Listener to copy parameters into execution context so that local step can be configured identically to remote step in a partition.

spring-batch-core/src/main/java/org/springframework/batch/core/listener/JobParameterExecutionContextCopyListener.java

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+/*
+ * Copyright 2006-2007 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.listener;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import org.springframework.batch.core.JobParameters;
+import org.springframework.batch.core.StepExecution;
+import org.springframework.batch.item.ExecutionContext;
+
+import com.sun.org.apache.xerces.internal.impl.xpath.XPath.Step;
+
+/**
+ * This class can be used to automatically copy items from the
+ * {@link JobParameters} to the {@link Step} {@link ExecutionContext}. A list of
+ * keys should be provided that correspond to the items in the {@link Step}
+ * {@link ExecutionContext} that should be copied.
+ * 
+ * @author Dave Syer
+ * @since 2.0
+ */
+public class JobParameterExecutionContextCopyListener extends StepExecutionListenerSupport {
+
+	private Collection<String> keys = null;
+
+	/**
+	 * @param keys A list of keys corresponding to items in the
+	 * {@link JobParameters} that should be copied.
+	 */
+	public void setKeys(String[] keys) {
+		this.keys = Arrays.asList(keys);
+	}
+
+	/**
+	 * Copy attributes from the {@link JobParameters} to the {@link Step}
+	 * {@link ExecutionContext}, if not already present. The the key is already
+	 * present we assume that a restart is in operation and the previous value
+	 * is needed. If the provided keys are empty defaults to copy all keys in
+	 * the {@link JobParameters}.
+	 */
+	@Override
+	public void beforeStep(StepExecution stepExecution) {
+		ExecutionContext stepContext = stepExecution.getExecutionContext();
+		JobParameters jobParameters = stepExecution.getJobParameters();
+		Collection<String> keys = this.keys;
+		if (keys == null) {
+			keys = jobParameters.getParameters().keySet();
+		}
+		for (String key : keys) {
+			if (!stepContext.containsKey(key)) {
+				stepContext.put(key, jobParameters.getParameters().get(key).getValue());
+			}
+		}
+	}
+}