基于Netty的HTTP檔案服務器

一個基于Netty的檔案服務器，

【使用jar包為： netty-all-4.0.42.Final.jar】

• 啟動類

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpRequestDecoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
import io.netty.handler.stream.ChunkedWriteHandler;

public class HttpFileServer {

    public static final String DEFAULT_URL = "/src/";

    public void run (final int port, final String url) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {

                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast("http-decoder", new HttpRequestDecoder());
                            ch.pipeline().addLast("http-aggregator", new HttpObjectAggregator(65536));
                            ch.pipeline().addLast("http-encoder", new HttpResponseEncoder());
                            ch.pipeline().addLast("http-chunked", new ChunkedWriteHandler());
                            ch.pipeline().addLast("fileServerHandler", new HttpFileServerHandler(url));

                        }
                    });
            ChannelFuture future = b.bind("127.0.0.1", port);
            System.out.println("HTTP 檔案服務器已經啟動， 網址為 http://127.0.0.1:" + port + url);

            future.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception{
        int port = 8080;
        if(args != null && args.length > 0) {
            try {
                port = Integer.valueOf(args[0]);
            } catch (NumberFormatException e) {
                e.printStackTrace();
            }
        }
        String url = DEFAULT_URL;
        if (args.length > 1)
            url = args[1];

        new HttpFileServer().run(port, url);

    }
}

• 處理類

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.handler.codec.http.*;
import io.netty.handler.stream.ChunkedFile;
import io.netty.util.CharsetUtil;

import javax.activation.MimetypesFileTypeMap;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Date;
import java.util.regex.Pattern;

public class HttpFileServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

    private final String url;

    public HttpFileServerHandler(String url){
        this.url=url;
    }


    @Override
    public void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
        Date date1 = new Date();
        System.out.println(date1);
        // 解碼失敗 400
        if (!request.getDecoderResult().isSuccess()) {
            sendError(ctx, HttpResponseStatus.BAD_REQUEST);
            return;
        }
        // 只支持get方法
        if (request.getMethod() != HttpMethod.GET) {
            sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED);
            return;
        }
        //
        final String uri = request.getUri();
        // 處理Uri地址
        final String path = sanitizeUri(uri);

        if (path == null) {
            sendError(ctx, HttpResponseStatus.FORBIDDEN);
            return;
        }
        File file = new File(path);
        // 如果檔案不存在，或不可訪問
        if (file.isHidden() || !file.exists()) {
            sendError(ctx, HttpResponseStatus.NOT_FOUND);
            return;
        }
        // 如果請求是檔案夾
        if (file.isDirectory()) {
            // 請求以 '/'結尾，列出該檔案夾下的所有內容
            if (uri.endsWith("/")) {
                sendListing(ctx, file);
            } else {
                // 否則自動補全'/' 然后再重定向訪問
                sendRedirect(ctx, uri + '/');
            }
            return;
        }

        if (!file.isFile()) {
            sendError(ctx, HttpResponseStatus.FORBIDDEN);
            return;
        }
        RandomAccessFile randomAccessFile = null;
        try {
            randomAccessFile = new RandomAccessFile(file, "r");// 以只讀的方式打開檔案
        } catch (FileNotFoundException fnfe) {
            sendError(ctx, HttpResponseStatus.NOT_FOUND);
            return;
        }
        long fileLength = randomAccessFile.length();
        // 創建一個默認的Http回應
        HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        // 設定回應檔案大小
        HttpHeaders.setContentLength(response, fileLength);
        // 設定 content Type
        setContentTypeHeader(response, file);
        // 設定 keep alive
        if (HttpHeaders.isKeepAlive(request)) {
            response.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
        }
        ctx.write(response);

        //通過Netty的ChunkedFile物件直接將檔案寫入發送到緩沖區中
        ChannelFuture sendFileFuture = ctx.write(new ChunkedFile(randomAccessFile, 0, fileLength, 8192), ctx.newProgressivePromise());
        sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
            @Override
            public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) {
                if (total < 0) { // total unknown
                    System.err.println("Transfer progress: " + progress);
                } else {
                    System.err.println("Transfer progress: " + progress + " / " + total);
                }
            }

            @Override
            public void operationComplete(ChannelProgressiveFuture future) throws Exception {
                System.out.println("Transfer complete. 共計用時： " + (new Date().getTime() - date1.getTime()));
            }
        });
        ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
        //如果不支持keep-Alive，服務器端主動關閉請求
        if (!HttpHeaders.isKeepAlive(request)) {
            lastContentFuture.addListener(ChannelFutureListener.CLOSE);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        if (ctx.channel().isActive()) {
            sendError(ctx, HttpResponseStatus.INTERNAL_SERVER_ERROR);
        }
    }

    private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");

    /**
     * 格式化uri并且獲取路徑
     *
     * @param uri
     * @return
     */
    private String sanitizeUri(String uri) {
        try {
            uri = URLDecoder.decode(uri, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            try {
                uri = URLDecoder.decode(uri, "ISO-8859-1");
            } catch (UnsupportedEncodingException e1) {
                throw new Error();
            }
        }
        if (!uri.startsWith("/")) {
            return null;
        }
        uri = uri.replace('/', File.separatorChar);
        if (uri.contains(File.separator + '.') || uri.contains('.' + File.separator) || uri.startsWith(".")
                || uri.endsWith(".") || INSECURE_URI.matcher(uri).matches()) {
            return null;
        }
        return System.getProperty("user.dir") + File.separator + uri;
    }

    private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");

    private static void sendListing(ChannelHandlerContext ctx, File dir) {
        FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "text/html; charset=UTF-8");
        StringBuilder buf = new StringBuilder();
        String dirPath = dir.getPath();
        buf.append("<!DOCTYPE html>\r\n");
        buf.append("<html><head><title>");
        buf.append(dirPath);
        buf.append(" 目錄：");
        buf.append("</title></head><body>\r\n");
        buf.append("<h3>");
        buf.append(dirPath).append(" 目錄：");
        buf.append("</h3>\r\n");
        buf.append("<ul>");
        buf.append("<li>鏈接：<a href=\"../\">..</a></li>\r\n");
        for (File f : dir.listFiles()) {
            if (f.isHidden() || !f.canRead()) {
                continue;
            }
            String name = f.getName();
            if (!ALLOWED_FILE_NAME.matcher(name).matches()) {
                continue;
            }
            buf.append("<li>鏈接：<a href=\"");
            buf.append(name);
            buf.append("\">");
            buf.append(name);
            buf.append("</a></li>\r\n");
        }
        buf.append("</ul></body></html>\r\n");
        ByteBuf buffer = Unpooled.copiedBuffer(buf, CharsetUtil.UTF_8);
        response.content().writeBytes(buffer);
        buffer.release();
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    private static void sendRedirect(ChannelHandlerContext ctx, String newUri) {
        FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.FOUND);
        response.headers().set(HttpHeaders.Names.LOCATION, newUri);
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
        FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, status,
                Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
        response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "text/plain; charset=UTF-8");
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    private static void setContentTypeHeader(HttpResponse response, File file) {
        MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();
        response.headers().set(HttpHeaders.Names.CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));
    }

}

然后 瀏覽器輸入：http://127.0.0.1:8080/src/ 可以測驗

• — 注： 參考書籍： Netty權威指南（第2版）