使用Netty实现文件传输的HTTP服务器和客户端

现在我们来用netty实现文件传输的HTTP服务器和客户端

pom依赖文件：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>jdk21Test001</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>21</maven.compiler.source>
        <maven.compiler.target>21</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.86.Final</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.30</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
        <dependency>
            <groupId>jakarta.activation</groupId>
            <artifactId>jakarta.activation-api</artifactId>
            <version>2.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.angus</groupId>
            <artifactId>angus-mail</artifactId>
            <version>1.0.0</version>
        </dependency>
    </dependencies>

</project>

1、现在开始搞服务端代码。

服务端代码：

package com.netty.file;

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/resources/";

    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
                        public 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).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;
        String url = DEFAULT_URL;
        new HttpFileServer().run(port, url);
    }
}

服务端处理器代码：

package com.netty.file;

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 jakarta.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;

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 {
        if (!request.decoderResult().isSuccess()) {
            sendError(ctx, HttpResponseStatus.BAD_REQUEST);
            return;
        }
        if (request.method() != HttpMethod.GET) {
            sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED);
            return;
        }
        final String uri = request.uri();
        final String path = sanitizeUri(uri);
        if (path == null) {
            sendError(ctx, HttpResponseStatus.FORBIDDEN);
            return;
        }
        File file = new File(path);
        if (file.isHidden() || !file.exists()) {
            sendError(ctx, HttpResponseStatus.NOT_FOUND);
            return;
        }
        if (file.isDirectory()) {
            if (uri.endsWith("/")) {
                sendListing(ctx, file);
            } else {
                sendRedirect(ctx, uri + '/');
            }
            return;
        }
        if (!file.isFile()) {
            sendError(ctx, HttpResponseStatus.FORBIDDEN);
            return;
        }
        RandomAccessFile randomAccessFile = null;
        try {
            randomAccessFile = new RandomAccessFile(file, "r");
        } catch (FileNotFoundException e) {
            sendError(ctx, HttpResponseStatus.NOT_FOUND);
            return;
        }
        long fileLength = randomAccessFile.length();
        HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        HttpUtil.setContentLength(response, fileLength);
        setContentTypeHeader(response, file);
        if (HttpUtil.isKeepAlive(request)) {
            response.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
        }
        ctx.write(response);
        ChannelFuture sendFileFuture;
        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) {
                    System.err.println("Transfer progress: " + progress);
                } else {
                    System.err.println("Transfer progress: " + progress + " / " + total);
                }
            }

            @Override
            public void operationComplete(ChannelProgressiveFuture future) {
                System.err.println("Transfer complete.");
            }
        });
        ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
        if (!HttpUtil.isKeepAlive(request)) {
            lastContentFuture.addListener(ChannelFutureListener.CLOSE);
        }
    }

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

    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(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        response.headers().set(HttpHeaderNames.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(HttpVersion.HTTP_1_1, HttpResponseStatus.FOUND);
        response.headers().set(HttpHeaderNames.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(HttpHeaderNames.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(HttpHeaderNames.CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));
    }

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

在resource下面建立一个资源文件：index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>hello</title>
</head>
<body>
  <h1>Hello World</h1>
</body>
</html>

这个时候，我们用浏览器就可以直接访问了。

运行项目：

点击这个地址 http://127.0.0.1:8080/src/main/resources/ 这个地址。

点击index.html  可以直接显示出来。

2、现在我们开始搞客户端。

客户端代码：

package com.netty.file;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpRequestEncoder;
import io.netty.handler.codec.http.HttpResponseDecoder;

public class HttpFileClient {

    public void connect(String host, int port, final String fileName) throws Exception {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast("http-decoder", new HttpResponseDecoder());
                            ch.pipeline().addLast("http-aggregator", new HttpObjectAggregator(65536));
                            ch.pipeline().addLast("http-encoder", new HttpRequestEncoder());
                            ch.pipeline().addLast("fileClientHandler", new HttpFileClientHandler(fileName));
                        }
                    });

            ChannelFuture future = b.connect(host, port).sync();
            future.channel().closeFuture().sync();
        } finally {
            group.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        String host = "127.0.0.1";
        int port = 8080;
        String fileName = "/src/main/resources/index.html";
        new HttpFileClient().connect(host, port, fileName);
    }
}

客户端处理器：

package com.netty.file;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.*;
import io.netty.util.CharsetUtil;

public class HttpFileClientHandler extends SimpleChannelInboundHandler<HttpObject> {

    private final String fileName;

    public HttpFileClientHandler(String fileName) {
        this.fileName = fileName;
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        HttpRequest request = new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, fileName);
        request.headers().set(HttpHeaderNames.HOST, "127.0.0.1");
        request.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.CLOSE);
        request.headers().set(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.GZIP.toString() + ',' + HttpHeaderValues.DEFLATE.toString());
        ctx.writeAndFlush(request);
    }

    @Override
    public void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
        if (msg instanceof HttpResponse) {
            HttpResponse response = (HttpResponse) msg;
            System.out.println("STATUS: " + response.status());
            System.out.println("VERSION: " + response.protocolVersion());
            System.out.println();
            if (!response.status().equals(HttpResponseStatus.OK)) {
                ctx.close();
                return;
            }
        }
        if (msg instanceof HttpContent) {
            HttpContent content = (HttpContent) msg;
            ByteBuf buf = content.content();
            System.out.print(buf.toString(CharsetUtil.UTF_8));
            buf.release();
            if (msg instanceof LastHttpContent) {
                ctx.close();
            }
        }
    }

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

在服务端启动的条件下，启动客户端。结果展示：

这里只是将它们输出到控制台而已，如果想要实现下载，只需要在输出的时候调用：

 FileChannel fileChannel = new RandomAccessFile(new File("index.html"), "rw").getChannel();
            buf.readBytes(fileChannel, buf.readableBytes());

这样就行了。

结果展示:

下载成功。

var code = "31f212ba-75f6-4571-85e0-e91b3e1bf086"