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