利用Netty中提供的HttpChunk简单实现文件传输。 服务端基本和Netty官方文档中的example：http--file一样。

HttpClient.java

public class HttpClient {

    private ClientBootstrap bootstrap;
    private String host="localhost";
    private Channel channel;
    private boolean futureSuccess;
    private int port=8080;

    public HttpClient() {
    }

    public ChannelFuture connect() {
        bootstrap = new ClientBootstrap(new NioClientSocketChannelFactory(Executors.newCachedThreadPool(), Executors
                .newCachedThreadPool()));
        HttpResponseHandler clientHandler = new HttpResponseHandler();
        bootstrap.setPipelineFactory(new HttpClientPipelineFactory(clientHandler));

        bootstrap.setOption("tcpNoDelay", true);
        bootstrap.setOption("keepAlive", true);

        return bootstrap.connect(new InetSocketAddress(host,port));
    }

    public boolean checkFutureState(ChannelFuture channelFuture) {
        // Wait until the connection attempt succeeds or fails.
        channel = channelFuture.awaitUninterruptibly().getChannel();
        channelFuture.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture connectFuture) throws Exception {
                if (!connectFuture.isSuccess()) {
                    connectFuture.getCause().printStackTrace();
                    // connectFuture.getChannel().close();
                    // bootstrap.releaseExternalResources();
                    futureSuccess = false;
                } else {
                    futureSuccess = true;
                }
            }
        });
        return futureSuccess;
    }

    public ChannelFuture write(HttpRequest request) {
        return channel.write(request);
    }

    public void Close() {
        // Close the connection. Make sure the close operation ends because
        // all I/O operations are asynchronous in Netty.
        channel.close().awaitUninterruptibly();
        // Shut down all thread pools to exit.
        bootstrap.releaseExternalResources();
    }
}

HttpClientPipelineFactory.java

public class HttpClientPipelineFactory implements ChannelPipelineFactory {  
    private final HttpResponseHandler handler;  

    public HttpClientPipelineFactory(HttpResponseHandler handler) {  
        this.handler = handler;  
    }  

    public ChannelPipeline getPipeline() throws Exception {  
        ChannelPipeline pipeline = pipeline();  

        pipeline.addLast("decoder", new HttpResponseDecoder());  
        //pipeline.addLast("aggregator", new HttpChunkAggregator(6048576));  
        pipeline.addLast("encoder", new HttpRequestEncoder());  
        pipeline.addLast("chunkedWriter", new ChunkedWriteHandler());  
        pipeline.addLast("handler", handler);  

        return pipeline;  
    }  
}  

HttpResponseHandler.java

@ChannelPipelineCoverage("one")  
public class HttpResponseHandler extends SimpleChannelUpstreamHandler {  
    private volatile boolean readingChunks;  
    private File downloadFile;  
    private FileOutputStream fOutputStream = null;  

    @Override  
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {  
        if (e.getMessage() instanceof HttpResponse) {  
            DefaultHttpResponse httpResponse = (DefaultHttpResponse) e.getMessage();  
            String fileName = httpResponse.getHeader("Content-Disposition").substring(20);  
            downloadFile = new File(System.getProperty("user.dir") + File.separator + "download" + fileName);  
            readingChunks = httpResponse.isChunked();  
        } else {  
            HttpChunk httpChunk = (HttpChunk) e.getMessage();  
            if (!httpChunk.isLast()) {  
                ChannelBuffer buffer = httpChunk.getContent();  
                if (fOutputStream == null) {  
                    fOutputStream = new FileOutputStream(downloadFile);  
                }  
                while (buffer.readable()) {  
                    byte[] dst = new byte[buffer.readableBytes()];  
                    buffer.readBytes(dst);  
                    fOutputStream.write(dst);  
                }  
            } else {  
                readingChunks = false;  
            }  
            fOutputStream.flush();  
        }  
        if (!readingChunks) {  
            fOutputStream.close();  
        }  
    }  

    @Override  
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {  
        System.out.println(e.getCause());  
    }  
}  

ClientMain.java

public class ClientMain {  
    public static void main(String[] args) {  
        HttpClient httpClient=new HttpClient();  
        ChannelFuture connectFuture=httpClient.connect();  
        if (httpClient.checkFutureState(connectFuture)) {  
            System.out.println("connect ok");  
            HttpRequest request=new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, "thunder.zip");  
//          HttpRequest request=new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, "thunder.java");  
            ChannelFuture writeFuture= httpClient.write(request);  
            if (httpClient.checkFutureState(writeFuture)) {  
                System.out.println("write ok");  
            }  
        }  
    }  
}