org.springframework.webflow.engine.builder.TextToViewSelector 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.engine.builder;
import org.springframework.binding.convert.ConversionContext;
import org.springframework.binding.convert.support.ConversionServiceAwareConverter;
import org.springframework.binding.expression.Expression;
import org.springframework.util.StringUtils;
import org.springframework.webflow.engine.NullViewSelector;
import org.springframework.webflow.engine.ViewSelector;
import org.springframework.webflow.engine.support.ApplicationViewSelector;
import org.springframework.webflow.engine.support.ExternalRedirectSelector;
import org.springframework.webflow.engine.support.FlowDefinitionRedirectSelector;
import org.springframework.webflow.execution.support.ApplicationView;
import org.springframework.webflow.execution.support.ExternalRedirect;
import org.springframework.webflow.execution.support.FlowDefinitionRedirect;
import org.springframework.webflow.execution.support.FlowExecutionRedirect;
/**
* Converter that converts an encoded string representation of a view selector
* into a {@link ViewSelector} object that will make selections at runtime.
*
* This converter supports the following encoded forms:
*
* - empty - will result in a {@link NullViewSelector}.
* - "viewName" - will result in an {@link ApplicationViewSelector} that
* returns an {@link ApplicationView} ViewSelection with the provided view name expression.
* - "redirect:<viewName>" - will result in an
* {@link ApplicationViewSelector} that returns an {@link FlowExecutionRedirect}
* to a flow execution URL.
* - "externalRedirect:<url>" - will result in an
* {@link ExternalRedirectSelector} that returns an {@link ExternalRedirect} to a
* URL.
* - "flowRedirect:<flowId>" - will result in a
* {@link FlowDefinitionRedirectSelector} that returns a {@link FlowDefinitionRedirect}
* to a flow.
* - "bean:<id>" - will result in usage of a custom
*
ViewSelector bean implementation.
*
*
* @see org.springframework.webflow.execution.ViewSelection
* @see org.springframework.webflow.engine.ViewSelector
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class TextToViewSelector extends ConversionServiceAwareConverter {
/**
* Prefix used when the encoded view name wants to specify that a redirect
* is required. ("redirect:")
*/
public static final String REDIRECT_PREFIX = "redirect:";
/**
* Prefix used when the encoded view name wants to specify that a redirect
* to an external URL is required. ("externalRedirect:")
*/
public static final String EXTERNAL_REDIRECT_PREFIX = "externalRedirect:";
/**
* Prefix used when the encoded view name wants to specify that a redirect
* to a flow definition is requred. ("flowRedirect:")
*/
public static final String FLOW_DEFINITION_REDIRECT_PREFIX = "flowRedirect:";
/**
* Prefix used when the user wants to use a ViewSelector implementation
* managed by a bean factory. ("bean:")
*/
private static final String BEAN_PREFIX = "bean:";
/**
* Locator to use for loading custom ViewSelector beans.
*/
private FlowServiceLocator flowServiceLocator;
/**
* Create a new text to ViewSelector converter. Custom ViewSelector implemenations
* will be looked up using given service locator.
*/
public TextToViewSelector(FlowServiceLocator flowServiceLocator) {
this.flowServiceLocator = flowServiceLocator;
setConversionService(flowServiceLocator.getConversionService());
}
public Class[] getSourceClasses() {
return new Class[] { String.class };
}
public Class[] getTargetClasses() {
return new Class[] { ViewSelector.class };
}
protected Object doConvert(Object source, Class targetClass, ConversionContext context) throws Exception {
String encodedView = (String)source;
if (!StringUtils.hasText(encodedView)) {
return NullViewSelector.INSTANCE;
}
else {
return convertEncodedViewSelector(encodedView);
}
}
/**
* Convert given encoded view into an appropriate view selector.
* @param encodedView the encoded view selector
* @return the view selector
*/
protected ViewSelector convertEncodedViewSelector(String encodedView) {
if (encodedView.startsWith(REDIRECT_PREFIX)) {
String viewName = encodedView.substring(REDIRECT_PREFIX.length());
Expression viewNameExpr = (Expression)fromStringTo(Expression.class).execute(viewName);
// just show the application view using a redirect
return new ApplicationViewSelector(viewNameExpr, true);
}
else if (encodedView.startsWith(EXTERNAL_REDIRECT_PREFIX)) {
String externalUrl = encodedView.substring(EXTERNAL_REDIRECT_PREFIX.length());
Expression urlExpr = (Expression)fromStringTo(Expression.class).execute(externalUrl);
return new ExternalRedirectSelector(urlExpr);
}
else if (encodedView.startsWith(FLOW_DEFINITION_REDIRECT_PREFIX)) {
String flowRedirect = encodedView.substring(FLOW_DEFINITION_REDIRECT_PREFIX.length());
Expression redirectExpr = (Expression)fromStringTo(Expression.class).execute(flowRedirect);
return new FlowDefinitionRedirectSelector(redirectExpr);
}
else if (encodedView.startsWith(BEAN_PREFIX)) {
String id = encodedView.substring(BEAN_PREFIX.length());
return flowServiceLocator.getViewSelector(id);
}
else {
Expression viewNameExpr = (Expression)fromStringTo(Expression.class).execute(encodedView);
return new ApplicationViewSelector(viewNameExpr);
}
}
}