| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.datatorrent.lib.appdata.query.serde; |
| |
| import java.lang.annotation.Annotation; |
| import java.util.Map; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.Maps; |
| |
| import com.datatorrent.lib.appdata.schemas.Result; |
| import com.datatorrent.lib.appdata.schemas.ResultFormatter; |
| |
| /** |
| * This class simplifies serializing Messages. This is done by placing an annotation on the Message |
| * class which specifies the serializer for the class. Also another annotation is placed on the Message |
| * class to specify its type. An example is below: |
| * <br/> |
| * <br/> |
| * <pre> |
| * <code> |
| * {@literal @}MessageType(type=DataQueryDimensional.TYPE) |
| * {@literal @}MessageSerializerInfo(clazz=DataResultDimensionalSerializer.class) |
| * public class MyResultClass |
| * { |
| * ... |
| * } |
| * </code> |
| * </pre> |
| * Then this class can be deserialized by doing the following: |
| * <br/> |
| * <br/> |
| * <pre> |
| * <code> |
| * {@literal @}MyResultClass result; |
| * {@literal @}MessageSerializerFactory serializerFactory = new MessageSerializerFactory(new ResultFormatter()); |
| * ... |
| * String json = serializerFactory.serialize(result); |
| * } |
| * </code> |
| * </pre> |
| * @since 3.0.0 |
| */ |
| public class MessageSerializerFactory |
| { |
| private final Map<Class<? extends Result>, CustomMessageSerializer> clazzToCustomResultBuilder = Maps.newHashMap(); |
| private final Map<Class<? extends Result>, String> clazzToType = Maps.newHashMap(); |
| |
| private ResultFormatter resultFormatter = new ResultFormatter(); |
| |
| public MessageSerializerFactory(ResultFormatter resultFormatter) |
| { |
| setResultFormatter(resultFormatter); |
| } |
| |
| private void setResultFormatter(ResultFormatter resultFormatter) |
| { |
| this.resultFormatter = Preconditions.checkNotNull(resultFormatter); |
| } |
| |
| public ResultFormatter getResultFormatter() |
| { |
| return resultFormatter; |
| } |
| |
| public String serialize(Result result) |
| { |
| CustomMessageSerializer mcrs = clazzToCustomResultBuilder.get(result.getClass()); |
| Class<? extends Result> schema = result.getClass(); |
| |
| if (mcrs == null) { |
| Annotation[] ans = schema.getAnnotations(); |
| |
| Class<? extends CustomMessageSerializer> crs = null; |
| String type = null; |
| |
| for (Annotation an : ans) { |
| if (an instanceof MessageSerializerInfo) { |
| if (crs != null) { |
| throw new UnsupportedOperationException("Cannot specify the " + MessageSerializerInfo.class |
| + " annotation twice on the class: " + schema); |
| } |
| |
| crs = ((MessageSerializerInfo)an).clazz(); |
| } else if (an instanceof MessageType) { |
| if (type != null) { |
| throw new UnsupportedOperationException("Cannot specify the " + MessageType.class + |
| " annotation twice on the class: " + schema); |
| } |
| |
| type = ((MessageType)an).type(); |
| } |
| } |
| |
| if (crs == null) { |
| throw new UnsupportedOperationException("No " + MessageSerializerInfo.class + " annotation found on class: " |
| + schema); |
| } |
| |
| if (type == null) { |
| throw new UnsupportedOperationException("No " + MessageType.class + " annotation found on class " + schema); |
| } |
| |
| try { |
| mcrs = crs.newInstance(); |
| } catch (InstantiationException | IllegalAccessException ex) { |
| throw new RuntimeException(ex); |
| } |
| |
| clazzToCustomResultBuilder.put(schema, mcrs); |
| clazzToType.put(schema, type); |
| } |
| |
| result.setType(clazzToType.get(schema)); |
| |
| return mcrs.serialize(result, resultFormatter); |
| } |
| |
| private static final Logger LOG = LoggerFactory.getLogger(MessageSerializerFactory.class); |
| } |