基于Netty4的HttpServer和HttpClient的简单实现

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J2EE

Http 消息格式：

Http request:

Method path-to-resource HTTPVersion-number
Header-name-1: value1
Header-name-2: value2

Optional request body

Http response:

HTTP/Version-number response-code response-phrase 
Header-name-1: value1
Header-name-2: value2

Optional response body

实现一个简单的Http请求及响应过程：

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。

Netty中Http request消息格式：

Netty中Http response消息格式：

代码实例：

Http Server：

package com.netty.test;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

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 {

    private static Log log = LogFactory.getLog(HttpServer.class);
    
    public void start(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
                                public 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) 
                    .childOption(ChannelOption.SO_KEEPALIVE, true);

            ChannelFuture f = b.bind(port).sync();

            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        HttpServer server = new HttpServer();
        log.info("Http Server listening on 8844 ...");
        server.start(8844);
    }
}

响应请求的HttpServerInboundHandler：

package com.netty.test;

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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

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;

public class HttpServerInboundHandler extends ChannelInboundHandlerAdapter {

    private static Log log = LogFactory.getLog(HttpServerInboundHandler.class);

    private HttpRequest request;

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        if (msg instanceof HttpRequest) {
            request = (HttpRequest) msg;

            String uri = request.getUri();
            System.out.println("Uri:" + uri);
        }
        if (msg instanceof HttpContent) {
            HttpContent content = (HttpContent) msg;
            ByteBuf buf = content.content();
            System.out.println(buf.toString(io.netty.util.CharsetUtil.UTF_8));
            buf.release();

            String res = "I am OK";
            FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1,
                    OK, Unpooled.wrappedBuffer(res.getBytes("UTF-8")));
            response.headers().set(CONTENT_TYPE, "text/plain");
            response.headers().set(CONTENT_LENGTH,
                    response.content().readableBytes());
            if (HttpHeaders.isKeepAlive(request)) {
                response.headers().set(CONNECTION, Values.KEEP_ALIVE);
            }
            ctx.write(response);
            ctx.flush();
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        log.error(cause.getMessage());
        ctx.close();
    }

}

Http Client：

package com.netty.test;

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();
            b.group(workerGroup);
            b.channel(NioSocketChannel.class);
            b.option(ChannelOption.SO_KEEPALIVE, true);
            b.handler(new ChannelInitializer<SocketChannel>() {
                @Override
                public 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();

            URI uri = new URI("http://127.0.0.1:8844");
            String msg = "Are you ok?";
            DefaultFullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET,
                    uri.toASCIIString(), Unpooled.wrappedBuffer(msg.getBytes("UTF-8")));

            // 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());
            // 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", 8844);
    }
}

处理Server响应的HttpClientInboundHandler：

package com.netty.test;

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;

public class HttpClientInboundHandler extends ChannelInboundHandlerAdapter {

    @Override
    public 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(msg instanceof HttpContent)
        {
            HttpContent content = (HttpContent)msg;
            ByteBuf buf = content.content();
            System.out.println(buf.toString(io.netty.util.CharsetUtil.UTF_8));
            buf.release();
        }
    }
}

参考代码：https://github.com/luxiaoxun/Code4Java