Netty 是一个基于 JAVA NIO 类库的异步通信框架，它的架构特点是：异步非阻塞、基于事件驱动、高性能、高可靠性和高可定制性。换句话说，Netty是一个NIO框架，使用它可以简单快速地开发网络应用程序，比如客户端和服务端的协议。Netty大大简化了网络程序的开发过程比如TCP和UDP的 Socket的开发。Netty 已逐渐成为 Java NIO 编程的首选框架，Netty中，通讯的双方建立连接后，会把数据按照ByteBuf的方式进行传输，因此我们在构建Http服务器的时候就是通过HttpRequestDecoder对ByteBuf数据流进行处理，转换成http的对象。代码如下：
maven依赖
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.0.Final</version>
</dependency>
HttpServer类
package com.example.demo.netty; import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelPipeline; 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.HttpServerCodec; public class HttpServer { public static void main(String[] args) throws InterruptedException { 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 { ChannelPipeline pipeline = ch.pipeline(); pipeline.addLast(new HttpServerCodec()); pipeline.addLast(new HttpServerHandler()); } }); ChannelFuture f = b.bind(8080).sync(); f.channel().closeFuture().sync(); } finally { workerGroup.shutdownGracefully(); bossGroup.shutdownGracefully(); } } }
HttpServerHandler类
package com.example.demo.netty; import java.io.UnsupportedEncodingException; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import io.netty.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpResponse; import io.netty.handler.codec.http.HttpRequest; import io.netty.handler.codec.http.HttpResponseStatus; import io.netty.handler.codec.http.HttpVersion; import io.netty.handler.codec.http.QueryStringDecoder; class HttpServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws UnsupportedEncodingException { if (msg instanceof HttpRequest) { // 请求，解码器将请求转换成HttpRequest对象 HttpRequest request = (HttpRequest) msg; // 获取请求参数 QueryStringDecoder queryStringDecoder = new QueryStringDecoder(request.uri()); String name = "netty"; if(queryStringDecoder.parameters().get("name") != null) { name = queryStringDecoder.parameters().get("name").get(0); } // 响应HTML String responseHtml = "<html><body>Hello, " + name + "</body></html>"; byte[] responseBytes = responseHtml.getBytes("UTF-8"); int contentLength = responseBytes.length; // 构造FullHttpResponse对象，FullHttpResponse包含message body FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK, Unpooled.wrappedBuffer(responseBytes)); response.headers().set("Content-Type", "text/html; charset=utf-8"); response.headers().set("Content-Length", Integer.toString(contentLength)); ctx.writeAndFlush(response); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { cause.printStackTrace(); ctx.close(); } }
运行HttpServer中main方法，启动httpServer，打开浏览器输入http://localhost:8080?name=zhangsan ，结果如下：
