added simple snapshot factory

spring-webflow/src/main/java/org/springframework/webflow/execution/repository/snapshot/SimpleFlowExecutionSnapshotFactory.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2004-2008 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.webflow.execution.repository.snapshot;
+
+import org.springframework.util.Assert;
+import org.springframework.webflow.core.collection.MutableAttributeMap;
+import org.springframework.webflow.definition.FlowDefinition;
+import org.springframework.webflow.definition.registry.FlowDefinitionLocator;
+import org.springframework.webflow.execution.FlowExecution;
+import org.springframework.webflow.execution.FlowExecutionFactory;
+import org.springframework.webflow.execution.FlowExecutionKey;
+import org.springframework.webflow.execution.FlowExecutionKeyFactory;
+import org.springframework.webflow.execution.repository.FlowExecutionRestorationFailureException;
+
+/**
+ * A factory that creates new flow execution snapshot instances that simply wraps an underlying
+ * {@link FlowExecution flow execution} instance.
+ * 
+ * Note: this class is generally only suitable for use with a repository that has maxSnapshots set to 1, since no actual
+ * copies of the execution data are made by this factory. This class exists to support the use case where taking copies
+ * of flow execution state is not needed.
+ * 
+ * @author Keith Donald
+ */
+public class SimpleFlowExecutionSnapshotFactory implements FlowExecutionSnapshotFactory {
+
+	private FlowExecutionFactory flowExecutionFactory;
+
+	private FlowDefinitionLocator flowDefinitionLocator;
+
+	/**
+	 * Creates a new simple flow execution snapshot factory
+	 * @param flowDefinitionLocator the flow definition locator
+	 * @param flowExecutionFactory the flow execution factory
+	 */
+	public SimpleFlowExecutionSnapshotFactory(FlowExecutionFactory flowExecutionFactory,
+			FlowDefinitionLocator flowDefinitionLocator) {
+		Assert.notNull(flowExecutionFactory, "The FlowExecutionFactory to restore transient flow state is required");
+		Assert.notNull(flowDefinitionLocator, "The FlowDefinitionLocator to restore FlowDefinitions is required");
+		this.flowExecutionFactory = flowExecutionFactory;
+		this.flowDefinitionLocator = flowDefinitionLocator;
+	}
+
+	public FlowExecutionSnapshot createSnapshot(FlowExecution flowExecution) throws SnapshotCreationException {
+		return new SimpleFlowExecutionSnapshot(flowExecution);
+	}
+
+	public FlowExecution restoreExecution(FlowExecutionSnapshot snapshot, String flowId, FlowExecutionKey key,
+			MutableAttributeMap conversationScope, FlowExecutionKeyFactory keyFactory)
+			throws FlowExecutionRestorationFailureException {
+		SimpleFlowExecutionSnapshot snapshotImpl = (SimpleFlowExecutionSnapshot) snapshot;
+		FlowDefinition def = flowDefinitionLocator.getFlowDefinition(flowId);
+		FlowExecution execution = snapshotImpl.getFlowExecution();
+		flowExecutionFactory.restoreFlowExecution(execution, def, key, conversationScope, flowDefinitionLocator);
+		return execution;
+	}
+
+	private static class SimpleFlowExecutionSnapshot extends FlowExecutionSnapshot {
+		private FlowExecution flowExecution;
+
+		public SimpleFlowExecutionSnapshot(FlowExecution flowExecution) {
+			this.flowExecution = flowExecution;
+		}
+
+		public FlowExecution getFlowExecution() {
+			return flowExecution;
+		}
+	}
+
+}