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.components.http.processor; import org.apache.streams.components.http.HttpProcessorConfiguration; import org.apache.streams.config.ComponentConfigurator; import org.apache.streams.config.StreamsConfigurator; import org.apache.streams.core.StreamsDatum; import org.apache.streams.core.StreamsProcessor; import org.apache.streams.jackson.StreamsJacksonMapper; import org.apache.streams.pojo.extensions.ExtensionUtil; import org.apache.streams.pojo.json.ActivityObject; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ObjectNode; import org.apache.commons.codec.binary.Base64; import org.apache.commons.lang3.StringUtils; import org.apache.http.HttpEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.utils.URIBuilder; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.net.URI; import java.net.URISyntaxException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * Processor retrieves contents from an known url and stores the resulting object in an extension field. */ public class SimpleHTTPGetProcessor implements StreamsProcessor { private static final String STREAMS_ID = "SimpleHTTPGetProcessor"; // from root config id private static final String EXTENSION = "account_type"; private static final Logger LOGGER = LoggerFactory.getLogger(SimpleHTTPGetProcessor.class); protected ObjectMapper mapper; protected URIBuilder uriBuilder; protected CloseableHttpClient httpclient; protected HttpProcessorConfiguration configuration; protected String authHeader; /** * SimpleHTTPGetProcessor constructor - resolves HttpProcessorConfiguration from JVM 'http'. */ public SimpleHTTPGetProcessor() { this(new ComponentConfigurator<>(HttpProcessorConfiguration.class) .detectConfiguration(StreamsConfigurator.getConfig().getConfig("http"))); } /** * SimpleHTTPGetProcessor constructor - uses provided HttpProcessorConfiguration. */ public SimpleHTTPGetProcessor(HttpProcessorConfiguration processorConfiguration) { LOGGER.info("creating SimpleHTTPGetProcessor"); LOGGER.info(processorConfiguration.toString()); this.configuration = processorConfiguration; } @Override public String getId() { return STREAMS_ID; } /** Override this to store a result other than exact json representation of response. */ protected ObjectNode prepareExtensionFragment(String entityString) { try { return mapper.readValue(entityString, ObjectNode.class); } catch (IOException ex) { LOGGER.warn(ex.getMessage()); return null; } } /** Override this to place result in non-standard location on document. */ protected ObjectNode getRootDocument(StreamsDatum datum) { try { String json = datum.getDocument() instanceof String ? (String) datum.getDocument() : mapper.writeValueAsString(datum.getDocument()); return mapper.readValue(json, ObjectNode.class); } catch (IOException ex) { LOGGER.warn(ex.getMessage()); return null; } } /** Override this to place result in non-standard location on document. */ protected ActivityObject getEntityToExtend(ObjectNode rootDocument) { if (this.configuration.getEntity().equals(HttpProcessorConfiguration.Entity.ACTIVITY)) { return mapper.convertValue(rootDocument, ActivityObject.class); } else { return mapper.convertValue(rootDocument.get(this.configuration.getEntity().toString()), ActivityObject.class); } } /** Override this to place result in non-standard location on document. */ protected ObjectNode setEntityToExtend(ObjectNode rootDocument, ActivityObject activityObject) { if (this.configuration.getEntity().equals(HttpProcessorConfiguration.Entity.ACTIVITY)) { return mapper.convertValue(activityObject, ObjectNode.class); } else { rootDocument.set(this.configuration.getEntity().toString(), mapper.convertValue(activityObject, ObjectNode.class)); } return rootDocument; } @Override public List<StreamsDatum> process(StreamsDatum entry) { List<StreamsDatum> result = new ArrayList<>(); ObjectNode rootDocument = getRootDocument(entry); Map<String, String> params = prepareParams(entry); URI uri = prepareURI(params); HttpGet httpget = prepareHttpGet(uri); CloseableHttpResponse response = null; String entityString = null; try { response = httpclient.execute(httpget); HttpEntity entity = response.getEntity(); // TODO: handle retry if (response.getStatusLine().getStatusCode() == 200 && entity != null) { entityString = EntityUtils.toString(entity); } } catch (IOException ex) { LOGGER.error("IO error:\n{}\n{}\n{}", uri.toString(), response, ex.getMessage()); return result; } finally { try { if (response != null) { response.close(); } } catch (IOException ignored) { LOGGER.trace("IOException", ignored); } } if (entityString == null) { return result; } LOGGER.debug(entityString); ObjectNode extensionFragment = prepareExtensionFragment(entityString); ActivityObject extensionEntity = getEntityToExtend(rootDocument); ExtensionUtil.getInstance().addExtension(extensionEntity, this.configuration.getExtension(), extensionFragment); rootDocument = setEntityToExtend(rootDocument, extensionEntity); entry.setDocument(rootDocument); result.add(entry); return result; } /** Override this to alter request URI. */ protected URI prepareURI(Map<String, String> params) { URI uri = null; for (Map.Entry<String, String> param : params.entrySet()) { uriBuilder = uriBuilder.setParameter(param.getKey(), param.getValue()); } try { uri = uriBuilder.build(); } catch (URISyntaxException ex) { LOGGER.error("URI error {}", uriBuilder.toString()); } return uri; } /** Override this to add parameters to the request. */ protected Map<String, String> prepareParams(StreamsDatum entry) { return new HashMap<>(); } /** Override this to set a payload on the request. */ protected ObjectNode preparePayload(StreamsDatum entry) { return null; } /** * Override this to set the URI for the request or modify headers. * @param uri uri * @return result */ public HttpGet prepareHttpGet(URI uri) { HttpGet httpget = new HttpGet(uri); httpget.addHeader("content-type", this.configuration.getContentType()); if (StringUtils.isNotBlank(authHeader)) { httpget.addHeader("Authorization", String.format("Basic %s", authHeader)); } return httpget; } @Override public void prepare(Object configurationObject) { mapper = StreamsJacksonMapper.getInstance(); uriBuilder = new URIBuilder().setScheme(this.configuration.getProtocol()) .setHost(this.configuration.getHostname()).setPath(this.configuration.getResourcePath()); if (StringUtils.isNotBlank(configuration.getAccessToken())) { uriBuilder = uriBuilder.addParameter("access_token", configuration.getAccessToken()); } if (StringUtils.isNotBlank(configuration.getUsername()) && StringUtils.isNotBlank(configuration.getPassword())) { String string = configuration.getUsername() + ":" + configuration.getPassword(); authHeader = Base64.encodeBase64String(string.getBytes()); } httpclient = HttpClients.createDefault(); } @Override public void cleanUp() { LOGGER.info("shutting down SimpleHTTPGetProcessor"); try { httpclient.close(); } catch (IOException ex) { ex.printStackTrace(); } finally { try { httpclient.close(); } catch (IOException e2) { e2.printStackTrace(); } finally { httpclient = null; } } } }