org.glassfish.grizzly.samples.httpserver.nonblockinghandler.DownloadHttpHandlerSample Maven / Gradle / Ivy
/*
* Copyright (c) 2011, 2020 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.glassfish.grizzly.samples.httpserver.nonblockinghandler;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.glassfish.grizzly.Buffer;
import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.WriteHandler;
import org.glassfish.grizzly.http.io.NIOOutputStream;
import org.glassfish.grizzly.http.server.HttpHandler;
import org.glassfish.grizzly.http.server.HttpServer;
import org.glassfish.grizzly.http.server.NetworkListener;
import org.glassfish.grizzly.http.server.Request;
import org.glassfish.grizzly.http.server.Response;
import org.glassfish.grizzly.http.server.ServerConfiguration;
import org.glassfish.grizzly.http.util.HttpStatus;
import org.glassfish.grizzly.http.util.MimeType;
import org.glassfish.grizzly.memory.MemoryManager;
/**
* The sample shows how the HttpHandler should be implemented in order to send large amount of data to a client in a
* non-blocking mode.
*
* This sample is not intended to show the most optimal way to transfer file data to a client. It supposed to
* demonstrate how to work with NIO output stream.
*
* @author Alexey Stashok
*/
public class DownloadHttpHandlerSample {
private static final Logger LOGGER = Grizzly.logger(DownloadHttpHandlerSample.class);
private static final int CHUNK_SIZE = 8192;
public static void main(String[] args) {
// Read command line parameter - the parent directory
if (args.length == 0) {
System.out.println("Usage: DownloadHttpHandlerSample ");
System.exit(1);
}
// Check the parent directory
final String downloadFolderName = args[0];
final File downloadFolder = new File(downloadFolderName);
if (!downloadFolder.isDirectory()) {
System.out.println("The argument " + downloadFolderName + " is not a folder!");
System.exit(1);
}
// create a basic server that listens on port 8080
final NetworkListener networkListener = new NetworkListener("downloader", "0.0.0.0", 8080);
// limit the max async write queue size per connection
// usually we have to make the size big enough to accept data chunk + HTTP headers.
networkListener.setMaxPendingBytes(CHUNK_SIZE * 4);
final HttpServer server = new HttpServer();
server.addListener(networkListener);
final ServerConfiguration config = server.getServerConfiguration();
// Map the NonBlockingUploadHandler to "/" URL
config.addHttpHandler(new NonBlockingDownloadHandler(downloadFolder), "/");
try {
server.start();
LOGGER.info("Press enter to stop the server...");
System.in.read();
} catch (IOException ioe) {
LOGGER.log(Level.SEVERE, ioe.toString(), ioe);
} finally {
server.shutdownNow();
}
}
/**
* This handler using non-blocking streams to write large amount of data to a client.
*/
private static class NonBlockingDownloadHandler extends HttpHandler {
private final File parentFolder;
public NonBlockingDownloadHandler(final File parentFolder) {
this.parentFolder = parentFolder;
}
// -------------------------------------------- Methods from HttpHandler
@Override
public void service(final Request request, final Response response) throws Exception {
// Disable internal Response buffering
response.setBufferSize(0);
// put the stream in non-blocking mode
final NIOOutputStream output = response.getNIOOutputStream();
// get file path
final String path = request.getDecodedRequestURI();
final File file = new File(parentFolder, path);
// check if file exists
if (!file.isFile()) {
response.setStatus(HttpStatus.NOT_FOUND_404);
return;
}
final FileChannel fileChannel = new FileInputStream(file).getChannel();
// set content-type
final String contentType = MimeType.getByFilename(path);
response.setContentType(contentType != null ? contentType : "binary/octet-stream");
response.suspend(); // !!! suspend the Request
// Notify the handler once we can write CHUNK_SIZE of data
output.notifyCanWrite(new WriteHandler() {
// keep the remaining size
private long size = file.length();
@Override
public void onWritePossible() throws Exception {
LOGGER.log(Level.FINE, "[onWritePossible]");
// send CHUNK of data
final boolean isWriteMore = sendChunk();
if (isWriteMore) {
// if there are more bytes to be sent - reregister this WriteHandler
output.notifyCanWrite(this);
}
}
@Override
public void onError(Throwable t) {
LOGGER.log(Level.WARNING, "[onError] ", t);
response.setStatus(500, t.getMessage());
complete(true);
}
/**
* Send next CHUNK_SIZE of file
*/
private boolean sendChunk() throws IOException {
// allocate Buffer
final MemoryManager mm = request.getContext().getMemoryManager();
final Buffer buffer = mm.allocate(CHUNK_SIZE);
// mark it available for disposal after content is written
buffer.allowBufferDispose(true);
// read file to the Buffer
final int justReadBytes = fileChannel.read(buffer.toByteBuffer());
if (justReadBytes <= 0) {
complete(false);
return false;
}
// prepare buffer to be written
buffer.position(justReadBytes);
buffer.trim();
// write the Buffer
output.write(buffer);
size -= justReadBytes;
// check the remaining size here to avoid extra onWritePossible() invocation
if (size <= 0) {
complete(false);
return false;
}
return true;
}
/**
* Complete the download
*/
private void complete(final boolean isError) {
try {
fileChannel.close();
} catch (IOException e) {
if (!isError) {
response.setStatus(500, e.getMessage());
}
}
try {
output.close();
} catch (IOException e) {
if (!isError) {
response.setStatus(500, e.getMessage());
}
}
if (response.isSuspended()) {
response.resume();
} else {
response.finish();
}
}
});
}
} // END NonBlockingDownloadHandler
}