org.springframework.webflow.action.MultiAction Maven / Gradle / Ivy
/*
* 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.action;
import org.springframework.util.Assert;
import org.springframework.webflow.execution.Event;
import org.springframework.webflow.execution.RequestContext;
/**
* Action implementation that bundles two or more action execution methods into a single class. Action execution methods
* defined by subclasses must adhere to the following signature:
*
*
* public Event ${method}(RequestContext context) throws Exception;
*
*
* When this action is invoked, by default the id of the calling action state state is treated as the
* action execution method name. Alternatively, the execution method name may be explicitly specified as a attribute of
* the calling action state.
*
* For example, the following action state definition:
*
*
* <action-state id="search">
* <evaluate expression="searchAction.executeSearch"/>
* <transition on="success" to="results"/>
* </action-state>
*
*
* ... when entered, executes the method:
*
*
* public Event search(RequestContext context) throws Exception;
*
*
*
* One use of the MultiAction is to centralize all command logic for a flow in one place. Another use is to centralize
* form setup and submit logic in one place, or CRUD (create/read/update/delete) operations for a single domain object
* in one place.
*
* @see MultiAction.MethodResolver
* @see org.springframework.webflow.action.DefaultMultiActionMethodResolver
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class MultiAction extends AbstractAction {
/**
* A cache for dispatched action execute methods. The default signature is
* public Event ${method}(RequestContext context) throws Exception;.
*/
private DispatchMethodInvoker methodInvoker;
/**
* The action method resolver strategy.
*/
private MethodResolver methodResolver = new DefaultMultiActionMethodResolver();
/**
* Protected default constructor; not invokable for direct MultiAction instantiation. Intended for use by
* subclasses.
*
* Sets the target to this multi action instance.
* @see #setTarget(Object)
*/
protected MultiAction() {
setTarget(this);
}
/**
* Constructs a multi action that invokes methods on the specified target object. Note: invokable methods on the
* target must conform to the multi action method signature:
*
*
* public Event ${method}(RequestContext context) throws Exception;
*
*
* @param target the target of this multi action's invocations
*/
public MultiAction(Object target) {
setTarget(target);
}
/**
* Sets the target of this multi action's invocations.
* @param target the target
*/
protected final void setTarget(Object target) {
methodInvoker = new DispatchMethodInvoker(target, RequestContext.class);
}
/**
* Get the strategy used to resolve action execution method names.
*/
public MethodResolver getMethodResolver() {
return methodResolver;
}
/**
* Set the strategy used to resolve action execution method names. Allows full control over the method resolution
* algorithm. Defaults to {@link DefaultMultiActionMethodResolver}.
*/
public void setMethodResolver(MethodResolver methodResolver) {
this.methodResolver = methodResolver;
}
protected final Event doExecute(RequestContext context) throws Exception {
String method = getMethodResolver().resolveMethod(context);
Object obj = methodInvoker.invoke(method, context);
if (obj != null) {
Assert.isInstanceOf(Event.class, obj, "The '" + method + "' action execution method on target object '"
+ methodInvoker.getTarget() + "' did not return an Event object but '" + obj + "' of type "
+ obj.getClass().getName() + " -- "
+ "Programmer error; make sure the method signature conforms to "
+ "'public Event ${method}(RequestContext context) throws Exception;'.");
}
return (Event) obj;
}
/**
* Strategy interface used by the MultiAction to map a request context to the name of an action execution method.
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public interface MethodResolver {
/**
* Resolve a method name from given flow execution request context.
* @param context the flow execution request context
* @return the name of the method that should handle action execution
*/
String resolveMethod(RequestContext context);
}
}