BATCH-1589: add existing params when incrementing run.id

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

@@ -84,7 +84,8 @@ public class JobParameters implements Serializable {
 	 * @return The <code>String</code> value
 	 */
 	public String getString(String key){
-		return parameters.get(key).toString();
+		JobParameter value = parameters.get(key);
+		return value==null ? null : value.toString();
 	}
 	
 	/**

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

@@ -25,16 +25,27 @@ import org.springframework.batch.core.JobParametersIncrementer;
 public class RunIdIncrementer implements JobParametersIncrementer {
 
 	private static String RUN_ID_KEY = "run.id";
+	
+	private String key = RUN_ID_KEY;
+	
+	/**
+	 * The name of the run id in the job parameters.  Defaults to "run.id".
+	 * 
+	 * @param key the key to set
+	 */
+	public void setKey(String key) {
+		this.key = key;
+	}
 
 	/**
-	 * Increment the run.id parameter.
+	 * Increment the run.id parameter (starting with 1).
 	 */
 	public JobParameters getNext(JobParameters parameters) {
-		if (parameters == null || parameters.isEmpty()) {
-			return new JobParametersBuilder().addLong(RUN_ID_KEY, 1L).toJobParameters();
+		if (parameters == null) {
+			parameters = new JobParameters();
 		}
-		long id = parameters.getLong(RUN_ID_KEY, 1L) + 1;
-		return new JobParametersBuilder().addLong(RUN_ID_KEY, id).toJobParameters();
+		long id = parameters.getLong(key, 0L) + 1;
+		return new JobParametersBuilder(parameters).addLong(key, id).toJobParameters();
 	}
 
 }

spring-batch-core/src/test/java/org/springframework/batch/core/launch/support/RunIdIncrementerTests.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2006-2010 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 static org.junit.Assert.*;
+
+import org.junit.Test;
+import org.springframework.batch.core.JobParameters;
+import org.springframework.batch.core.JobParametersBuilder;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class RunIdIncrementerTests {
+	
+	private RunIdIncrementer incrementer = new RunIdIncrementer();
+
+	@Test
+	public void testGetNext() {
+		JobParameters next = incrementer.getNext(null);
+		assertEquals(1, next.getLong("run.id"));
+		assertEquals(2, incrementer.getNext(next).getLong("run.id"));
+	}
+
+	@Test
+	public void testGetNextAppends() {
+		JobParameters next = incrementer.getNext(new JobParametersBuilder().addString("foo", "bar").toJobParameters());
+		assertEquals(1, next.getLong("run.id"));
+		assertEquals("bar", next.getString("foo"));
+	}
+
+	@Test
+	public void testGetNextNamed() {
+		incrementer.setKey("foo");
+		JobParameters next = incrementer.getNext(null);
+		assertEquals(1, next.getLong("foo"));
+	}
+
+}