Netty简单的HTTP服务器

本文转载自：https://www.cnblogs.com/luangeng/p/7875710.html

HTTP协议：略

基于Netty的HTTP协议栈可以方便的进行异步非阻塞的HTTP服务器的开发。

当在浏览器中输入一个指向特定网页的URL时，浏览器就会生成一个HTTP请求，浏览器会与服务器建立TCP连接，当TCP可靠连接建立之后，浏览器会将生成的HTTP请求发送到服务器端。这时服务器程序接收到了信息将要去识别这个信息的内容，然后调用相应的服务程序，经过服务程序的分析和处理之后服务器端返回内容给浏览器。当服务器返回了内容给浏览器后，这时浏览器与服务器之间的数据交换完毕，这时TCP可靠连接就会断开。

下面是一个简单的例子，只处理GET请求：

html，css，js，jpg等资源位置如下

HttpServer

package com.luangeng.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;

/**

 * Created by LG on 2017/11/21.

 */

public class HttpServer {

    public void run(final int port) 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 {

                            // HTTP请求消息解码器

                            ch.pipeline().addLast("http-decoder", new HttpRequestDecoder());

                            /*

                             * HttpObjectAggregator解码器

                             * 将多个消息转换为单一的FullHttpRequest或FullHttpResponse对象

                             */

                            ch.pipeline().addLast("http-aggregator", new HttpObjectAggregator(65536));

                            //HTTP响应编码器,对HTTP响应进行编码

                            ch.pipeline().addLast("http-encoder", new HttpResponseEncoder());

                            //ChunkedWriteHandler的主要作用是支持异步发送大的码流,但不占用过多的内存,防止JAVA内存溢出

                            ch.pipeline().addLast("http-chunked",

                                    new ChunkedWriteHandler());

                            ch.pipeline().addLast("httpServerHandler", new HttpServerHandler());

                        }

                    });

            ChannelFuture future = b.bind("localhost", port).sync();

            System.out.println("HTTP Server startup.");

            future.channel().closeFuture().sync();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            bossGroup.shutdownGracefully();

            workerGroup.shutdownGracefully();

        }

    }

    public static void main(String[] args) throws Exception {

        int port = 8080;

        new HttpServer().run(port);

    }

}

---

HttpServerHandler

package com.luangeng.netty.http;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelFutureListener;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.SimpleChannelInboundHandler;

import io.netty.handler.codec.http.*;

import io.netty.util.CharsetUtil;

import java.io.File;

import java.io.FileInputStream;

import java.net.URLDecoder;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_TYPE;

import static io.netty.handler.codec.http.HttpMethod.GET;

import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

/**

 * Created by LG on 2017/11/21.

 */

public class HttpServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

    private static final String BASE_DIR = System.getProperty("user.dir") + "/src/main/java/com/luangeng/netty/http/i";

    @Override

    protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {

        //

        if (!request.decoderResult().isSuccess()) {

            sendError(ctx, HttpResponseStatus.BAD_REQUEST);

            return;

        }

        //

        if (request.method() != GET) {

            sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED);

            return;

        }

        //

        String uri = request.uri();

        uri = URLDecoder.decode(uri, "UTF-8");

        uri = uri.replace('/', File.separatorChar);

        File file = new File(BASE_DIR + uri);

        if (!file.exists() || !file.isFile()) {

            sendError(ctx, HttpResponseStatus.NOT_FOUND);

            return;

        }

        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, HttpResponseStatus.OK);

        FileChannel channel = new FileInputStream(file).getChannel();

        ByteBuffer buffer = ByteBuffer.allocate(1024);

        while (channel.read(buffer) != -1) {

            buffer.flip();

            response.content().writeBytes(buffer);

            buffer.clear();

        }

        channel.close();

        if(uri.endsWith(".css")){

            response.headers().set(CONTENT_TYPE, "text/css; charset=UTF-8");

        }else {

            response.headers().set(CONTENT_TYPE, "text/html; charset=UTF-8");

        }

        long fileLength = response.content().readableBytes();

        HttpUtil.setContentLength(response, fileLength);

        ctx.writeAndFlush(response).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 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);

    }

}

---

hello.html

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Hello</title>

    <link rel="stylesheet" type="text/css" href="/back.css"/>

    <script src="/jquery-1.11.3.min.js"></script>

</head>

<body>

<div style="background:#98bf21;height:100px;width:100px;position:absolute;">

</div>

<p>

    一幅图像：

    <img src="/img1.jpg" width="128" height="128"/>

</p>

<p>

    一幅动画图像：

    <img id="img1" src="/eg_cute.gif" width="50" height="50"/>

</p>

<ul>

    <li>咖啡</li>

    <li>茶</li>

    <li>牛奶</li>

</ul>

</body>

<script type="text/javascript">

    $(document).ready(function() {

        timedCount();

    });

    function timedCount() {

        var div=$("div");

        div.animate({height:'300px',opacity:'0.4'},"slow");

        div.animate({width:'300px',opacity:'0.8'},"slow");

        div.animate({height:'100px',opacity:'0.4'},"slow");

        div.animate({width:'100px',opacity:'0.8'},"slow");

        t=setTimeout("timedCount()",5000)

    }

</script>

</html>

---

运行结果如下：

可见js，css，jpg等资源都可正常加载，

巴特西

Netty简单的HTTP服务器

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