【发布时间】：2018-11-28 19:20:04
【问题描述】：
我正在设计一个基于 Netty 的解决方案，通过 TCP 将文件从服务器传输到客户端。客户端指定文件的位置，然后服务器将文件发送给客户端。
目前，该解决方案适用于小文件（
如果要发送的文件大于 ~5MB，只发送部分数据，这会有所不同（每次发送的数据量都不相同）。此外，从日志中可以看出，服务器已经发送了完整的数据量（文件）。
问题是客户端没有收到服务器发送的完整数据。我下面的代码有什么问题？或有人能指出我正确的方向吗？
以下是我的客户端、服务器及其处理程序： （为了简洁我只列出了重要的方法）
客户：
public class FileClient {
private final static int PORT = 8992;
private final static String HOST = "127.0.0.1";
public class ClientChannelInitializer extends ChannelInitializer<SocketChannel> {
private SslContext sslContext = null;
private String srcFile = "";
private String destFile = "";
public ClientChannelInitializer(String srcFile, String destFile, SslContext sslCtx) {
this.sslContext = sslCtx;
this.srcFile = srcFile;
this.destFile = destFile;
}
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast(sslContext.newHandler(socketChannel.alloc(), HOST, PORT));
pipeline.addLast("clientHandler", new FileClientHandler(srcFile, destFile));
}
}
private void startUp(String srcFile, String destFile) throws Exception {
SslContext sslCtx = SslContextBuilder.forClient().trustManager(InsecureTrustManagerFactory.INSTANCE).build();
EventLoopGroup workerGroup = new NioEventLoopGroup();
Bootstrap clientBootstrap = new Bootstrap();
clientBootstrap.group(workerGroup);
clientBootstrap.channel(NioSocketChannel.class);
clientBootstrap.option(ChannelOption.TCP_NODELAY, true);
clientBootstrap.handler(new LoggingHandler(LogLevel.INFO));
clientBootstrap.handler(new ClientChannelInitializer(srcFile, destFile, sslCtx));
Channel channel = clientBootstrap.connect(new InetSocketAddress(HOST, PORT)).sync().channel();
channel.closeFuture().sync();
}
}
public static void main(String[] args) throws Exception {
String src = "/Users/home/src/test.mp4";
String dest = "/Users/home/dest/test.mp4";
new FileClient().startUp(src, dest);
}
}
客户端处理程序：
public class FileClientHandler extends SimpleChannelInboundHandler<ByteBuf> {
private final String sourceFileName;
private OutputStream outputStream;
private Path destFilePath;
private byte[] buffer = new byte[0];
public FileClientHandler(String SrcFileName, String destFileName) {
this.sourceFileName = SrcFileName;
this.destFilePath = Paths.get(destFileName);
System.out.println("DestFilePath-" + destFilePath);
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
ctx.writeAndFlush(ToByteBuff(this.sourceFileName));
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, ByteBuf byteBuff) throws Exception {
if (this.outputStream == null) {
Files.createDirectories(this.destFilePath.getParent());
if (Files.exists(this.destFilePath)) {
Files.delete(this.destFilePath);
}
this.outputStream = Files.newOutputStream(this.destFilePath, StandardOpenOption.CREATE,
StandardOpenOption.APPEND);
}
int size = byteBuff.readableBytes();
if (size > this.buffer.length) {
this.buffer = new byte[size];
}
byteBuff.readBytes(this.buffer, 0, size);
this.outputStream.write(this.buffer, 0, size);
}
文件服务器：
public class FileServer {
private final int PORT = 8992;
public void run() throws Exception {
SelfSignedCertificate ssc = new SelfSignedCertificate();
final SslContext sslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey()).build();
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG, 100)
.handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(sslCtx.newHandler(ch.alloc()));
pipeline.addLast(new ChunkedWriteHandler());
pipeline.addLast(new FilServerFileHandler());
}
});
ChannelFuture f = b.bind(PORT).sync();
f.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new FileServer().run();
}
}
文件服务器处理程序：
public class FilServerFileHandler extends SimpleChannelInboundHandler<ByteBuf> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, ByteBuf buff) throws Exception {
String filePathStr = byteBuf.toString(CharsetUtil.UTF_8);
File file = new File(filePathStr);
RandomAccessFile raf = null;
ChannelFuture sendFileFuture;
try {
raf = new RandomAccessFile(file, "r");
sendFileFuture = ctx.writeAndFlush(new ChunkedNioFile(raf.getChannel()),
ctx.newProgressivePromise());
sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
public void operationComplete(ChannelProgressiveFuture future) throws Exception {
System.err.println("Transfer complete.");
}
public void operationProgressed(ChannelProgressiveFuture future, long progress, long total)
throws Exception {
if (total < 0) { // total unknown
System.err.println("Transfer progress: " + progress);
} else {
System.err.println("Transfer progress: " + progress + " / " + total);
}
}
});
} catch (FileNotFoundException fnfe) {
} finally {
if (raf != null)
raf.close();
}
}
【问题讨论】：
-
为什么不使用这里的方法：stackoverflow.com/questions/25888260/… 给您的客户？
-
谢谢。我也检查过这篇文章。即使这样也行不通。从服务器发送的任何数量 (> 5MB) 的数据中，最多只能接收/保存 5MB 的数据。
-
尝试在您的客户端和服务器处理程序中添加一个 exceptionCaught 方法，并检查在传输过程中是否引发了异常。而且，您的服务器是否在任何类型的代理后面？像 nginx 或 haproxy
-
@kelgon 我确实有 exceptionCaught 方法，只是为了简洁起见，我在这里没有提到它。 1. 不，在传输过程中没有抛出异常。 2. 不，不涉及代理。谢谢。