6、netty http协议开发应用(netty学习笔记)

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1、Netty http服务端入门

1.1http文件服务器。

package com.play.netty.http.fileserver;

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;

/**
* 简单的基于HTTP的文件服务器
* Created by IntelliJ IDEA.
* User: GongQi
* Date: 2017/9/25
*/
public class HttpFileServer {

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

    public void run(String host, Integer port, final String url) throws InterruptedException {

        //启动2个线程组
        final EventLoopGroup bossGrop = new NioEventLoopGroup();
        EventLoopGroup workGrop = new NioEventLoopGroup();

        try {
            //启动器
            ServerBootstrap bootstrap = new ServerBootstrap();
            //绑定线组
            bootstrap.group(bossGrop, workGrop)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline()
                                    .addLast("http-decoder", new HttpRequestDecoder());
                            //它的作用是将多个消息转换为单一的FullHttpRequest或者FullHttpResponse
                            //http解码器在每个http消息体中会生成多个消息对象
                            //(1)HttpRequest\HttpResponse
                            //(2)HttpContent
                            //(3)LastHttpContent
                            socketChannel.pipeline()
                                    .addLast("http-aggregator", new HttpObjectAggregator(65536));
                            socketChannel.pipeline()
                                    .addLast("http-encoder", new HttpResponseEncoder());
                            //为了支持异步发送大码流，不占用过多内存防止内存溢出
                            socketChannel.pipeline()
                                    .addLast("http-chunked", new ChunkedWriteHandler());
                            //我们需要的业务处理器
                            socketChannel.pipeline()
                                    .addLast("fileServerHander", new HttpFileServerHander(url));
                        }
                    });

            //绑定端口
            ChannelFuture channelFuture = bootstrap.bind(host, port).sync();
            System.out.println("系统启动完毕........");
            //同步等待
            channelFuture.channel().closeFuture().sync();

        } finally {
            bossGrop.shutdownGracefully();
            workGrop.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        Integer port = 8080;
        String url = DEFAULT_URL;
        new HttpFileServer().run("localhost", port, url);
    }
}

HttpFileServerHander.java

package com.play.netty.http.fileserver;

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.regex.Pattern;

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.HttpHeaders.isKeepAlive;
import static io.netty.handler.codec.http.HttpHeaders.setContentLength;
import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpResponseStatus.*;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

/**
* Created by IntelliJ IDEA.
* User: GongQi
* Date: 2017/9/25
*/
public class HttpFileServerHander extends SimpleChannelInboundHandler<FullHttpRequest> {

    private final String url;
    private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");
    private static final Pattern ALLOWED_FILE_NAME = Pattern
            .compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");

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

    public void messageReceived(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {

        //如果解码失败则返回错误
        if (!request.getDecoderResult().isSuccess()) {
            sendError(ctx, BAD_REQUEST);
            return;
        }

        //如果不是get则报错
        if (request.getMethod() != GET) {
            sendError(ctx, METHOD_NOT_ALLOWED);
            return;
        }

        //获取uri并加工
        final String uri = request.getUri();
        final String path = sanitizeUri(uri);

        if (path == null) {
            sendError(ctx, FORBIDDEN);
            return;
        }
        //
        //获取文件
        File file = new File(path);
        if (file.isHidden() || !file.exists()) {
            sendError(ctx, NOT_FOUND);
            return;
        }

        //如果是目录则返回目录信息
        if (file.isDirectory()) {
            if (uri.endsWith("/")) {
                sendListing(ctx, file);
            } else {
                sendRedirect(ctx, uri + "/");
            }
            return;
        }
        if(!file.isFile()){
            sendError(ctx,FORBIDDEN);
        }

        RandomAccessFile randomAccessFile;
        try {
            randomAccessFile = new RandomAccessFile(file, "r");
        } catch (FileNotFoundException e) {
            sendError(ctx, NOT_FOUND);
            return;
        }
        //获取文件的长度
        long fileLength = randomAccessFile.length();
        //构造HTTP应答消息，这边不能用FullHttpResponse，原因后续再说。
        HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
        setContentLength(response, fileLength);
        setContentTypeHeader(response, file);
        //判断是否keep-alive
        if (isKeepAlive(request)) {
            response.headers().set(CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
        }
        ctx.write(response);
        //通过Netty的ChunkedFile将文件直接写入到发送缓冲区
        ChannelFuture sendFileFeature;
        sendFileFeature= ctx.write(new ChunkedFile(randomAccessFile, 0,
                                fileLength, 8192), ctx.newProgressivePromise());
        //添加GenericProgressiveFutureListener,如果发送完成打印 System.out.println("Transfer complete");
        sendFileFeature.addListener(new ChannelProgressiveFutureListener() {
            //
            public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) throws Exception {
                if (total < 0) {
                    System.err.println("Transfer progress:" + progress);
                } else {
                    System.err.println("Transfer progress:" + progress + "/" + total);
                }
            }

            public void operationComplete(ChannelProgressiveFuture future) throws Exception {
                System.out.println("Transfer complete");
            }
        });
        //发送一个EMPTY_LAST_CONTENT说明完成
        ChannelFuture lastContentFuture = ctx
                .writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);

        if (!isKeepAlive(request)) {
            lastContentFuture.addListener(ChannelFutureListener.CLOSE);
        }
    }

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

    /**
    * 构造错误信息
    *
    * @param ch
    * @param status
    */
    private void sendError(ChannelHandlerContext ch, HttpResponseStatus status) {
        FullHttpResponse response = new DefaultFullHttpResponse(
                HTTP_1_1,
                status,
                Unpooled.copiedBuffer("Faile: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
        //
        response.headers().set(CONTENT_TYPE, "text/plain; charset=UTF-8");

        ch.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    /**
    * 加工url
    * @param uri
    * @return
    */
    private String sanitizeUri(String uri) {
        //先用UTF-8解码，如果失败了在用ISO-8859-1
        try {
            uri = URLDecoder.decode(uri, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            try {
                uri = URLDecoder.decode(uri, "ISO-8859-1");
            } catch (UnsupportedEncodingException e1) {
                throw new Error();
            }
        }
        //如果不是符合规范的请求，则拒绝
        if (!uri.startsWith(url) || !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;
    }

    /**
    * 构造显示的列表信息
    * @param context
    * @param dir
    */
    private void sendListing(ChannelHandlerContext context, File dir) {

        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK);
        //创建成功的http相应消息，使用text/html便于直接显示再浏览器上
        response.headers().set(CONTENT_TYPE, "text/html;charset=UTF-8");

        StringBuilder builder = new StringBuilder();
        String dirPath = dir.getPath();

        //拼接HTML
        builder.append("<!DOCTYPE html>\r\n");
        builder.append("<html><head><title>");
        builder.append(dirPath);
        builder.append("目录:");
        builder.append("</title></head><body>\r\n");
        builder.append("<h3>");
        builder.append(dirPath).append(" 目录: ");
        builder.append("</h3>\r\n");
        builder.append("<ul>");
        builder.append("<li>链接:<a href=\"../\">..</a></li>\r\n");
        //构造列表
        for (File file : dir.listFiles()) {
            if (file.isHidden() || !file.canRead()) {
                continue;
            }
            //过滤文件名
            String fileName = file.getName();
            if (!ALLOWED_FILE_NAME.matcher(fileName).matches()) {
                continue;
            }
            //超链接
            builder.append("<li>链接: <a href=\" ");
            builder.append(fileName);
            builder.append("\">");
            builder.append(fileName);
            builder.append("</a></li>\r\n");
        }
        builder.append("</ul></body></html>\r\n");

        //万能的ByteBuf
        ByteBuf byteBuf = Unpooled.copiedBuffer(builder, CharsetUtil.UTF_8);
        response.content().writeBytes(byteBuf);
        //释放缓存区
        byteBuf.release();
        context.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    /**
    * 从定向
    *
    * @param context
    * @param newUri
    */
    private void sendRedirect(ChannelHandlerContext context, String newUri) {

        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, FOUND);
        response.headers().set(LOCATION, newUri);
        context.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    public void exceptionCaught(ChannelHandlerContext context,Throwable cause){
        cause.printStackTrace();
        if(context.channel().isActive()){
            sendError(context,INTERNAL_SERVER_ERROR);
        }
    }
}