Netty4.0学习笔记系列之三：构建简单的http服务

本文主要介绍如何通过Netty构建一个简单的http服务。

想要实现的目的是：

1、Client向Server发送http请求。

2、Server端对http请求进行解析。

3、Server端向client发送http响应。

4、Client对http响应进行解析。

在该实例中，会涉及到http请求的编码、解码，http响应的编码、解码，幸运的是，Netty已经为我们提供了这些工具，整个实例的逻辑图如下所示：

其中红色框中的4个类是Netty提供的，它们其实也是一种Handler，其中Encoder继承自ChannelOutboundHandler，Decoder继承自ChannelInboundHandler，它们的作用是：

1、HttpRequestEncoder：对httpRequest进行编码。

2、HttpRequestDecoder：把流数据解析为httpRequest。

3、HttpResponsetEncoder：对httpResponset进行编码。

4、HttpResponseEncoder：把流数据解析为httpResponse。

该实例涉及到的类有5个：HttpServer HttpServerInboundHandler HttpClient HttpClientInboundHandler ByteBufToBytes

1、HttpServer 启动http服务器

package com.guowl.testhttpprotocol;import io.netty.bootstrap.ServerBootstrap;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.NioServerSocketChannel;import io.netty.handler.codec.http.HttpRequestDecoder;import io.netty.handler.codec.http.HttpResponseEncoder;public class HttpServer {public void start(int port) throws Exception {EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)EventLoopGroup workerGroup = new NioEventLoopGroup();try {ServerBootstrap b = new ServerBootstrap(); // (2)b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) // (3).childHandler(new ChannelInitializer<SocketChannel>() { // (4)@Overridepublic void initChannel(SocketChannel ch) throws Exception {// server端发送的是httpResponse，所以要使用HttpResponseEncoder进行编码ch.pipeline().addLast(new HttpResponseEncoder());// server端接收到的是httpRequest，所以要使用HttpRequestDecoder进行解码ch.pipeline().addLast(new HttpRequestDecoder());ch.pipeline().addLast(new HttpServerInboundHandler());}}).option(ChannelOption.SO_BACKLOG, 128) // (5).childOption(ChannelOption.SO_KEEPALIVE, true); // (6)ChannelFuture f = b.bind(port).sync(); // (7)f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();bossGroup.shutdownGracefully();}}public static void main(String[] args) throws Exception {HttpServer server = new HttpServer();server.start(8000);}}

2、HttpServerInboundHandler 解析客户端的请求，并进行响应

package com.guowl.testhttpprotocol;import static io.netty.handler.codec.http.HttpHeaders.Names.CONNECTION;import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_LENGTH;import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_TYPE;import static io.netty.handler.codec.http.HttpResponseStatus.OK;import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;import io.netty.buffer.ByteBuf;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.HttpContent;import io.netty.handler.codec.http.HttpHeaders;import io.netty.handler.codec.http.HttpHeaders.Values;import io.netty.handler.codec.http.HttpRequest;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import com.guowl.utils.ByteBufToBytes;public class HttpServerInboundHandler extends ChannelInboundHandlerAdapter {private static Loggerlogger= LoggerFactory.getLogger(HttpServerInboundHandler.class);private ByteBufToBytes reader;@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {if (msg instanceof HttpRequest) {HttpRequest request = (HttpRequest) msg;System.out.println("messageType:" + request.headers().get("messageType"));System.out.println("businessType:" + request.headers().get("businessType"));if (HttpHeaders.isContentLengthSet(request)) {reader = new ByteBufToBytes((int) HttpHeaders.getContentLength(request));}}if (msg instanceof HttpContent) {HttpContent httpContent = (HttpContent) msg;ByteBuf content = httpContent.content();reader.reading(content);content.release();if (reader.isEnd()) {String resultStr = new String(reader.readFull());System.out.println("Client said:" + resultStr);FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK, Unpooled.wrappedBuffer("I am ok".getBytes()));response.headers().set(CONTENT_TYPE, "text/plain");response.headers().set(CONTENT_LENGTH, response.content().readableBytes());response.headers().set(CONNECTION, Values.KEEP_ALIVE);ctx.write(response);ctx.flush();}}}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) throws Exception {logger.info("HttpServerInboundHandler.channelReadComplete");ctx.flush();}}

3、HttpClient 向服务器发送请求

package com.guowl.testhttpprotocol;import io.netty.bootstrap.Bootstrap;import io.netty.buffer.Unpooled;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.DefaultFullHttpRequest;import io.netty.handler.codec.http.HttpHeaders;import io.netty.handler.codec.http.HttpMethod;import io.netty.handler.codec.http.HttpRequestEncoder;import io.netty.handler.codec.http.HttpResponseDecoder;import io.netty.handler.codec.http.HttpVersion;import java.net.URI;public class HttpClient {public void connect(String host, int port) throws Exception {EventLoopGroup workerGroup = new NioEventLoopGroup();try {Bootstrap b = new Bootstrap(); // (1)b.group(workerGroup); // (2)b.channel(NioSocketChannel.class); // (3)b.option(ChannelOption.SO_KEEPALIVE, true); // (4)b.handler(new ChannelInitializer<SocketChannel>() {@Overridepublic void initChannel(SocketChannel ch) throws Exception {// 客户端接收到的是httpResponse响应，所以要使用HttpResponseDecoder进行解码ch.pipeline().addLast(new HttpResponseDecoder());// 客户端发送的是httprequest，所以要使用HttpRequestEncoder进行编码ch.pipeline().addLast(new HttpRequestEncoder());ch.pipeline().addLast(new HttpClientInboundHandler());}});// Start the client.ChannelFuture f = b.connect(host, port).sync(); // (5)URI uri = new URI("http://127.0.0.1:8000");String msg = "Are you ok?";DefaultFullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.POST,uri.toASCIIString(), Unpooled.wrappedBuffer(msg.getBytes()));// 构建http请求request.headers().set(HttpHeaders.Names.HOST, host);request.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);request.headers().set(HttpHeaders.Names.CONTENT_LENGTH, request.content().readableBytes());request.headers().set("messageType", "normal");request.headers().set("businessType", "testServerState");// 发送http请求f.channel().write(request);f.channel().flush();f.channel().closeFuture().sync();} finally {workerGroup.shutdownGracefully();}}public static void main(String[] args) throws Exception {HttpClient client = new HttpClient();client.connect("127.0.0.1", 8000);}}

4、HttpClientInboundHandler 对服务器的响应进行读取

package com.guowl.testhttpprotocol;import io.netty.buffer.ByteBuf;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;import io.netty.handler.codec.http.HttpContent;import io.netty.handler.codec.http.HttpHeaders;import io.netty.handler.codec.http.HttpResponse;import com.guowl.utils.ByteBufToBytes;public class HttpClientInboundHandler extends ChannelInboundHandlerAdapter {private ByteBufToBytes reader;@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {if (msg instanceof HttpResponse) {HttpResponse response = (HttpResponse) msg;System.out.println("CONTENT_TYPE:" + response.headers().get(HttpHeaders.Names.CONTENT_TYPE));if (HttpHeaders.isContentLengthSet(response)) {reader = new ByteBufToBytes((int) HttpHeaders.getContentLength(response));}}if (msg instanceof HttpContent) {HttpContent httpContent = (HttpContent) msg;ByteBuf content = httpContent.content();reader.reading(content);content.release();if (reader.isEnd()) {String resultStr = new String(reader.readFull());System.out.println("Server said:" + resultStr);ctx.close();}}}}

5、ByteBufToBytes 读取NIO的工具类，可以一次性把ByteBuf的数据读取出来，也可以把多次ByteBuf中的数据统一读取出来。

package com.guowl.utils;import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;public class ByteBufToBytes {private ByteBuftemp;private booleanend= true;public ByteBufToBytes(int length) {temp = Unpooled.buffer(length);}public void reading(ByteBuf datas) {datas.readBytes(temp, datas.readableBytes());if (this.temp.writableBytes() != 0) {end = false;} else {end = true;}}public boolean isEnd() {return end;}public byte[] readFull() {if (end) {byte[] contentByte = new byte[this.temp.readableBytes()];this.temp.readBytes(contentByte);this.temp.release();return contentByte;} else {return null;}}public byte[] read(ByteBuf datas) {byte[] bytes = new byte[datas.readableBytes()];datas.readBytes(bytes);return bytes;}}

注意事项：

1、可以通过在Netty的Chanel中发送HttpRequest对象，完成发送http请求的要求，同时可以对HttpHeader进行设置。

2、可以通过HttpResponse发送http响应，同时可以对HttpHeader进行设置。

3、上面涉及到的http对象都是Netty自己封装的，不是标准的。