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GCS based Storage Provider for mime4j
import com.google.appengine.tools.cloudstorage.GcsFileOptions;
import com.google.appengine.tools.cloudstorage.GcsFilename;
import com.google.appengine.tools.cloudstorage.GcsInputChannel;
import com.google.appengine.tools.cloudstorage.GcsOutputChannel;
import com.google.appengine.tools.cloudstorage.GcsService;
import lombok.extern.slf4j.Slf4j;
import org.apache.james.mime4j.storage.AbstractStorageProvider;
import org.apache.james.mime4j.storage.Storage;
import org.apache.james.mime4j.storage.StorageOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.channels.Channels;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.UUID;
/**
* A {@link org.apache.james.mime4j.storage.StorageProvider} that stores the data in google cloud storage files. The files
* are stored in a user specified bucket. User of this class needs to supply the google cloud storage service and bucket name.
*
* This implementation is based on {@link org.apache.james.mime4j.storage.TempFileStorageProvider}
* <p>
* Example usage:
*
* <pre>
* final String bucketName = "my-bucket";
* DefaultStorageProvider.setInstance(new GcsStorageProvider(gcsService, bucketName));
* </pre>
*/
@Slf4j
public class GcsStorageProvider extends AbstractStorageProvider {
private static final int FETCH_SIZE_MB = 4 * 1024 * 1024;
private static final String PUBLIC_READ = "public-read";
private static final GcsFileOptions gcsFileOpts = new GcsFileOptions.Builder().acl(PUBLIC_READ).mimeType("text/csv").build();
private final GcsService gcsService;
private final String bucketName;
/**
* Creates a new <code>GcsStorageProvider</code> using the given
* values.
*
* @param gcsService an implementation of {@link GcsService}
* @param bucketName google cloud storage bucket name to use.
*/
public GcsStorageProvider(final GcsService gcsService, final String bucketName) {
this.gcsService = gcsService;
this.bucketName = bucketName;
}
@Override
public StorageOutputStream createStorageOutputStream() throws IOException {
return new GcsStorageProvider.GcsStorageOutputStream(gcsService, bucketName);
}
private static final class GcsStorage implements Storage {
private final GcsService gcsService;
private GcsFilename gcsFilename;
private static final Set<GcsFilename> filesToDelete = new HashSet();
public GcsStorage(final GcsService gcsService, final GcsFilename gcsFilename) {
this.gcsService = gcsService;
this.gcsFilename = gcsFilename;
}
@Override
public InputStream getInputStream() throws IOException {
if (this.gcsFilename == null) {
throw new IllegalStateException("storage has been deleted");
} else {
final GcsInputChannel readChannel = gcsService.openPrefetchingReadChannel(gcsFilename, 0, FETCH_SIZE_MB);
return Channels.newInputStream(readChannel);
}
}
@Override
public void delete() {
synchronized(filesToDelete) {
if (this.gcsFilename != null) {
filesToDelete.add(this.gcsFilename);
this.gcsFilename = null;
}
final Iterator iterator = filesToDelete.iterator();
while(iterator.hasNext()) {
GcsFilename filename = (GcsFilename)iterator.next();
try {
if (gcsService.delete(filename)) {
iterator.remove();
}
} catch (final IOException ex) {
log.error(ex.getMessage(), ex);
}
}
}
}
}
private static final class GcsStorageOutputStream extends StorageOutputStream {
private final GcsService gcsService;
private GcsFilename gcsFilename;
private final OutputStream outputStream;
public GcsStorageOutputStream(final GcsService gcsService, final String bucketName) throws IOException {
this.gcsService = gcsService;
final String fileName = UUID.randomUUID().toString();
this.gcsFilename = new GcsFilename(bucketName, fileName);
GcsOutputChannel gcsOutputChannel = gcsService.createOrReplace(gcsFilename, gcsFileOpts);
this.outputStream = Channels.newOutputStream(gcsOutputChannel);
}
@Override
protected void write0(byte[] buffer, int offset, int length) throws IOException {
this.outputStream.write(buffer, offset, length);
}
@Override
protected Storage toStorage0() throws IOException {
return new GcsStorage(gcsService, gcsFilename);
}
@Override
public void close() throws IOException {
super.close();
this.outputStream.close();
}
}
}
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