001    /**
002     * Copyright 2005-2013 The Kuali Foundation
003     *
004     * Licensed under the Educational Community License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     * http://www.opensource.org/licenses/ecl2.php
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */
016    package org.kuali.rice.kew.validation;
017    
018    import org.apache.commons.lang.StringUtils;
019    import org.kuali.rice.kew.api.WorkflowRuntimeException;
020    import org.kuali.rice.kew.api.validation.RuleValidationContext;
021    import org.kuali.rice.kew.api.validation.ValidationResults;
022    import org.kuali.rice.kew.framework.KewFrameworkServiceLocator;
023    import org.kuali.rice.kew.framework.validation.RuleValidationAttributeExporterService;
024    import org.kuali.rice.kew.rule.RuleValidationAttribute;
025    
026    import java.lang.reflect.InvocationHandler;
027    import java.lang.reflect.Method;
028    import java.lang.reflect.Proxy;
029    
030    /**
031     * RuleValidationAttributeResolver reference impl.  Returns a proxy which delegates to the appropriate
032     * RuleValidationExporterService.
033     *
034     * @see org.kuali.rice.kew.rule.RuleValidationAttribute
035     * @see org.kuali.rice.kew.framework.validation.RuleValidationAttributeExporterService
036     * @author Kuali Rice Team (rice.collab@kuali.org)
037     */
038    public class RuleValidationAttributeResolverImpl implements RuleValidationAttributeResolver {
039        @Override
040        public RuleValidationAttribute resolveRuleValidationAttribute(final String attributeName, String applicationId) throws Exception {
041            final RuleValidationAttributeExporterService service = findRuleValidationAttributeExporterService(applicationId);
042            return (RuleValidationAttribute) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class<?>[] { RuleValidationAttribute.class }, new RuleValidationAttributeInvocationHandler() {
043                @Override
044                protected ValidationResults invokeValidate(RuleValidationContext context) throws Exception {
045                    return service.validate(attributeName, context);
046                }
047            });
048        }
049    
050        protected RuleValidationAttributeExporterService findRuleValidationAttributeExporterService(String applicationId) {
051            RuleValidationAttributeExporterService service = KewFrameworkServiceLocator.getRuleValidationAttributeExporterService(applicationId);
052            if (service == null) {
053                throw new WorkflowRuntimeException("Failed to locate RuleValidationAttributeExporterService for applicationId: " + applicationId);
054            }
055            return service;
056        }
057    
058        protected static abstract class RuleValidationAttributeInvocationHandler implements InvocationHandler {
059            @Override
060            public ValidationResults invoke(Object o, Method method, Object[] objects) throws Throwable {
061                if (!StringUtils.equals(method.getName(), "validate")) {
062                    throw new UnsupportedOperationException("RuleValidationAttribute only supports 'validate'");
063                }
064                return invokeValidate((RuleValidationContext) objects[0]);
065            }
066            protected abstract ValidationResults invokeValidate(RuleValidationContext context) throws Exception;
067        }
068    }