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 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 org.apache.felix.useradmin.mongodb; import java.net.UnknownHostException; import java.util.ArrayList; import java.util.List; import java.util.concurrent.atomic.AtomicReference; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.Mongo; import com.mongodb.MongoException; import com.mongodb.ServerAddress; /** * Provides a simple facade for accessing MongoDB. */ final class MongoDB { private final List<ServerAddress> m_servers; private final String m_dbName; private final String m_collectionName; private final AtomicReference<Mongo> m_mongoRef; /** * Creates a new {@link MongoDB} instance. * * @param serverNames the space separated list of Mongo servers, cannot be <code>null</code> or empty; * @param dbName the name of the MongoDB to connect to, cannot be <code>null</code> or empty; * @param collectionName the name of the collection to use, cannot be <code>null</code> or empty. */ public MongoDB(String serverNames, String dbName, String collectionName) { if (serverNames == null || "".equals(serverNames.trim())) { throw new IllegalArgumentException("ServerNames cannot be null or empty!"); } if (dbName == null || "".equals(dbName.trim())) { throw new IllegalArgumentException("DbName cannot be null or empty!"); } if (collectionName == null || "".equals(collectionName.trim())) { throw new IllegalArgumentException("CollectionName cannot be null or empty!"); } m_mongoRef = new AtomicReference<Mongo>(); m_servers = parseServers(serverNames); m_dbName = dbName; m_collectionName = collectionName; } /** * Parses the space separated list of server names. * * @param serverNames the server names, cannot be <code>null</code>. * @return a list of {@link ServerAddress}es to connect to, never <code>null</code>. * @throws IllegalArgumentException in case the given server names was invalid. */ private static List<ServerAddress> parseServers(String serverNames) { String[] parts = serverNames.split("\\s+"); List<ServerAddress> servers = new ArrayList<ServerAddress>(); for (int i = 0; i < parts.length; i++) { String part = parts[i]; try { int colonPos = part.indexOf(":"); if (colonPos > 0 && (colonPos < part.length() - 1)) { String name = part.substring(0, colonPos); String portStr = part.substring(colonPos + 1); servers.add(new ServerAddress(name, Integer.valueOf(portStr))); } } catch (NumberFormatException e) { throw new IllegalArgumentException("Illegal port number in: " + part); } catch (UnknownHostException e) { throw new IllegalArgumentException("Unknown host: " + part); } } if (servers.isEmpty()) { throw new IllegalArgumentException("No (valid) servers defined!"); } return servers; } /** * Connects to the MongoDB with the supplied credentials. * * @param userName the optional user name to use; * @param password the optional password to use. * @return <code>true</code> if the connection was succesful, <code>false</code> otherwise. */ public boolean connect(String userName, String password) { Mongo newMongo = new Mongo(m_servers); Mongo oldMongo; do { oldMongo = m_mongoRef.get(); } while (!m_mongoRef.compareAndSet(oldMongo, newMongo)); DB db = newMongo.getDB(m_dbName); if ((userName != null) && (password != null)) { if (!db.authenticate(userName, password.toCharArray())) { return false; } } return true; } /** * Returns the database collection to work in. * * @return the {@link DBCollection}, never <code>null</code>. * @throws MongoException in case no connection to Mongo exists. */ public DBCollection getCollection() { Mongo mongo = m_mongoRef.get(); if (mongo == null) { throw new MongoException("Not connected to MongoDB!"); } DB db = mongo.getDB(m_dbName); return db.getCollection(m_collectionName); } /** * Disconnects from the MongoDB. */ public void disconnect() { Mongo mongo = m_mongoRef.get(); if (mongo != null) { try { mongo.close(); } finally { m_mongoRef.compareAndSet(mongo, null); } } } }