org.springframework.webflow.ViewState Maven / Gradle / Ivy
/*
* Copyright 2002-2006 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;
import org.springframework.core.style.ToStringCreator;
import org.springframework.util.Assert;
/**
* A view state is a state in which a physical view resource should be rendered
* to the user, for example, for soliciting form input.
*
* To accomplish this, a ViewState returns a
* {@link ViewSelection}, which contains the logical name of a view template to
* render and all supporting model data needed to render it correctly. It is
* expected that some sort of view resolver will map this view selection to a
* renderable resource template (like a JSP file).
*
* A view state can also be a marker state with no associated view. In
* this case it just returns control back to the client. Marker states may be
* used for situations where an action or custom state type has already
* generated the response.
*
* @see org.springframework.webflow.ViewSelector
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class ViewState extends TransitionableState {
/**
* 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
*/
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;
}
/**
* Specialization of State's doEnter template method that
* executes behaviour specific to this state type in polymorphic fashion.
*
* Returns a view selection pointing callers to a logical view resource to
* be displayed. The view selection also contains a model map needed when
* the view is rendered, for populating dynamic content.
* @param context the control context for the currently executing flow, used
* by this state to manipulate the flow execution
* @return a view selection containing model and view information needed to
* render the results of the state execution
* @throws StateException if an exception occurs in this state
*/
protected ViewSelection doEnter(FlowExecutionControlContext context) throws StateException {
return viewSelector.makeSelection(context);
}
/**
* Request that the current view selection be reconstituted to support
* reissuing the response. This is idempotent operation that may be safely
* called on a paused execution, used primarily to support a flow execution
* redirect.
* @param context the request context
* @return the view selection
* @throws StateException if an exception occurs in this state
*/
public ViewSelection refresh(RequestContext context) throws StateException {
return viewSelector.makeRefreshSelection(context);
}
protected void appendToString(ToStringCreator creator) {
creator.append("viewSelector", viewSelector);
super.appendToString(creator);
}
}