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.neo4j.http; import org.apache.streams.neo4j.Neo4jConfiguration; import org.apache.http.client.HttpClient; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.Map; import java.util.Objects; import java.util.concurrent.ConcurrentHashMap; import static org.hamcrest.MatcherAssert.assertThat; public class Neo4jHttpClient { private static final Logger LOGGER = LoggerFactory.getLogger(Neo4jHttpClient.class); public Neo4jConfiguration config; private HttpClient client; private Neo4jHttpClient(Neo4jConfiguration neo4jConfiguration) { this.config = neo4jConfiguration; try { this.start(); } catch (Exception e) { e.printStackTrace(); this.client = null; } } private static Map<Neo4jConfiguration, Neo4jHttpClient> INSTANCE_MAP = new ConcurrentHashMap<Neo4jConfiguration, Neo4jHttpClient>(); public static Neo4jHttpClient getInstance(Neo4jConfiguration neo4jConfiguration) { if (INSTANCE_MAP != null && INSTANCE_MAP.size() > 0 && INSTANCE_MAP.containsKey(neo4jConfiguration)) { return INSTANCE_MAP.get(neo4jConfiguration); } else { Neo4jHttpClient instance = new Neo4jHttpClient(neo4jConfiguration); if (instance != null && instance.client != null) { INSTANCE_MAP.put(neo4jConfiguration, instance); return instance; } else { return null; } } } public void start() throws Exception { Objects.nonNull(config); assertThat("config.getScheme().startsWith(\"http\")", config.getScheme().startsWith("http")); LOGGER.info("Neo4jConfiguration.start {}", config); Objects.nonNull(client); } public void stop() throws Exception { this.client = null; } public Neo4jConfiguration config() { return config; } public HttpClient client() { return client; } }