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.java、HttpServerInboundHandler.java、HttpClient.java、HttpClientInboundHandler.java、ByteBufToBytes.java

1.HttpServer启动http服务器

package com.bijian.netty.server;

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)
                                @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) // (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.bijian.netty.server;

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.bijian.netty.util.ByteBufToBytes;

public class HttpServerInboundHandler extends ChannelInboundHandlerAdapter {
    
    private static Logger logger = LoggerFactory.getLogger(HttpServerInboundHandler.class);
    private ByteBufToBytes reader;

    @Override
    public 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();
            }
        }
    }

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

3.HttpClient 向服务器发送请求

package com.bijian.netty.client;

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>() {
                @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(); // (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.bijian.netty.client;

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.bijian.netty.util.ByteBufToBytes;

public class HttpClientInboundHandler extends ChannelInboundHandlerAdapter {
    
    private ByteBufToBytes reader;

    @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 (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.bijian.netty.util;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;

public class ByteBufToBytes {
    
    private ByteBuf temp;

    private boolean end = 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。

 

文章来源：http://blog.csdn.net/u013252773/article/details/21254257