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 { ???????//400 ???????if (!request.decoderResult().isSuccess()) { ???????????sendError(ctx, HttpResponseStatus.BAD_REQUEST); ???????????return; ???????} ???????//405 ???????if (request.method() != GET) { ???????????sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED); ???????????return; ???????} ???????//404 ???????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，
参考：Netty权威指南
end
Netty 开发HTTP服务端应用
原文地址：http://www.cnblogs.com/luangeng/p/7875710.html