Netty基于Http协议的服务端入门开发

package com.dpb.netty.http;

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 {

	private static final String DEFAULT_URL = "/src/main/java/com/dpb/netty/";

	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 {
							// 添加请求消息解码器
							ch.pipeline().addLast("http-decoder", new HttpRequestDecoder());
							//HttpObjectAggregator的作用 将多个消息转换为单一的FullHttpRequest或者FullHttpResponse
							ch.pipeline().addLast("http-aggregator", new HttpObjectAggregator(65536));
							// 添加响应解码器
							ch.pipeline().addLast("http-encoder", new HttpResponseEncoder());
							// 支持异步发送大的码流(大的文件传输),但不占用过多的内存，防止java内存溢出
							ch.pipeline().addLast("http-chunked", new ChunkedWriteHandler());
							// 添加自定义handler 处理文件服务器业务逻辑
							ch.pipeline().addLast("fileServerHandler", new HttpFileServerHandler(url));
						}
					});
			ChannelFuture future = b.bind("127.0.0.1", port).sync();
			System.out.println("HTTP文件目录服务器启动，网址是 : " + "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.length > 0) {
			try {
				port = Integer.parseInt(args[0]);
			} catch (NumberFormatException e) {
				e.printStackTrace();
			}
		}
		String url = DEFAULT_URL;
		if (args.length > 1)
			url = args[1];
		new HttpFileServer().run(port, url);
	}
}

package com.dpb.netty.http;

import static io.netty.handler.codec.http.HttpHeaders.isKeepAlive;
import static io.netty.handler.codec.http.HttpHeaders.setContentLength;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONNECTION;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_TYPE;
import static io.netty.handler.codec.http.HttpHeaders.Names.LOCATION;
import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN;
import static io.netty.handler.codec.http.HttpResponseStatus.FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
import static io.netty.handler.codec.http.HttpResponseStatus.METHOD_NOT_ALLOWED;
import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.OK;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.regex.Pattern;

import javax.activation.MimetypesFileTypeMap;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelProgressiveFuture;
import io.netty.channel.ChannelProgressiveFutureListener;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.LastHttpContent;
import io.netty.handler.stream.ChunkedFile;
import io.netty.util.CharsetUtil;

public class HttpFileServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

	private final String url;

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

	@Override
	public void messageReceived(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
		// 解码失败 400
		if (!request.getDecoderResult().isSuccess()) {
			sendError(ctx, BAD_REQUEST);
			return;
		}
		// 只支持get方法
		if (request.getMethod() != GET) {
			sendError(ctx, METHOD_NOT_ALLOWED);
			return;
		}
		// 
		final String uri = request.getUri();
		// 处理Uri地址
		final String path = sanitizeUri(uri);
		
		if (path == null) {
			sendError(ctx, FORBIDDEN);
			return;
		}
		File file = new File(path);
		// 如果文件不存在，或不可访问
		if (file.isHidden() || !file.exists()) {
			sendError(ctx, NOT_FOUND);
			return;
		}
		// 如果请求是文件夹
		if (file.isDirectory()) {
			// 请求以 '/'结尾，列出该文件夹下的所有内容
			if (uri.endsWith("/")) {
				sendListing(ctx, file);
			} else {
				// 否则自动补全'/' 然后再重定向访问
				sendRedirect(ctx, uri + '/');
			}
			return;
		}
		
		if (!file.isFile()) {
			sendError(ctx, FORBIDDEN);
			return;
		}
		RandomAccessFile randomAccessFile = null;
		try {
			randomAccessFile = new RandomAccessFile(file, "r");// 以只读的方式打开文件
		} catch (FileNotFoundException fnfe) {
			sendError(ctx, NOT_FOUND);
			return;
		}
		long fileLength = randomAccessFile.length();
		// 创建一个默认的Http响应
		HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
		// 设置响应文件大小
		setContentLength(response, fileLength);
		// 设置 content Type
		setContentTypeHeader(response, file);
		// 设置 keep alive
		if (isKeepAlive(request)) {
			response.headers().set(CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
		}
		ctx.write(response);
		ChannelFuture sendFileFuture;
		//通过Netty的ChunkedFile对象直接将文件写入发送到缓冲区中
		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.");
			}
		});
		ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
		//如果不支持keep-Alive，服务器端主动关闭请求
		if (!isKeepAlive(request)) {
			lastContentFuture.addListener(ChannelFutureListener.CLOSE);
		}
	}

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

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

	/**
	 * 格式化uri并且获取路径
	 * @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(url)) {
			return null;
		}
		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(HTTP_1_1, OK);
		response.headers().set(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(" 目录：");
		buf.append("</title></head><body>\r\n");
		buf.append("<h3>");
		buf.append(dirPath).append(" 目录：");
		buf.append("</h3>\r\n");
		buf.append("<ul>");
		buf.append("<li>链接：<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>链接：<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(HTTP_1_1, FOUND);
		response.headers().set(LOCATION, newUri);
		ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
	}

	private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
		FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, status,
				Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
		response.headers().set(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(CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));
	}
}