org.springframework.webflow.engine.builder.FlowAssembler 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.util.Assert;
import org.springframework.webflow.core.collection.AttributeMap;
import org.springframework.webflow.core.collection.CollectionUtils;
import org.springframework.webflow.engine.Flow;
/**
* A director for assembling flows, delegating to a {@link FlowBuilder} to
* construct a flow. This class encapsulates the algorithm for using a
* FlowBuilder to assemble a Flow properly. It acts as the director in the
* classic GoF builder pattern.
*
* Flow assemblers may be used in a standalone, programmatic fashion as follows:
*
*
* FlowBuilder builder = ...;
* Flow flow = new FlowAssembler("myFlow", builder).assembleFlow();
*
*
* @see org.springframework.webflow.engine.builder.FlowBuilder
*
* @author Keith Donald
* @author Erwin Vervaet
*/
public class FlowAssembler {
/**
* The identifier to assign to the flow.
*/
private String flowId;
/**
* Attributes that can be used to affect flow construction.
*/
private AttributeMap flowAttributes;
/**
* The flow builder strategy used to construct the flow from its component
* parts.
*/
private FlowBuilder flowBuilder;
/**
* Create a new flow assembler that will direct Flow assembly using the
* specified builder strategy.
* @param flowId the flow id to assign
* @param flowBuilder the builder the factory will use to build flows
*/
public FlowAssembler(String flowId, FlowBuilder flowBuilder) {
this(flowId, null, flowBuilder);
}
/**
* Create a new flow assembler that will direct Flow assembly using the
* specified builder strategy.
* @param flowId the flow id to assign
* @param flowAttributes externally assigned flow attributes that can affect
* flow construction
* @param flowBuilder the builder the factory will use to build flows
*/
public FlowAssembler(String flowId, AttributeMap flowAttributes, FlowBuilder flowBuilder) {
Assert.hasText(flowId, "The flow id is required");
Assert.notNull(flowBuilder, "The flow builder is required");
this.flowId = flowId;
this.flowAttributes = (flowAttributes != null ? flowAttributes : CollectionUtils.EMPTY_ATTRIBUTE_MAP);
this.flowBuilder = flowBuilder;
}
/**
* Returns the identifier to assign to the flow.
*/
public String getFlowId() {
return flowId;
}
/**
* Returns externally assigned attributes that can be used to affect flow
* construction.
*/
public AttributeMap getFlowAttributes() {
return flowAttributes;
}
/**
* Returns the flow builder strategy used to construct the flow from its
* component parts.
*/
public FlowBuilder getFlowBuilder() {
return flowBuilder;
}
/**
* Assembles the flow, directing the construction process by delegating to
* the configured FlowBuilder. Every call to this method will assemble
* the Flow instance.
*
* This will drive the flow construction process as described in the
* {@link FlowBuilder} JavaDoc, starting with builder initialisation using
* {@link FlowBuilder#init(String, AttributeMap)} and finishing by
* cleaning up the builder with a call to {@link FlowBuilder#dispose()}.
* @return the constructed flow
* @throws FlowBuilderException when flow assembly fails
*/
public Flow assembleFlow() throws FlowBuilderException {
try {
flowBuilder.init(flowId, flowAttributes);
directAssembly();
return flowBuilder.getFlow();
}
finally {
flowBuilder.dispose();
}
}
/**
* Build all parts of the flow by directing flow assembly by the flow
* builder.
* @throws FlowBuilderException when flow assembly fails
*/
protected void directAssembly() throws FlowBuilderException {
flowBuilder.buildVariables();
flowBuilder.buildInputMapper();
flowBuilder.buildStartActions();
flowBuilder.buildInlineFlows();
flowBuilder.buildStates();
flowBuilder.buildGlobalTransitions();
flowBuilder.buildEndActions();
flowBuilder.buildOutputMapper();
flowBuilder.buildExceptionHandlers();
}
}