Java tutorial
/* * 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 * * 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.apache.streams.facebook.processor; import com.fasterxml.jackson.core.JsonParseException; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ObjectNode; import com.google.common.collect.Lists; import org.apache.streams.core.StreamsDatum; import org.apache.streams.core.StreamsProcessor; import org.apache.streams.exceptions.ActivitySerializerException; import org.apache.streams.facebook.Page; import org.apache.streams.facebook.Post; import org.apache.streams.facebook.api.FacebookPageActivitySerializer; import org.apache.streams.facebook.api.FacebookPostActivitySerializer; import org.apache.streams.facebook.provider.FacebookEventClassifier; import org.apache.streams.jackson.StreamsJacksonMapper; import org.apache.streams.pojo.json.Activity; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.util.List; import java.util.Queue; public class FacebookTypeConverter implements StreamsProcessor { public final static String STREAMS_ID = "FacebookTypeConverter"; private final static Logger LOGGER = LoggerFactory.getLogger(FacebookTypeConverter.class); private ObjectMapper mapper; private Queue<StreamsDatum> inQueue; private Queue<StreamsDatum> outQueue; private Class inClass; private Class outClass; private FacebookPostActivitySerializer facebookPostActivitySerializer; private FacebookPageActivitySerializer facebookPageActivitySerializer; private int count = 0; public final static String TERMINATE = new String("TERMINATE"); public FacebookTypeConverter(Class inClass, Class outClass) { this.inClass = inClass; this.outClass = outClass; } public Queue<StreamsDatum> getProcessorOutputQueue() { return outQueue; } public void setProcessorInputQueue(Queue<StreamsDatum> inputQueue) { inQueue = inputQueue; } public Object convert(ObjectNode event, Class inClass, Class outClass) throws ActivitySerializerException, JsonProcessingException { Object result = null; if (outClass.equals(Activity.class)) { LOGGER.debug("ACTIVITY"); if (inClass.equals(Post.class)) { LOGGER.debug("POST"); result = facebookPostActivitySerializer.deserialize(mapper.convertValue(event, Post.class)); } else if (inClass.equals(Page.class)) { LOGGER.debug("PAGE"); result = facebookPageActivitySerializer.deserialize(mapper.convertValue(event, Page.class)); } } else if (outClass.equals(Post.class)) { LOGGER.debug("POST"); result = mapper.convertValue(event, Post.class); } else if (outClass.equals(Page.class)) { LOGGER.debug("PAGE"); result = mapper.convertValue(event, Page.class); } else if (outClass.equals(ObjectNode.class)) { LOGGER.debug("OBJECTNODE"); result = mapper.convertValue(event, ObjectNode.class); } // no supported conversion were applied if (result != null) { count++; return result; } LOGGER.debug("CONVERT FAILED"); return null; } public boolean validate(Object document, Class klass) { // TODO return true; } public boolean isValidJSON(final String json) { boolean valid = false; try { final JsonParser parser = new ObjectMapper().getJsonFactory().createJsonParser(json); while (parser.nextToken() != null) { } valid = true; } catch (JsonParseException jpe) { LOGGER.warn("validate: {}", jpe); } catch (IOException ioe) { LOGGER.warn("validate: {}", ioe); } return valid; } @Override public List<StreamsDatum> process(StreamsDatum entry) { StreamsDatum result = null; try { Object item = entry.getDocument(); ObjectNode node; LOGGER.debug("{} processing {}", STREAMS_ID, item.getClass()); if (item instanceof String) { // if the target is string, just pass-through if (String.class.equals(outClass)) { result = entry; } else { // first check for valid json node = (ObjectNode) mapper.readTree((String) item); // since data is coming from outside provider, we don't know what type the events are // for now we'll assume post Class inClass = FacebookEventClassifier.detectClass((String) item); Object out = convert(node, inClass, outClass); if (out != null && validate(out, outClass)) result = new StreamsDatum(out); } } else if (item instanceof ObjectNode) { // first check for valid json node = (ObjectNode) mapper.valueToTree(item); Class inClass = FacebookEventClassifier.detectClass(mapper.writeValueAsString(item)); Object out = convert(node, inClass, outClass); if (out != null && validate(out, outClass)) result = new StreamsDatum(out); } else if (item instanceof Post || item instanceof Page) { Object out = convert(mapper.convertValue(item, ObjectNode.class), inClass, outClass); if (out != null && validate(out, outClass)) result = new StreamsDatum(out); } } catch (Exception e) { LOGGER.error("Exception switching types : {}", e); if (e instanceof InterruptedException) { Thread.currentThread().interrupt(); } } if (result != null) return Lists.newArrayList(result); else return Lists.newArrayList(); } @Override public void prepare(Object o) { mapper = StreamsJacksonMapper.getInstance(); facebookPageActivitySerializer = new FacebookPageActivitySerializer(); facebookPostActivitySerializer = new FacebookPostActivitySerializer(); } @Override public void cleanUp() { } }