Java tutorial
/* * Copyright 2010 Google Inc. * * 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 com.google.gwt.requestfactory.server; import com.google.gwt.autobean.server.AutoBeanFactoryMagic; import com.google.gwt.autobean.server.Configuration; import com.google.gwt.autobean.server.impl.TypeUtils; import com.google.gwt.autobean.shared.AutoBean; import com.google.gwt.autobean.shared.AutoBeanCodex; import com.google.gwt.autobean.shared.AutoBeanUtils; import com.google.gwt.autobean.shared.AutoBeanVisitor; import com.google.gwt.autobean.shared.Splittable; import com.google.gwt.autobean.shared.ValueCodex; import com.google.gwt.requestfactory.shared.BaseProxy; import com.google.gwt.requestfactory.shared.EntityProxyId; import com.google.gwt.requestfactory.shared.InstanceRequest; import com.google.gwt.requestfactory.shared.Request; import com.google.gwt.requestfactory.shared.ServerFailure; import com.google.gwt.requestfactory.shared.WriteOperation; import com.google.gwt.requestfactory.shared.impl.BaseProxyCategory; import com.google.gwt.requestfactory.shared.impl.Constants; import com.google.gwt.requestfactory.shared.impl.EntityCodex; import com.google.gwt.requestfactory.shared.impl.EntityProxyCategory; import com.google.gwt.requestfactory.shared.impl.SimpleProxyId; import com.google.gwt.requestfactory.shared.impl.ValueProxyCategory; import com.google.gwt.requestfactory.shared.messages.IdMessage.Strength; import com.google.gwt.requestfactory.shared.messages.InvocationMessage; import com.google.gwt.requestfactory.shared.messages.MessageFactory; import com.google.gwt.requestfactory.shared.messages.OperationMessage; import com.google.gwt.requestfactory.shared.messages.RequestMessage; import com.google.gwt.requestfactory.shared.messages.ResponseMessage; import com.google.gwt.requestfactory.shared.messages.ServerFailureMessage; import com.google.gwt.requestfactory.shared.messages.ViolationMessage; import com.google.gwt.user.server.Base64Utils; import java.io.UnsupportedEncodingException; import java.lang.reflect.Method; import java.lang.reflect.Type; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import java.util.Set; import javax.validation.ConstraintViolation; /** * Processes request payloads from a RequestFactory client. This implementation * is stateless. A single instance may be reused and is thread-safe. * * <p><span style='color:red'>RequestFactory has moved to * <code>com.google.web.bindery.requestfactory</code>. This package will be * removed in a future version of GWT.</span></p> */ @Deprecated public class SimpleRequestProcessor { /** * This parameterization is so long, it improves readability to have a * specific type. * * <p><span style='color:red'>RequestFactory has moved to * <code>com.google.web.bindery.requestfactory</code>. This package will be * removed in a future version of GWT.</span></p> */ @Deprecated @SuppressWarnings("serial") static class IdToEntityMap extends HashMap<SimpleProxyId<?>, AutoBean<? extends BaseProxy>> { } /** * Allows the creation of properly-configured AutoBeans without having to * create an AutoBeanFactory with the desired annotations. */ static final Configuration CONFIGURATION = new Configuration.Builder() .setCategories(EntityProxyCategory.class, ValueProxyCategory.class, BaseProxyCategory.class) .setNoWrap(EntityProxyId.class).build(); /** * Vends message objects. */ static final MessageFactory FACTORY = AutoBeanFactoryMagic.create(MessageFactory.class); static String fromBase64(String encoded) { try { return new String(Base64Utils.fromBase64(encoded), "UTF-8"); } catch (UnsupportedEncodingException e) { throw new UnexpectedException(e); } } static String toBase64(String data) { try { return Base64Utils.toBase64(data.getBytes("UTF-8")); } catch (UnsupportedEncodingException e) { throw new UnexpectedException(e); } } private ExceptionHandler exceptionHandler = new DefaultExceptionHandler(); private final ServiceLayer service; public SimpleRequestProcessor(ServiceLayer serviceLayer) { this.service = serviceLayer; } /** * Process a payload sent by a RequestFactory client. * * @param payload the payload sent by the client * @return a payload to return to the client */ public String process(String payload) { RequestMessage req = AutoBeanCodex.decode(FACTORY, RequestMessage.class, payload).as(); AutoBean<ResponseMessage> responseBean = FACTORY.response(); try { process(req, responseBean.as()); } catch (ReportableException e) { e.printStackTrace(); // Create a new response envelope, since the state is unknown responseBean = FACTORY.response(); responseBean.as().setGeneralFailure(createFailureMessage(e).as()); } // Return a JSON-formatted payload return AutoBeanCodex.encode(responseBean).getPayload(); } public void setExceptionHandler(ExceptionHandler exceptionHandler) { this.exceptionHandler = exceptionHandler; } /** * Encode a list of objects into a self-contained message that can be used for * out-of-band communication. */ <T> Splittable createOobMessage(List<T> domainValues) { RequestState state = new RequestState(service); List<Splittable> encodedValues = new ArrayList<Splittable>(domainValues.size()); for (T domainValue : domainValues) { Object clientValue; if (domainValue == null) { clientValue = null; } else { Class<?> clientType = service.resolveClientType(domainValue.getClass(), BaseProxy.class, true); clientValue = state.getResolver().resolveClientValue(domainValue, clientType, Collections.<String>emptySet()); } encodedValues.add(EntityCodex.encode(state, clientValue)); } IdToEntityMap map = new IdToEntityMap(); map.putAll(state.beans); List<OperationMessage> operations = new ArrayList<OperationMessage>(); createReturnOperations(operations, state, map); InvocationMessage invocation = FACTORY.invocation().as(); invocation.setParameters(encodedValues); AutoBean<RequestMessage> bean = FACTORY.request(); RequestMessage resp = bean.as(); resp.setInvocations(Collections.singletonList(invocation)); resp.setOperations(operations); return AutoBeanCodex.encode(bean); } /** * Decode an out-of-band message. */ <T> List<T> decodeOobMessage(Class<T> domainClass, Splittable payload) { Class<?> proxyType = service.resolveClientType(domainClass, BaseProxy.class, true); RequestState state = new RequestState(service); RequestMessage message = AutoBeanCodex.decode(FACTORY, RequestMessage.class, payload).as(); processOperationMessages(state, message); List<Object> decoded = decodeInvocationArguments(state, message.getInvocations().get(0).getParameters(), new Class<?>[] { proxyType }, new Type[] { domainClass }); @SuppressWarnings("unchecked") List<T> toReturn = (List<T>) decoded; return toReturn; } /** * Main processing method. */ void process(RequestMessage req, ResponseMessage resp) { final RequestState source = new RequestState(service); // Apply operations processOperationMessages(source, req); // Validate entities List<ViolationMessage> errorMessages = validateEntities(source); if (!errorMessages.isEmpty()) { resp.setViolations(errorMessages); return; } RequestState returnState = new RequestState(source); // Invoke methods List<Splittable> invocationResults = new ArrayList<Splittable>(); List<Boolean> invocationSuccess = new ArrayList<Boolean>(); processInvocationMessages(source, req, invocationResults, invocationSuccess, returnState); // Store return objects List<OperationMessage> operations = new ArrayList<OperationMessage>(); IdToEntityMap toProcess = new IdToEntityMap(); toProcess.putAll(source.beans); toProcess.putAll(returnState.beans); createReturnOperations(operations, returnState, toProcess); assert invocationResults.size() == invocationSuccess.size(); if (!invocationResults.isEmpty()) { resp.setInvocationResults(invocationResults); resp.setStatusCodes(invocationSuccess); } if (!operations.isEmpty()) { resp.setOperations(operations); } } private AutoBean<ServerFailureMessage> createFailureMessage(ReportableException e) { ServerFailure failure = exceptionHandler.createServerFailure(e.getCause() == null ? e : e.getCause()); AutoBean<ServerFailureMessage> bean = FACTORY.failure(); ServerFailureMessage msg = bean.as(); msg.setExceptionType(failure.getExceptionType()); msg.setMessage(failure.getMessage()); msg.setStackTrace(failure.getStackTraceString()); msg.setFatal(failure.isFatal()); return bean; } private void createReturnOperations(List<OperationMessage> operations, RequestState returnState, IdToEntityMap toProcess) { for (Map.Entry<SimpleProxyId<?>, AutoBean<? extends BaseProxy>> entry : toProcess.entrySet()) { SimpleProxyId<?> id = entry.getKey(); AutoBean<? extends BaseProxy> bean = entry.getValue(); Object domainObject = bean.getTag(Constants.DOMAIN_OBJECT); WriteOperation writeOperation; if (id.isEphemeral()) { // See if the entity has been persisted in the meantime returnState.getResolver().resolveClientValue(domainObject, id.getProxyClass(), Collections.<String>emptySet()); } if (id.isEphemeral() || id.isSynthetic() || domainObject == null) { // If the object isn't persistent, there's no reason to send an update writeOperation = null; } else if (!service.isLive(domainObject)) { writeOperation = WriteOperation.DELETE; } else if (id.wasEphemeral()) { writeOperation = WriteOperation.PERSIST; } else { writeOperation = WriteOperation.UPDATE; } Splittable version = null; if (writeOperation == WriteOperation.PERSIST || writeOperation == WriteOperation.UPDATE) { /* * If we're sending an operation, the domain object must be persistent. * This means that it must also have a non-null version. */ Object domainVersion = service.getVersion(domainObject); if (domainVersion == null) { throw new UnexpectedException( "The persisted entity with id " + service.getId(domainObject) + " has a null version", null); } version = returnState.flatten(domainVersion); } boolean inResponse = bean.getTag(Constants.IN_RESPONSE) != null; /* * Don't send any data back to the client for an update on an object that * isn't part of the response payload when the client's version matches * the domain version. */ if (WriteOperation.UPDATE.equals(writeOperation) && !inResponse) { String previousVersion = bean.<String>getTag(Constants.VERSION_PROPERTY_B64); if (version != null && previousVersion != null && version.equals(fromBase64(previousVersion))) { continue; } } OperationMessage op = FACTORY.operation().as(); /* * Send a client id if the id is ephemeral or was previously associated * with a client id. */ if (id.wasEphemeral()) { op.setClientId(id.getClientId()); } op.setOperation(writeOperation); // Only send properties for entities that are part of the return graph if (inResponse) { Map<String, Splittable> propertyMap = new LinkedHashMap<String, Splittable>(); // Add all non-null properties to the serialized form Map<String, Object> diff = AutoBeanUtils.getAllProperties(bean); for (Map.Entry<String, Object> d : diff.entrySet()) { Object value = d.getValue(); if (value != null) { propertyMap.put(d.getKey(), EntityCodex.encode(returnState, value)); } } op.setPropertyMap(propertyMap); } if (!id.isEphemeral() && !id.isSynthetic()) { // Send the server address only for persistent objects op.setServerId(toBase64(id.getServerId())); } if (id.isSynthetic()) { op.setStrength(Strength.SYNTHETIC); op.setSyntheticId(id.getSyntheticId()); } else if (id.isEphemeral()) { op.setStrength(Strength.EPHEMERAL); } op.setTypeToken(service.resolveTypeToken(id.getProxyClass())); if (version != null) { op.setVersion(toBase64(version.getPayload())); } operations.add(op); } } /** * Decode the arguments to pass into the domain method. If the domain method * is not static, the instance object will be in the 0th position. */ private List<Object> decodeInvocationArguments(RequestState source, InvocationMessage invocation, Method contextMethod) { boolean isStatic = Request.class.isAssignableFrom(contextMethod.getReturnType()); int baseLength = contextMethod.getParameterTypes().length; int length = baseLength + (isStatic ? 0 : 1); int offset = isStatic ? 0 : 1; Class<?>[] contextArgs = new Class<?>[length]; Type[] genericArgs = new Type[length]; if (!isStatic) { genericArgs[0] = TypeUtils.getSingleParameterization(InstanceRequest.class, contextMethod.getGenericReturnType()); contextArgs[0] = TypeUtils.ensureBaseType(genericArgs[0]); } System.arraycopy(contextMethod.getParameterTypes(), 0, contextArgs, offset, baseLength); System.arraycopy(contextMethod.getGenericParameterTypes(), 0, genericArgs, offset, baseLength); List<Object> args = decodeInvocationArguments(source, invocation.getParameters(), contextArgs, genericArgs); return args; } /** * Handles instance invocations as the instance at the 0th parameter. */ private List<Object> decodeInvocationArguments(RequestState source, List<Splittable> parameters, Class<?>[] contextArgs, Type[] genericArgs) { if (parameters == null) { // Can't return Collections.emptyList() because this must be mutable return new ArrayList<Object>(); } assert parameters.size() == contextArgs.length; List<Object> args = new ArrayList<Object>(contextArgs.length); for (int i = 0, j = contextArgs.length; i < j; i++) { Class<?> type = contextArgs[i]; Class<?> elementType = null; Splittable split; if (Collection.class.isAssignableFrom(type)) { elementType = TypeUtils .ensureBaseType(TypeUtils.getSingleParameterization(Collection.class, genericArgs[i])); split = parameters.get(i); } else { split = parameters.get(i); } Object arg = EntityCodex.decode(source, type, elementType, split); arg = source.getResolver().resolveDomainValue(arg, !EntityProxyId.class.equals(contextArgs[i])); args.add(arg); } return args; } private void processInvocationMessages(RequestState state, RequestMessage req, List<Splittable> results, List<Boolean> success, RequestState returnState) { List<InvocationMessage> invocations = req.getInvocations(); if (invocations == null) { // No method invocations which can happen via RequestContext.fire() return; } for (InvocationMessage invocation : invocations) { try { // Find the Method String[] operation = invocation.getOperation().split("::"); Method contextMethod = service.resolveRequestContextMethod(operation[0], operation[1]); if (contextMethod == null) { throw new UnexpectedException("Cannot resolve operation " + invocation.getOperation(), null); } Method domainMethod = service.resolveDomainMethod(contextMethod); if (domainMethod == null) { throw new UnexpectedException("Cannot resolve domain method " + invocation.getOperation(), null); } // Compute the arguments List<Object> args = decodeInvocationArguments(state, invocation, contextMethod); // Possibly use a ServiceLocator if (service.requiresServiceLocator(contextMethod, domainMethod)) { Object serviceInstance = service.createServiceInstance(contextMethod, domainMethod); args.add(0, serviceInstance); } // Invoke it Object returnValue = service.invoke(domainMethod, args.toArray()); // Convert domain object to client object Type requestReturnType = service.getRequestReturnType(contextMethod); returnValue = state.getResolver().resolveClientValue(returnValue, requestReturnType, invocation.getPropertyRefs()); // Convert the client object to a string results.add(EntityCodex.encode(returnState, returnValue)); success.add(true); } catch (ReportableException e) { results.add(AutoBeanCodex.encode(createFailureMessage(e))); success.add(false); } } } private void processOperationMessages(final RequestState state, RequestMessage req) { List<OperationMessage> operations = req.getOperations(); if (operations == null) { return; } List<AutoBean<? extends BaseProxy>> beans = state.getBeansForPayload(operations); assert operations.size() == beans.size(); Iterator<OperationMessage> itOp = operations.iterator(); for (AutoBean<? extends BaseProxy> bean : beans) { OperationMessage operation = itOp.next(); // Save the client's version information to reduce payload size later bean.setTag(Constants.VERSION_PROPERTY_B64, operation.getVersion()); // Load the domain object with properties, if it exists final Object domain = bean.getTag(Constants.DOMAIN_OBJECT); if (domain != null) { // Apply any property updates final Map<String, Splittable> flatValueMap = operation.getPropertyMap(); if (flatValueMap != null) { bean.accept(new AutoBeanVisitor() { @Override public boolean visitReferenceProperty(String propertyName, AutoBean<?> value, PropertyContext ctx) { // containsKey to distinguish null from unknown if (flatValueMap.containsKey(propertyName)) { Class<?> elementType = ctx instanceof CollectionPropertyContext ? ((CollectionPropertyContext) ctx).getElementType() : null; Object newValue = EntityCodex.decode(state, ctx.getType(), elementType, flatValueMap.get(propertyName)); Object resolved = state.getResolver().resolveDomainValue(newValue, false); service.setProperty(domain, propertyName, service.resolveDomainClass(ctx.getType()), resolved); } return false; } @Override public boolean visitValueProperty(String propertyName, Object value, PropertyContext ctx) { if (flatValueMap.containsKey(propertyName)) { Splittable split = flatValueMap.get(propertyName); Object newValue = ValueCodex.decode(ctx.getType(), split); Object resolved = state.getResolver().resolveDomainValue(newValue, false); service.setProperty(domain, propertyName, ctx.getType(), resolved); } return false; } }); } } } } /** * Validate all of the entities referenced in a RequestState. */ private List<ViolationMessage> validateEntities(RequestState source) { List<ViolationMessage> errorMessages = new ArrayList<ViolationMessage>(); for (Map.Entry<SimpleProxyId<?>, AutoBean<? extends BaseProxy>> entry : source.beans.entrySet()) { AutoBean<? extends BaseProxy> bean = entry.getValue(); Object domainObject = bean.getTag(Constants.DOMAIN_OBJECT); // The object could have been deleted if (domainObject != null) { Set<ConstraintViolation<Object>> errors = service.validate(domainObject); if (errors != null && !errors.isEmpty()) { SimpleProxyId<?> id = entry.getKey(); for (ConstraintViolation<Object> error : errors) { ViolationMessage message = FACTORY.violation().as(); message.setClientId(id.getClientId()); message.setMessage(error.getMessage()); message.setPath(error.getPropertyPath().toString()); if (id.isEphemeral()) { message.setClientId(id.getClientId()); message.setStrength(Strength.EPHEMERAL); } else { message.setServerId(toBase64(id.getServerId())); } message.setTypeToken(service.resolveTypeToken(id.getProxyClass())); errorMessages.add(message); } } } } return errorMessages; } }