Class CommandInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

ecmwf.common.technical.CommandInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public final class CommandInputStream
extends FilterInputStream
implements AutoCloseable

A stream that connects an InputStream to the input of an external process, and allows reading the output produced by the process. This class manages the lifecycle of the associated process and its input/output streams, and handles stderr asynchronously to avoid potential deadlocks.

Field Summary

Fields inherited from class FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
CommandInputStream(InputStream in, Process process)	Creates a CommandInputStream that connects the given InputStream to the standard input of a process, and allows reading the standard output of that process.
CommandInputStream(InputStream in, String[] command)	Creates a CommandInputStream by executing the given command.

Method Summary

Modifier and Type	Method	Description
int	available()	Returns the number of bytes that can be read without blocking.
void	close()	Closes this stream and performs all associated cleanup.
int	read()	Reads a byte of data from the process's output.
int	read(byte[] b)	Reads bytes into a buffer from the process's output.
int	read(byte[] b, int off, int len)	Reads up to len bytes of data from the process's output.
long	skip(long n)	Skips over and discards n bytes of data from the process's output.

Methods inherited from class FilterInputStream

mark, markSupported, reset

Methods inherited from class InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Methods inherited from class Object

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

Constructor Details

CommandInputStream

public CommandInputStream(InputStream in,
 Process process)
                   throws IOException

Creates a CommandInputStream that connects the given InputStream to the standard input of a process, and allows reading the standard output of that process.

Parameters:

in - The InputStream from which to send data to the process's input.

process - The process to execute and communicate with.

Throws:

IOException - If any I/O error occurs during setup.

CommandInputStream

public CommandInputStream(InputStream in,
 String[] command)
                   throws IOException

Creates a CommandInputStream by executing the given command.

Parameters:

in - The InputStream to send to the process's stdin.

command - The command to run.

Throws:

IOException - If an error occurs while launching the process.

Method Details

close

public void close()
           throws IOException

Closes this stream and performs all associated cleanup.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class FilterInputStream

Throws:

IOException - If an error occurs during closing.

read

public int read()
         throws IOException

Reads a byte of data from the process's output.

Overrides:

read in class FilterInputStream

Throws:

IOException

read

public int read(byte[] b)
         throws IOException

Reads bytes into a buffer from the process's output.

Overrides:

read in class FilterInputStream

Throws:

IOException

read

public int read(byte[] b,
 int off,
 int len)
         throws IOException

Reads up to len bytes of data from the process's output.

Overrides:

read in class FilterInputStream

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Skips over and discards n bytes of data from the process's output.

Overrides:

skip in class FilterInputStream

Throws:

IOException

available

public int available()
              throws IOException

Returns the number of bytes that can be read without blocking.

Overrides:

available in class FilterInputStream

Throws:

IOException