Java tutorial
/* * Copyright (c) 2014 Hewlett-Packard Development Company, L.P. * * 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 monasca.api.infrastructure.persistence.influxdb; import com.google.inject.Inject; import org.apache.commons.codec.binary.Base64; import org.apache.http.Header; import org.apache.http.HeaderElement; import org.apache.http.HttpEntity; import org.apache.http.HttpException; import org.apache.http.HttpRequest; import org.apache.http.HttpRequestInterceptor; import org.apache.http.HttpResponse; import org.apache.http.HttpResponseInterceptor; import org.apache.http.HttpStatus; import org.apache.http.client.entity.GzipDecompressingEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.impl.conn.PoolingHttpClientConnectionManager; import org.apache.http.protocol.HttpContext; import org.apache.http.util.EntityUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.net.URLEncoder; import monasca.api.ApiConfig; public class InfluxV9RepoReader { private static final Logger logger = LoggerFactory.getLogger(InfluxV9RepoReader.class); private final String influxName; private final String influxUrl; private final String influxCreds; private final String influxUser; private final String influxPass; private final String baseAuthHeader; private final boolean gzip; private final CloseableHttpClient httpClient; @Inject public InfluxV9RepoReader(final ApiConfig config) { this.influxName = config.influxDB.getName(); logger.debug("Influxdb database name: {}", this.influxName); this.influxUrl = config.influxDB.getUrl() + "/query"; logger.debug("Influxdb URL: {}", this.influxUrl); this.influxUser = config.influxDB.getUser(); this.influxPass = config.influxDB.getPassword(); this.influxCreds = this.influxUser + ":" + this.influxPass; this.gzip = config.influxDB.getGzip(); logger.debug("Influxdb gzip responses: {}", this.gzip); logger.debug("Setting up basic Base64 authentication"); this.baseAuthHeader = "Basic " + new String(Base64.encodeBase64(this.influxCreds.getBytes())); // We inject InfluxV9RepoReader as a singleton. So, we must share connections safely. PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(); cm.setMaxTotal(config.influxDB.getMaxHttpConnections()); if (this.gzip) { logger.debug("Setting up gzip responses from Influxdb"); this.httpClient = HttpClients.custom().setConnectionManager(cm) .addInterceptorFirst(new HttpRequestInterceptor() { public void process(final HttpRequest request, final HttpContext context) throws HttpException, IOException { if (!request.containsHeader("Accept-Encoding")) { request.addHeader("Accept-Encoding", "gzip"); } } }).addInterceptorFirst(new HttpResponseInterceptor() { public void process(final HttpResponse response, final HttpContext context) throws HttpException, IOException { HttpEntity entity = response.getEntity(); if (entity != null) { Header ceheader = entity.getContentEncoding(); if (ceheader != null) { HeaderElement[] codecs = ceheader.getElements(); for (int i = 0; i < codecs.length; i++) { if (codecs[i].getName().equalsIgnoreCase("gzip")) { response.setEntity(new GzipDecompressingEntity(response.getEntity())); return; } } } } } }).build(); } else { logger.debug("Setting up non-gzip responses from Influxdb"); this.httpClient = HttpClients.custom().setConnectionManager(cm).build(); } } protected String read(final String query) throws Exception { HttpGet request = new HttpGet(this.influxUrl + "?q=" + URLEncoder.encode(query, "UTF-8") + "&db=" + URLEncoder.encode(this.influxName, "UTF-8")); request.addHeader("content-type", "application/json"); request.addHeader("Authorization", this.baseAuthHeader); try { logger.debug("Sending query {} to influx database {} at {}", query, this.influxName, this.influxUrl); HttpResponse response = this.httpClient.execute(request); int rc = response.getStatusLine().getStatusCode(); logger.debug("Received {} status code from influx database {} at {}", rc, this.influxName, this.influxUrl); if (rc != HttpStatus.SC_OK) { HttpEntity entity = response.getEntity(); String responseString = EntityUtils.toString(entity, "UTF-8"); logger.error("Failed to query influx database {} at {}: {}", this.influxName, this.influxUrl, String.valueOf(rc)); logger.error("Http response: {}", responseString); throw new Exception(rc + ":" + responseString); } logger.debug("Successfully queried influx database {} at {}", this.influxName, this.influxUrl); HttpEntity entity = response.getEntity(); return entity != null ? EntityUtils.toString(entity, "UTF-8") : null; } finally { request.releaseConnection(); } } }