handler mapping

spring-webflow/src/main/java/org/springframework/webflow/mvc/servlet/FlowIdHandlerMapping.java

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+/*
+ * 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.mvc.servlet;
+
+import javax.servlet.ServletContext;
+import javax.servlet.http.HttpServletRequest;
+
+import org.springframework.web.servlet.handler.AbstractHandlerMapping;
+import org.springframework.webflow.context.servlet.DefaultFlowUrlHandler;
+import org.springframework.webflow.context.servlet.FlowUrlHandler;
+import org.springframework.webflow.definition.FlowDefinition;
+import org.springframework.webflow.definition.registry.FlowDefinitionRegistry;
+
+/**
+ * Implementation of {@link org.springframework.web.servlet.HandlerMapping} that follows a simple convention for
+ * creating URL path mappings from the <i>ids</i> of registered {@link FlowDefinition flow definitions}.
+ * 
+ * This implementation returns a FlowHandler that invokes a flow if the current request path matches the id of a flow in
+ * the configured {@link FlowDefinitionRegistry}. Alternatively, a custom {@link FlowHandler} may also be registered
+ * with in containing ApplicationContext with that id and it will be returned. This allows for more control over the
+ * invocation of a flow from Spring MVC environment.
+ * 
+ * Null is returned in the case of no flow id match, allowing the next handler mapping in the chain to execute.
+ * 
+ * @author Keith Donald
+ */
+public class FlowIdHandlerMapping extends AbstractHandlerMapping {
+
+	private FlowUrlHandler flowUrlHandler = new DefaultFlowUrlHandler();
+
+	private FlowDefinitionRegistry flowRegistry;
+
+	/**
+	 * Returns the registry of flows to query when this mapping is tested.
+	 * @return the flow definition registry
+	 */
+	public FlowDefinitionRegistry getFlowRegistry() {
+		return flowRegistry;
+	}
+
+	/**
+	 * Sets the registry of flows to query when this mapping is tested. Optional. If not set, this handler mapping will
+	 * look in the containing application context for a bean with id <code>flowRegistry</code>.
+	 * @param flowRegistry the flow definition registry
+	 */
+	public void setFlowRegistry(FlowDefinitionRegistry flowRegistry) {
+		this.flowRegistry = flowRegistry;
+	}
+
+	/**
+	 * Returns the configured flow url handler.
+	 */
+	public FlowUrlHandler getFlowUrlHandler() {
+		return flowUrlHandler;
+	}
+
+	/**
+	 * Sets the flow URL handler, which allows customization for how the flow id is determined for each request tested
+	 * by this mapping. Defaults to a {@link DefaultFlowUrlHandler}.
+	 * @param flowUrlHandler the flow URL handler
+	 */
+	public void setFlowUrlHandler(FlowUrlHandler flowUrlHandler) {
+		this.flowUrlHandler = flowUrlHandler;
+	}
+
+	protected void initServletContext(ServletContext servletContext) {
+		if (flowRegistry == null) {
+			flowRegistry = (FlowDefinitionRegistry) getApplicationContext().getBean("flowRegistry",
+					FlowDefinitionRegistry.class);
+		}
+	}
+
+	protected Object getHandlerInternal(HttpServletRequest request) throws Exception {
+		String flowId = flowUrlHandler.getFlowId(request);
+		if (getApplicationContext().containsBean(flowId)) {
+			Object handler = getApplicationContext().getBean(flowId);
+			if (handler instanceof FlowHandler) {
+				return handler;
+			}
+		}
+		if (flowRegistry.containsFlowDefinition(flowId)) {
+			return new DefaultFlowHandler(flowId);
+		}
+		return null;
+	}
+
+	private static class DefaultFlowHandler extends AbstractFlowHandler {
+		private String flowId;
+
+		public DefaultFlowHandler(String flowId) {
+			this.flowId = flowId;
+		}
+
+		public String getFlowId() {
+			return flowId;
+		}
+	}
+
+}