Add utility method to get identifying job parameters

Author: fmbenhassine

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

@@ -329,6 +329,21 @@ public Map<String, JobParameter<?>> getParameters() {
 		return Collections.unmodifiableMap(parameters);
 	}
 
+	/**
+	 * Get a map of identifying parameters.
+	 * @since 5.1
+	 * @return an unmodifiable map containing identifying parameters.
+	 */
+	public Map<String, JobParameter<?>> getIdentifyingParameters() {
+		Map<String, JobParameter<?>> identifyingParameters = new HashMap<>();
+		for (Map.Entry<String, JobParameter<?>> entry : this.parameters.entrySet()) {
+			if (entry.getValue().isIdentifying()) {
+				identifyingParameters.put(entry.getKey(), entry.getValue());
+			}
+		}
+		return Collections.unmodifiableMap(identifyingParameters);
+	}
+
 	/**
 	 * @return {@code true} if the parameters object is empty or {@code false} otherwise.
 	 */

spring-batch-core/src/main/java/org/springframework/batch/core/repository/dao/Jackson2ExecutionContextStringSerializer.java

@@ -176,6 +176,9 @@ private abstract class JobParametersMixIn {
 			@JsonIgnore
 			abstract boolean isEmpty();
 
+			@JsonIgnore
+			abstract Map<String, JobParameter<?>> getIdentifyingParameters();
+
 		}
 
 		private class JobParameterSerializer extends StdSerializer<JobParameter> {

spring-batch-core/src/test/java/org/springframework/batch/core/JobParametersTests.java

@@ -187,6 +187,25 @@ void testSerialization() {
 		assertEquals(params, SerializationUtils.clone(params));
 	}
 
+	@Test
+	void testGetIdentifyingParameters() {
+		// given
+		Map<String, JobParameter<?>> parametersMap = new HashMap<>();
+		JobParameter<String> jobParameter1 = new JobParameter<>("value1", String.class, true);
+		JobParameter<String> jobParameter2 = new JobParameter<>("value2", String.class, false);
+		parametersMap.put("key1", jobParameter1);
+		parametersMap.put("key2", jobParameter2);
+		JobParameters parameters = new JobParameters(parametersMap);
+
+		// when
+		Map<String, JobParameter<?>> identifyingParameters = parameters.getIdentifyingParameters();
+
+		// then
+		assertEquals(1, identifyingParameters.size());
+		JobParameter<?> key1 = identifyingParameters.get("key1");
+		assertEquals(jobParameter1, key1);
+	}
+
 	@Test
 	void testLongReturnsNullWhenKeyDoesntExit() {
 		assertNull(new JobParameters().getLong("keythatdoesntexist"));