com.bennavetta.appsite.file.ResourceService.java Source code

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Here is the source code for com.bennavetta.appsite.file.ResourceService.java

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/**
 * Copyright 2013 Ben Navetta <ben@bennavetta.com>
 *
 * 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 com.bennavetta.appsite.file;

import static com.google.common.base.Preconditions.checkNotNull;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;

import com.google.appengine.api.blobstore.BlobstoreInputStream;
import com.google.appengine.api.files.AppEngineFile;
import com.google.appengine.api.files.FileReadChannel;
import com.google.appengine.api.files.FileService;
import com.google.appengine.api.files.FileServiceFactory;
import com.google.appengine.api.files.FileWriteChannel;
import com.google.appengine.api.files.LockException;
import com.google.common.net.MediaType;
import com.netflix.config.DynamicIntProperty;
import com.netflix.config.DynamicPropertyFactory;

@Service
public class ResourceService {
    private Logger log = LoggerFactory.getLogger(getClass());

    private DynamicIntProperty bufferSize = DynamicPropertyFactory.getInstance().getIntProperty("buffer.size",
            1024 * 8);

    private FileService fs = FileServiceFactory.getFileService();

    public Resource create(String path, MediaType mime, ReadableByteChannel src) throws IOException {
        String normalized = PathUtils.normalize(path);
        log.debug("Creating resource {}", normalized);

        AppEngineFile file = fs.createNewBlobFile(mime.toString(), normalized);
        FileWriteChannel channel = fs.openWriteChannel(file, true);

        MessageDigest digest = null;
        try {
            digest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException("MD5 not available", e);
        }
        ByteBuffer buf = ByteBuffer.allocateDirect(bufferSize.get());
        while (src.read(buf) != -1 || buf.position() != 0) {
            buf.flip();
            int read = channel.write(buf);
            if (read != 0) {
                int origPos = buf.position();
                int origLimit = buf.limit();
                buf.position(origPos - read);
                buf.limit(origPos);
                digest.update(buf);
                buf.limit(origLimit);
                buf.position(origPos);
            }

            buf.compact();
        }

        channel.closeFinally();
        Resource resource = new Resource(normalized, fs.getBlobKey(file).getKeyString(), digest.digest(), mime);
        resource.save();
        return resource;
    }

    public void download(Resource resource, WritableByteChannel dest) throws IOException {
        AppEngineFile file = fs.getBlobFile(resource.blobKey());
        try (FileReadChannel channel = fs.openReadChannel(file, false);) {
            copy(channel, dest);
        }
    }

    public ReadableByteChannel read(Resource resource) throws FileNotFoundException, LockException, IOException {
        checkNotNull(resource);
        log.debug("Reading {}", resource);
        AppEngineFile file = checkNotNull(fs.getBlobFile(resource.blobKey()));
        return fs.openReadChannel(file, false);
    }

    public InputStream readStream(Resource resource) throws IOException {
        checkNotNull(resource);
        return new BlobstoreInputStream(checkNotNull(resource.blobKey()));
    }

    private void copy(ReadableByteChannel src, WritableByteChannel dest) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocateDirect(bufferSize.get());
        while (src.read(buffer) != -1 || buffer.position() != 0) {
            buffer.flip();
            dest.write(buffer);
            buffer.compact();
        }
    }
}