Netty: TCP客户端服务器文件传输:TooLongFrameException异常：
Netty: TCP客户端服务器文件传输:TooLongFrameException异常：
提问于 2018-11-05 00:59:44
我是netty的新手，我正在尝试设计一个解决方案，如下所示，用于通过TCP从服务器向客户端传输文件：
1. Zero copy based file transfer in case of non-ssl based transfer (Using default region of the file)
2. ChunkedFile transfer in case of SSL based transfer.客户端-服务器文件传输以这种方式工作：
1. The client sends the location of the file to be transfered
2. Based on the location (sent by the client) the server transfers the file to the client文件内容可以是任何内容(字符串、/image、/pdf等)和任何大小。
现在，我在服务器端得到这个TooLongFrameException:，尽管服务器只是解码从客户端接收到的路径，以便运行下面提到的代码(服务器/客户机)。
io.netty.handler.codec.TooLongFrameException: Adjusted frame length exceeds 65536: 215542494061 - discarded
at io.netty.handler.codec.LengthFieldBasedFrameDecoder.fail(LengthFieldBasedFrameDecoder.java:522)
at io.netty.handler.codec.LengthFieldBasedFrameDecoder.failIfNecessary(LengthFieldBasedFrameDecoder.java:500)现在，我的问题是：
- 编码器和解码器的顺序是否错了，及其配置？如果是，那么配置它以从服务器接收文件的正确方法是什么？
- 我浏览了几个相关的StackOverflow帖子-- 所以Q1，所以Q2，所以Q3，所以Q4。我了解了LengthFieldBasedDecoder，但不知道如何在服务器(编码端)配置相应的LengthFieldPrepender。根本不需要吗？
请给我指出正确的方向。
FileClient：
public final class FileClient {
static final boolean SSL = System.getProperty("ssl") != null;
static final int PORT = Integer.parseInt(System.getProperty("port", SSL ? "8992" : "8023"));
static final String HOST = System.getProperty("host", "127.0.0.1");
public static void main(String[] args) throws Exception {
// Configure SSL.
final SslContext sslCtx;
if (SSL) {
SelfSignedCertificate ssc = new SelfSignedCertificate();
sslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey()).build();
} else {
sslCtx = null;
}
// Configure the client
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.option(ChannelOption.SO_KEEPALIVE, true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
if (sslCtx != null) {
pipeline.addLast(sslCtx.newHandler(ch.alloc(), HOST, PORT));
}
pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(64*1024, 0, 8));
pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
pipeline.addLast(new ObjectDecoder(ClassResolvers.cacheDisabled(null)));
pipeline.addLast(new ObjectEncoder());
pipeline.addLast( new FileClientHandler()); }
});
// Start the server.
ChannelFuture f = b.connect(HOST,PORT).sync();
// Wait until the server socket is closed.
f.channel().closeFuture().sync();
} finally {
// Shut down all event loops to terminate all threads.
group.shutdownGracefully();
}
}
}FileClientHandler：
public class FileClientHandler extends ChannelInboundHandlerAdapter{
@Override
public void channelActive(ChannelHandlerContext ctx) {
String filePath = "/Users/Home/Documents/Data.pdf";
ctx.writeAndFlush(Unpooled.wrappedBuffer(filePath.getBytes()));
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("File Client Handler Read method...");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
}
}FileServer：
/**
* Server that accept the path of a file and echo back its content.
*/
public final class FileServer {
static final boolean SSL = System.getProperty("ssl") != null;
static final int PORT = Integer.parseInt(System.getProperty("port", SSL ? "8992" : "8023"));
public static void main(String[] args) throws Exception {
// Configure SSL.
final SslContext sslCtx;
if (SSL) {
SelfSignedCertificate ssc = new SelfSignedCertificate();
sslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey()).build();
} else {
sslCtx = null;
}
// Configure the server.
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_KEEPALIVE, true).handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
if (sslCtx != null) {
pipeline.addLast(sslCtx.newHandler(ch.alloc()));
}
pipeline.addLast("frameDecoder",new LengthFieldBasedFrameDecoder(64*1024, 0, 8));
pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
pipeline.addLast(new ObjectDecoder(ClassResolvers.cacheDisabled(null)));
pipeline.addLast(new ObjectEncoder());
pipeline.addLast(new ChunkedWriteHandler());
pipeline.addLast(new FileServerHandler());
}
});
// Start the server.
ChannelFuture f = b.bind(PORT).sync();
// Wait until the server socket is closed.
f.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}FileServerHandler：
public class FileServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object obj) throws Exception {
RandomAccessFile raf = null;
long length = -1;
try {
ByteBuf buff = (ByteBuf)obj;
byte[] bytes = new byte[buff.readableBytes()];
buff.readBytes(bytes);
String msg = new String(bytes);
raf = new RandomAccessFile(msg, "r");
length = raf.length();
} catch (Exception e) {
ctx.writeAndFlush("ERR: " + e.getClass().getSimpleName() + ": " + e.getMessage() + '\n');
return;
} finally {
if (length < 0 && raf != null) {
raf.close();
}
}
if (ctx.pipeline().get(SslHandler.class) == null) {
// SSL not enabled - can use zero-copy file transfer.
ctx.writeAndFlush(new DefaultFileRegion(raf.getChannel(), 0, length));
} else {
// SSL enabled - cannot use zero-copy file transfer.
ctx.writeAndFlush(new ChunkedFile(raf));
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
System.out.println("Exception server.....");
}
}回答 1
Stack Overflow用户
回答已采纳
发布于 2018-11-06 13:00:15
您的服务器/客户端有多处问题。首先，对于客户端，您不需要为服务器初始化SslContext，而是执行如下操作：
sslCtx = SslContextBuilder.forClient().trustManager(InsecureTrustManagerFactory.INSTANCE).build();在服务器端，您使用的SelfSignedCertificate本身并不是错误的，但希望提醒您，它只应用于调试目的，而不应用于生产。此外，您还使用了不建议使用的ChannelOption.SO_KEEPALIVE，因为保持活动间隔依赖于操作系统。此外，您还将Object En-/Decoder添加到管道中，在您的情况下，它不会做任何有用的事情，因此您可以删除它们。
此外，由于不完整和错误的参数列表，您配置了错误的LengthFieldBasedFrameDecoder。在netty博士中，您需要构造函数的版本，它定义了lengthFieldLength和initialBytesToStrip。除了不剥离长度字段之外，您还定义了错误的lengthFieldLength，应该与您的LengthFieldPrepender的lengthFieldLength相同，后者是4个字节。
new LengthFieldBasedFrameDecoder(64 * 1024, 0, 4, 0, 4)在这两个处理程序中，您没有在en-/解码您的Charset时指定一个String，这可能会导致问题，因为如果没有定义字符集，那么系统默认将被使用，这可能会有所不同。你可以这样做：
//to encode the String
string.getBytes(StandardCharsets.UTF_8);
//to decode the String
new String(bytes, StandardCharsets.UTF_8);此外，如果没有将DefaultFileRegion添加到管道中，则尝试使用SslHandler，如果不添加LengthFieldHandler，这会很好，因为它们需要byte[]的内存副本才能发送到添加的length字段。此外，我建议使用ChunkedNioFile而不是ChunkedFile，因为它是非阻塞的，这总是一件好事。你会这样做的：
new ChunkedNioFile(randomAccessFile.getChannel())关于如何解码ChunkedFile的最后一件事，因为它是分块的，您可以简单地用一个简单的OutputStream访问它们。下面是我的一个旧文件处理程序：
public class FileTransferHandler extends SimpleChannelInboundHandler<ByteBuf> {
private final Path path;
private final int size;
private final int hash;
private OutputStream outputStream;
private int writtenBytes = 0;
private byte[] buffer = new byte[0];
protected FileTransferHandler(Path path, int size, int hash) {
this.path = path;
this.size = size;
this.hash = hash;
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, ByteBuf byteBuf) throws Exception {
if(this.outputStream == null) {
Files.createDirectories(this.path.getParent());
if(Files.exists(this.path))
Files.delete(this.path);
this.outputStream = Files.newOutputStream(this.path, StandardOpenOption.CREATE, StandardOpenOption.APPEND);
}
int size = byteBuf.readableBytes();
if(size > this.buffer.length)
this.buffer = new byte[size];
byteBuf.readBytes(this.buffer, 0, size);
this.outputStream.write(this.buffer, 0, size);
this.writtenBytes += size;
if(this.writtenBytes == this.size && MurMur3.hash(this.path) != this.hash) {
System.err.println("Received file has wrong hash");
return;
}
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
if(this.outputStream != null)
this.outputStream.close();
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/53147024
复制相关文章
相似问题
腾讯云开发者
