FileServerHandler Class — netty Architecture

Source Code

example/src/main/java/io/netty/example/file/FileServerHandler.java lines 28–72

public class FileServerHandler extends SimpleChannelInboundHandler<String> {

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        ctx.writeAndFlush("HELLO: Type the path of the file to retrieve.\n");
    }

    @Override
    public void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        RandomAccessFile raf = null;
        long length = -1;
        try {
            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();
            }
        }

        ctx.write("OK: " + raf.length() + '\n');
        if (ctx.pipeline().get(SslHandler.class) == null) {
            // SSL not enabled - can use zero-copy file transfer.
            ctx.write(new DefaultFileRegion(raf.getChannel(), 0, length));
        } else {
            // SSL enabled - cannot use zero-copy file transfer.
            ctx.write(new ChunkedFile(raf));
        }
        ctx.writeAndFlush("\n");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();

        if (ctx.channel().isActive()) {
            ctx.writeAndFlush("ERR: " +
                    cause.getClass().getSimpleName() + ": " +
                    cause.getMessage() + '\n').addListener(ChannelFutureListener.CLOSE);
        }
    }
}