001/****************************************************************
002 * Licensed to the Apache Software Foundation (ASF) under one   *
003 * or more contributor license agreements.  See the NOTICE file *
004 * distributed with this work for additional information        *
005 * regarding copyright ownership.  The ASF licenses this file   *
006 * to you under the Apache License, Version 2.0 (the            *
007 * "License"); you may not use this file except in compliance   *
008 * with the License.  You may obtain a copy of the License at   *
009 *                                                              *
010 *   http://www.apache.org/licenses/LICENSE-2.0                 *
011 *                                                              *
012 * Unless required by applicable law or agreed to in writing,   *
013 * software distributed under the License is distributed on an  *
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
015 * KIND, either express or implied.  See the License for the    *
016 * specific language governing permissions and limitations      *
017 * under the License.                                           *
018 ****************************************************************/
019
020package org.apache.james.mime4j.storage;
021
022import java.io.ByteArrayInputStream;
023import java.io.IOException;
024import java.io.InputStream;
025
026import org.apache.james.mime4j.util.ByteArrayBuffer;
027
028/**
029 * A {@link StorageProvider} that stores the data entirely in memory.
030 * <p>
031 * Example usage:
032 *
033 * <pre>
034 * StorageProvider provider = new MemoryStorageProvider();
035 * DefaultStorageProvider.setInstance(provider);
036 * </pre>
037 */
038public class MemoryStorageProvider extends AbstractStorageProvider {
039
040    /**
041     * Creates a new <code>MemoryStorageProvider</code>.
042     */
043    public MemoryStorageProvider() {
044    }
045
046    public StorageOutputStream createStorageOutputStream() {
047        return new MemoryStorageOutputStream();
048    }
049
050    private static final class MemoryStorageOutputStream extends
051            StorageOutputStream {
052        ByteArrayBuffer bab = new ByteArrayBuffer(1024);
053
054        @Override
055        protected void write0(byte[] buffer, int offset, int length)
056                throws IOException {
057            bab.append(buffer, offset, length);
058        }
059
060        @Override
061        protected Storage toStorage0() throws IOException {
062            return new MemoryStorage(bab.buffer(), bab.length());
063        }
064    }
065
066    static final class MemoryStorage implements Storage {
067        private byte[] data;
068        private final int count;
069
070        public MemoryStorage(byte[] data, int count) {
071            this.data = data;
072            this.count = count;
073        }
074
075        public InputStream getInputStream() throws IOException {
076            if (data == null)
077                throw new IllegalStateException("storage has been deleted");
078
079            return new ByteArrayInputStream(data, 0, count);
080        }
081
082        public void delete() {
083            data = null;
084        }
085    }
086
087}