org.springframework.batch.core.step.tasklet

Class SystemCommandTasklet

java.lang.Object

org.springframework.batch.core.listener.StepExecutionListenerSupport

org.springframework.batch.core.step.tasklet.SystemCommandTasklet

All Implemented Interfaces:

StoppableTasklet, Tasklet, StepExecutionListener, StepListener, org.springframework.beans.factory.InitializingBean

public class SystemCommandTasklet
extends StepExecutionListenerSupport
implements StoppableTasklet, org.springframework.beans.factory.InitializingBean

Tasklet that executes a system command. The system command is executed asynchronously using injected setTaskExecutor(TaskExecutor) - timeout value is required to be set, so that the batch job does not hang forever if the external process hangs. Tasklet periodically checks for termination status (i.e. setCommand(String) finished its execution or setTimeout(long) expired or job was interrupted). The check interval is given by setTerminationCheckInterval(long). When job interrupt is detected tasklet's execution is terminated immediately by throwing JobInterruptedException. setInterruptOnCancel(boolean) specifies whether the tasklet should attempt to interrupt the thread that executes the system command if it is still running when tasklet exits (abnormally).

Author:

Robert Kasanicky, Will Schipp

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.apache.commons.logging.Log	logger

Constructor Summary

Constructors

Constructor and Description
SystemCommandTasklet()

Method Summary

Modifier and Type	Method and Description
void	afterPropertiesSet()
void	beforeStep(StepExecution stepExecution) Get a reference to StepExecution for interrupt checks during system command execution.
RepeatStatus	execute(StepContribution contribution, ChunkContext chunkContext) Execute system command and map its exit code to ExitStatus using SystemProcessExitCodeMapper.
void	setCommand(java.lang.String command)
void	setEnvironmentParams(java.lang.String[] envp)
void	setInterruptOnCancel(boolean interruptOnCancel) If true tasklet will attempt to interrupt the thread executing the system command if setTimeout(long) has been exceeded or user interrupts the job.
void	setJobExplorer(JobExplorer jobExplorer)
void	setSystemProcessExitCodeMapper(SystemProcessExitCodeMapper systemProcessExitCodeMapper)
void	setTaskExecutor(org.springframework.core.task.TaskExecutor taskExecutor) Sets the task executor that will be used to execute the system command NB! Avoid using a synchronous task executor
void	setTerminationCheckInterval(long checkInterval) The time interval how often the tasklet will check for termination status.
void	setTimeout(long timeout) Timeout in milliseconds.
void	setWorkingDirectory(java.lang.String dir)
void	stop() Will interrupt the thread executing the system command only if setInterruptOnCancel(boolean) has been set to true.

Methods inherited from class org.springframework.batch.core.listener.StepExecutionListenerSupport

afterStep

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static final org.apache.commons.logging.Log logger

Constructor Detail

SystemCommandTasklet

public SystemCommandTasklet()

Method Detail

execute

@Nullable
public RepeatStatus execute(StepContribution contribution,
                                      ChunkContext chunkContext)
                               throws java.lang.Exception

Execute system command and map its exit code to ExitStatus using SystemProcessExitCodeMapper.

Specified by:

execute in interface Tasklet

Parameters:

contribution - mutable state to be passed back to update the current step execution

chunkContext - attributes shared between invocations but not between restarts

Returns:

an RepeatStatus indicating whether processing is continuable. Returning null is interpreted as RepeatStatus.FINISHED

Throws:

java.lang.Exception - thrown if error occurs during execution.

setCommand

public void setCommand(java.lang.String command)

Parameters:

command - command to be executed in a separate system process

setEnvironmentParams

public void setEnvironmentParams(java.lang.String[] envp)

Parameters:

envp - environment parameter values, inherited from parent process when not set (or set to null).

setWorkingDirectory

public void setWorkingDirectory(java.lang.String dir)

Parameters:

dir - working directory of the spawned process, inherited from parent process when not set (or set to null).

afterPropertiesSet

public void afterPropertiesSet()
                        throws java.lang.Exception

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Throws:

java.lang.Exception

setJobExplorer

public void setJobExplorer(JobExplorer jobExplorer)

setSystemProcessExitCodeMapper

public void setSystemProcessExitCodeMapper(SystemProcessExitCodeMapper systemProcessExitCodeMapper)

Parameters:

systemProcessExitCodeMapper - maps system process return value to ExitStatus returned by Tasklet. SimpleSystemProcessExitCodeMapper is used by default.

setTimeout

public void setTimeout(long timeout)

Timeout in milliseconds.

Parameters:

timeout - upper limit for how long the execution of the external program is allowed to last.

setTerminationCheckInterval

public void setTerminationCheckInterval(long checkInterval)

The time interval how often the tasklet will check for termination status.

Parameters:

checkInterval - time interval in milliseconds (1 second by default).

beforeStep

public void beforeStep(StepExecution stepExecution)

Get a reference to StepExecution for interrupt checks during system command execution.

Specified by:

beforeStep in interface StepExecutionListener

Overrides:

beforeStep in class StepExecutionListenerSupport

Parameters:

stepExecution - instance of StepExecution.

setTaskExecutor

public void setTaskExecutor(org.springframework.core.task.TaskExecutor taskExecutor)

Sets the task executor that will be used to execute the system command NB! Avoid using a synchronous task executor

Parameters:

taskExecutor - instance of TaskExecutor.

setInterruptOnCancel

public void setInterruptOnCancel(boolean interruptOnCancel)

If true tasklet will attempt to interrupt the thread executing the system command if setTimeout(long) has been exceeded or user interrupts the job. false by default

Parameters:

interruptOnCancel - boolean determines if process should be interrupted

stop

public void stop()

Will interrupt the thread executing the system command only if setInterruptOnCancel(boolean) has been set to true. Otherwise the underlying command will be allowed to finish before the tasklet ends.

Specified by:

stop in interface StoppableTasklet

Since:

3.0

See Also:

StoppableTasklet.stop()