RESOLVED - issue BATCH-1483: Make the JobParametersValidator instance accessible from the Job interface

spring-batch-core/src/main/java/org/springframework/batch/core/Job.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.batch.core;
 
+import org.springframework.batch.core.job.JobParametersValidator;
+
 /**
  * Batch domain object representing a job. Job is an explicit abstraction
  * representing the configuration of a job specified by a developer. It should
@@ -34,7 +36,7 @@ public interface Job {
 	 * @return true if this job can be restarted after a failure
 	 */
 	boolean isRestartable();
-	
+
 	/**
 	 * Run the {@link JobExecution} and update the meta information like status
 	 * and statistics as necessary. This method should not throw any exceptions
@@ -54,4 +56,14 @@ public interface Job {
 	 */
 	JobParametersIncrementer getJobParametersIncrementer();
 
+	/**
+	 * A validator for the job parameters of a {@link JobExecution}. Clients of
+	 * a Job may need to validate the parameters for a launch, before or during
+	 * the execution.
+	 * 
+	 * @return a validator that can be used to check parameter values (never
+	 * null)
+	 */
+	JobParametersValidator getJobParametersValidator();
+
 }

spring-batch-core/src/main/java/org/springframework/batch/core/configuration/support/GroupAwareJob.java

@@ -18,6 +18,7 @@ package org.springframework.batch.core.configuration.support;
 import org.springframework.batch.core.Job;
 import org.springframework.batch.core.JobExecution;
 import org.springframework.batch.core.JobParametersIncrementer;
+import org.springframework.batch.core.job.JobParametersValidator;
 
 /**
  * A {@link Job} that can optionally prepend a group name to another job's name,
@@ -87,6 +88,10 @@ public class GroupAwareJob implements Job {
 		return delegate.getJobParametersIncrementer();
 	}
 
+	public JobParametersValidator getJobParametersValidator() {
+		return delegate.getJobParametersValidator();
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * 

spring-batch-core/src/main/java/org/springframework/batch/core/job/AbstractJob.java

@@ -157,6 +157,10 @@ public abstract class AbstractJob implements Job, StepLocator, BeanNameAware, In
 	 * @return the step names
 	 */
 	public abstract Collection<String> getStepNames();
+	
+	public JobParametersValidator getJobParametersValidator() {
+		return jobParametersValidator;
+	}
 
 	/**
 	 * Boolean flag to prevent categorically a job from restarting, even if it

spring-batch-core/src/main/java/org/springframework/batch/core/job/DefaultJobParametersValidator.java

@@ -18,9 +18,32 @@ import org.springframework.util.Assert;
  */
 public class DefaultJobParametersValidator implements JobParametersValidator, InitializingBean {
 
-	private Collection<String> requiredKeys = new HashSet<String>();
+	private Collection<String> requiredKeys;
 
-	private Collection<String> optionalKeys = new HashSet<String>();
+	private Collection<String> optionalKeys;
+
+	/**
+	 * Convenient default constructor for unconstrained validation.
+	 */
+	public DefaultJobParametersValidator() {
+		this(new String[0], new String[0]);
+	}
+
+	/**
+	 * Create a new validator with the required and optional job parameter keys
+	 * provided.
+	 * 
+	 * @see DefaultJobParametersValidator#setOptionalKeys(String[])
+	 * @see DefaultJobParametersValidator#setRequiredKeys(String[])
+	 * 
+	 * @param requiredKeys the required keys
+	 * @param optionalKeys the optional keys
+	 */
+	public DefaultJobParametersValidator(String[] requiredKeys, String[] optionalKeys) {
+		super();
+		setRequiredKeys(requiredKeys);
+		setOptionalKeys(optionalKeys);
+	}
 
 	/**
 	 * Check that there are no overlaps between required and optional keys.

spring-batch-core/src/main/java/org/springframework/batch/core/launch/support/SimpleJobLauncher.java

@@ -52,7 +52,10 @@ import org.springframework.util.Assert;
  * Repository can reliably recreate it.
  * 
  * @author Lucas Ward
+ * @Author Dave Syer
+ * 
  * @since 1.0
+ * 
  * @see JobRepository
  * @see TaskExecutor
  */
@@ -93,21 +96,20 @@ public class SimpleJobLauncher implements JobLauncher, InitializingBean {
 			if (!job.isRestartable()) {
 				throw new JobRestartException("JobInstance already exists and is not restartable");
 			}
-			else {
-				/*
-				 * 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);
-			}
-		}
-		else {
-			jobExecution = jobRepository.createJobExecution(job.getName(), jobParameters);
 		}
 
+		// 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() {