| /**************************************************************** |
| * 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.james.mime4j.storage; |
| |
| /** |
| * Allows for a default {@link StorageProvider} instance to be configured on an |
| * application level. |
| * <p> |
| * The default instance can be set by either calling |
| * {@link #setInstance(StorageProvider)} when the application starts up or by |
| * setting the system property |
| * <code>org.apache.james.mime4j.defaultStorageProvider</code> to the class |
| * name of a <code>StorageProvider</code> implementation. |
| * <p> |
| * If neither option is used or if the class instantiation fails this class |
| * provides a pre-configured default instance. |
| */ |
| public class DefaultStorageProvider { |
| |
| /** Value is <code>org.apache.james.mime4j.defaultStorageProvider</code> */ |
| public static final String DEFAULT_STORAGE_PROVIDER_PROPERTY = |
| "org.apache.james.mime4j.defaultStorageProvider"; |
| |
| private static volatile StorageProvider instance = null; |
| |
| static { |
| initialize(); |
| } |
| |
| private DefaultStorageProvider() { |
| } |
| |
| /** |
| * Returns the default {@link StorageProvider} instance. |
| * |
| * @return the default {@link StorageProvider} instance. |
| */ |
| public static StorageProvider getInstance() { |
| return instance; |
| } |
| |
| /** |
| * Sets the default {@link StorageProvider} instance. |
| * |
| * @param instance |
| * the default {@link StorageProvider} instance. |
| */ |
| public static void setInstance(StorageProvider instance) { |
| if (instance == null) { |
| throw new IllegalArgumentException(); |
| } |
| |
| DefaultStorageProvider.instance = instance; |
| } |
| |
| private static void initialize() { |
| String clazz = System.getProperty(DEFAULT_STORAGE_PROVIDER_PROPERTY); |
| try { |
| if (clazz != null) { |
| instance = (StorageProvider) Class.forName(clazz).newInstance(); |
| } |
| } catch (Exception e) { |
| } |
| if (instance == null) { |
| StorageProvider backend = new TempFileStorageProvider(); |
| instance = new ThresholdStorageProvider(backend, 1024); |
| } |
| } |
| |
| // for unit tests only |
| static void reset() { |
| instance = null; |
| initialize(); |
| } |
| |
| } |