit code.

Method Summary

Modifier and Type	Method and Description
boolean	done() starts feeding the process by calling run(), waits for it to finish and then returns ok().
boolean	finished() asynchronuously tests if the process finished in the meantime.
java.lang.String	getErrorText() if no explicit output sink was specified in the constructor, this method returns the output collected from the process.
java.lang.Exception	getException() returns whatever Exception happened in one of the Pipe threads used to copy data to the process or read output or error from the process.
java.lang.String	getOutputText() if no explicit error output sink was specified in the constructor, this method returns the error text collected from the process.
boolean	ok() returns true if the process execution went well.
void	run() feeds the process with input and collects the output according to the information given in the constructor.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Exec

public Exec(java.lang.Process p,
            java.io.InputStream in,
            java.io.OutputStream output,
            java.io.OutputStream error)

creates an execution environment which feeds the given process input, collects its output and registers the exit code. You have to call either run() or done() explicitly to get things going.

Parameters:

p - a running process

in - is the data source to feed into the standard input of p. May be null in which case the standard input of p is immediately closed.

output - is the output sink for the standard output of p. It may be null in which case the output is collected internally and made available via getOutputText().

error - is the sink for the standard error output of p. If it is null, it is collected and made available via getErrorText().

Exec

public Exec(java.lang.Process p)

creates an execution environment for the running process p which immediately closes its standard input and collects standard output and standard error output internally. The latter two can then be retrieved with getOutputText() and it is null, it is collected and made available via getErrorText().

This is equivalent to Exec(p, null, null, null).

Method Detail

finished

public boolean finished()

asynchronuously tests if the process finished in the meantime.

ok

public boolean ok()

returns true if the process execution went well. The return value will be false if either

• the exit value was non-zero,
• an exception was thrown by one of the threads piping to from and to the subprocess (see getException()),
• no output sink was set up in the constructor for the error output stream of the process and some output was generated.

Note:If an error output sink was explicitely given in the constructor, it is not watched to see if any data is produced. In this case ok() merely checks the exit value of the process and exceptions.

Throws:

java.lang.IllegalStateException - if the process has not finished yet.

done

public boolean done()

starts feeding the process by calling run(), waits for it to finish and then returns ok().

getException

public java.lang.Exception getException()

returns whatever Exception happened in one of the Pipe threads used to copy data to the process or read output or error from the process. Since there are up to three data streams connected to the process in parallel threads, it can not be guaranteed that the first one failing will be reported. Rather they are prioritized in the order stdin, stdout, stderr.

Specified by:

getException in interface Service

getErrorText

public java.lang.String getErrorText()

if no explicit output sink was specified in the constructor, this method returns the output collected from the process.

Throws:

java.lang.IllegalStateException - if the process has not finished yet.

getOutputText

public java.lang.String getOutputText()

if no explicit error output sink was specified in the constructor, this method returns the error text collected from the process.

Throws:

java.lang.IllegalStateException - if the process has not finished yet.

run

public void run()

feeds the process with input and collects the output according to the information given in the constructor. The method will return when the process has finished and all data produced by it was read. In addition, run() will kill the process and return, if the thread it is running in is interrupted.

Specified by:

run in interface java.lang.Runnable