org.springframework.webflow.engine.ViewState Maven / Gradle / Ivy
/*
* Copyright 2004-2007 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.engine;
import org.springframework.core.style.ToStringCreator;
import org.springframework.util.Assert;
import org.springframework.webflow.execution.FlowExecutionException;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.ViewSelection;
/**
* A view state is a state that issues a response to the user, for example, for soliciting form input.
*
* To accomplish this, a ViewState makes a {@link ViewSelection}, which contains the necessary
* information to issue a suitable response.
*
* @see org.springframework.webflow.engine.ViewSelector
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class ViewState extends TransitionableState {
/**
* The list of actions to be executed when this state is entered.
*/
private ActionList renderActionList = new ActionList();
/**
* The factory for the view selection to return when this state is entered.
*/
private ViewSelector viewSelector = NullViewSelector.INSTANCE;
/**
* Create a new view state.
* @param flow the owning flow
* @param id the state identifier (must be unique to the flow)
* @throws IllegalArgumentException when this state cannot be added to given flow, e.g. because the id is not unique
*/
public ViewState(Flow flow, String id) throws IllegalArgumentException {
super(flow, id);
}
/**
* Returns the strategy used to select the view to render in this view state.
*/
public ViewSelector getViewSelector() {
return viewSelector;
}
/**
* Sets the strategy used to select the view to render in this view state.
*/
public void setViewSelector(ViewSelector viewSelector) {
Assert.notNull(viewSelector, "The view selector to make view selections is required");
this.viewSelector = viewSelector;
}
/**
* Returns the list of actions executable by this view state on entry and on refresh. The returned list is mutable.
* @return the state action list
*/
public ActionList getRenderActionList() {
return renderActionList;
}
/**
* Specialization of State's doEnter template method that executes behavior specific to this state
* type in polymorphic fashion.
*
* Returns a view selection indicating a response to issue. The view selection typically contains all the data
* necessary to issue the response.
* @param context the control context for the currently executing flow, used by this state to manipulate the flow
* execution
* @return a view selection serving as a response instruction
* @throws FlowExecutionException if an exception occurs in this state
*/
protected ViewSelection doEnter(RequestControlContext context) throws FlowExecutionException {
if (viewSelector.isEntrySelectionRenderable(context)) {
// the entry selection will be rendered!
renderActionList.execute(context);
}
return viewSelector.makeEntrySelection(context);
}
/**
* Request that the current view selection be reconstituted to support reissuing the response. This is an idempotent
* operation that may be safely called any number of times on a paused execution, used primarily to support a flow
* execution redirect.
* @param context the request context
* @return the view selection
* @throws FlowExecutionException if an exception occurs in this state
*/
public ViewSelection refresh(RequestContext context) throws FlowExecutionException {
renderActionList.execute(context);
return viewSelector.makeRefreshSelection(context);
}
protected void appendToString(ToStringCreator creator) {
creator.append("viewSelector", viewSelector);
super.appendToString(creator);
}
}