Java tutorial
/* * Copyright 2006-2014 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.batch.core.launch.support; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.batch.core.BatchStatus; import org.springframework.batch.core.ExitStatus; import org.springframework.batch.core.Job; import org.springframework.batch.core.JobExecution; import org.springframework.batch.core.JobInstance; import org.springframework.batch.core.JobParameters; import org.springframework.batch.core.JobParametersInvalidException; import org.springframework.batch.core.StepExecution; import org.springframework.batch.core.launch.JobLauncher; import org.springframework.batch.core.repository.JobExecutionAlreadyRunningException; import org.springframework.batch.core.repository.JobInstanceAlreadyCompleteException; import org.springframework.batch.core.repository.JobRepository; import org.springframework.batch.core.repository.JobRestartException; import org.springframework.beans.factory.InitializingBean; import org.springframework.core.task.SyncTaskExecutor; import org.springframework.core.task.TaskExecutor; import org.springframework.core.task.TaskRejectedException; import org.springframework.util.Assert; /** * Simple implementation of the {@link JobLauncher} interface. The Spring Core * {@link TaskExecutor} interface is used to launch a {@link Job}. This means * that the type of executor set is very important. If a * {@link SyncTaskExecutor} is used, then the job will be processed * <strong>within the same thread that called the launcher.</strong> Care should * be taken to ensure any users of this class understand fully whether or not * the implementation of TaskExecutor used will start tasks synchronously or * asynchronously. The default setting uses a synchronous task executor. * * There is only one required dependency of this Launcher, a * {@link JobRepository}. The JobRepository is used to obtain a valid * JobExecution. The Repository must be used because the provided {@link Job} * could be a restart of an existing {@link JobInstance}, and only the * Repository can reliably recreate it. * * @author Lucas Ward * @author Dave Syer * @author Will Schipp * @author Michael Minella * * @since 1.0 * * @see JobRepository * @see TaskExecutor */ public class SimpleJobLauncher implements JobLauncher, InitializingBean { protected static final Log logger = LogFactory.getLog(SimpleJobLauncher.class); private JobRepository jobRepository; private TaskExecutor taskExecutor; /** * Run the provided job with the given {@link JobParameters}. The * {@link JobParameters} will be used to determine if this is an execution * of an existing job instance, or if a new one should be created. * * @param job the job to be run. * @param jobParameters the {@link JobParameters} for this particular * execution. * @return JobExecutionAlreadyRunningException if the JobInstance already * exists and has an execution already running. * @throws JobRestartException if the execution would be a re-start, but a * re-start is either not allowed or not needed. * @throws JobInstanceAlreadyCompleteException if this instance has already * completed successfully * @throws JobParametersInvalidException */ @Override public JobExecution run(final Job job, final JobParameters jobParameters) throws JobExecutionAlreadyRunningException, JobRestartException, JobInstanceAlreadyCompleteException, JobParametersInvalidException { Assert.notNull(job, "The Job must not be null."); Assert.notNull(jobParameters, "The JobParameters must not be null."); final JobExecution jobExecution; JobExecution lastExecution = jobRepository.getLastJobExecution(job.getName(), jobParameters); if (lastExecution != null) { if (!job.isRestartable()) { throw new JobRestartException("JobInstance already exists and is not restartable"); } /* * validate here if it has stepExecutions that are UNKNOWN, STARTING, STARTED and STOPPING * retrieve the previous execution and check */ for (StepExecution execution : lastExecution.getStepExecutions()) { BatchStatus status = execution.getStatus(); if (status.isRunning() || status == BatchStatus.STOPPING) { throw new JobExecutionAlreadyRunningException( "A job execution for this job is already running: " + lastExecution); } else if (status == BatchStatus.UNKNOWN) { throw new JobRestartException("Cannot restart step [" + execution.getStepName() + "] from UNKNOWN status. " + "The last execution ended with a failure that could not be rolled back, " + "so it may be dangerous to proceed. Manual intervention is probably necessary."); } } } // Check the validity of the parameters before doing creating anything // in the repository... job.getJobParametersValidator().validate(jobParameters); /* * There is a very small probability that a non-restartable job can be * restarted, but only if another process or thread manages to launch * <i>and</i> fail a job execution for this instance between the last * assertion and the next method returning successfully. */ jobExecution = jobRepository.createJobExecution(job.getName(), jobParameters); try { taskExecutor.execute(new Runnable() { @Override public void run() { try { logger.info("Job: [" + job + "] launched with the following parameters: [" + jobParameters + "]"); job.execute(jobExecution); logger.info("Job: [" + job + "] completed with the following parameters: [" + jobParameters + "] and the following status: [" + jobExecution.getStatus() + "]"); } catch (Throwable t) { logger.info("Job: [" + job + "] failed unexpectedly and fatally with the following parameters: [" + jobParameters + "]", t); rethrow(t); } } private void rethrow(Throwable t) { if (t instanceof RuntimeException) { throw (RuntimeException) t; } else if (t instanceof Error) { throw (Error) t; } throw new IllegalStateException(t); } }); } catch (TaskRejectedException e) { jobExecution.upgradeStatus(BatchStatus.FAILED); if (jobExecution.getExitStatus().equals(ExitStatus.UNKNOWN)) { jobExecution.setExitStatus(ExitStatus.FAILED.addExitDescription(e)); } jobRepository.update(jobExecution); } return jobExecution; } /** * Set the JobRepsitory. * * @param jobRepository */ public void setJobRepository(JobRepository jobRepository) { this.jobRepository = jobRepository; } /** * Set the TaskExecutor. (Optional) * * @param taskExecutor */ public void setTaskExecutor(TaskExecutor taskExecutor) { this.taskExecutor = taskExecutor; } /** * Ensure the required dependencies of a {@link JobRepository} have been * set. */ @Override public void afterPropertiesSet() throws Exception { Assert.state(jobRepository != null, "A JobRepository has not been set."); if (taskExecutor == null) { logger.info("No TaskExecutor has been set, defaulting to synchronous executor."); taskExecutor = new SyncTaskExecutor(); } } }