实例：Netty 基于Http协议下的数据传输Demo

Http/Https协议是最重要最常用到的协议之一，Netty提供了一些了的Handler来处理Http协议下的编码工作。下面就介绍一个Netty实例：

1.通过HttpClient发送Protobuf类型数据到服务端

2.服务端Netty负责把接收到的Http请求中的数据再发送到客户端。

3.其中Netty对发送的数据量没有限制，因为Http发送的message往往是由一系列infragment构成，Netty可以把接收到的http请求片段信息整合（Aggregator）到一起，最终得到一个FullHttpRequest。

Client端：

package NettyDemo.echo.client;

import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.params.ConnRoutePNames;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import NettyDemo.echo.protocal.AddressBookProtos;
import NettyDemo.echo.server.HttpProtobufServer;

public class HttpClientDemo {
	public static void main(String[] args) throws ClientProtocolException,
			IOException {
		DefaultHttpClient httpclient = new DefaultHttpClient();
		HttpHost proxy = new HttpHost(HttpProtobufServer.IP,
				HttpProtobufServer.PORT);
		httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY,
				proxy);
		HttpPost httppost = new HttpPost("");
		AddressBookProtos.AddressBook.Builder address = AddressBookProtos.AddressBook
				.newBuilder();
		for (int i = 0; i < 20000; i++) {
			AddressBookProtos.Person.Builder person = AddressBookProtos.Person
					.newBuilder();
			person.setName("HeavenWang");
			person.setId(i);
			person.setEmail("wanghouda@126.com");
			address.addPerson(person);
		}
		ByteArrayEntity entity = new ByteArrayEntity(address.build().toByteArray());
		httppost.setEntity(entity);
		HttpResponse response = httpclient.execute(httppost);
		HttpEntity receiveEntity = response.getEntity();
		System.out.println("----------------------------------------");
		System.out.println(response.getStatusLine());
		if (receiveEntity != null) {
			System.out.println("Response content length: " + receiveEntity.getContentLength());
		}
		System.out.println("success");
	}
}

服务器端NettyService：

<span style="font-size:12px;">package NettyDemo.echo.server;

import io.netty.bootstrap.ServerBootstrap;
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.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpRequestDecoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
import io.netty.handler.codec.http.HttpServerCodec;
import NettyDemo.echo.handler.HttpProtobufServerHandler;

public class HttpProtobufServer {
	public static final String IP = "127.0.0.1";
	public static final int PORT = 8080;
	//private static MessageLite lite=AddressBookProtos.AddressBook.getDefaultInstance();
	/**用于分配处理业务线程的线程组个数 */
	protected static final int BIZGROUPSIZE = Runtime.getRuntime().availableProcessors()*2;	//默认
	/** 业务出现线程大小*/
	protected static final int BIZTHREADSIZE = 4;
	private static final EventLoopGroup bossGroup = new NioEventLoopGroup(BIZGROUPSIZE);
	private static final EventLoopGroup workerGroup = new NioEventLoopGroup(BIZTHREADSIZE);
	protected static void run() throws Exception {
		ServerBootstrap b = new ServerBootstrap();
		b.group(bossGroup, workerGroup);
		b.channel(NioServerSocketChannel.class);
		b.childHandler(new ChannelInitializer<SocketChannel>() {
			@Override
			public void initChannel(SocketChannel ch) throws Exception {
				ChannelPipeline pipeline = ch.pipeline();				
				pipeline.addLast("decoder", new HttpRequestDecoder());
				/**usually we receive http message infragment,if we want full http message,
				 * we should bundle HttpObjectAggregator and we can get FullHttpRequest。
				 * 我们通常接收到的是一个http片段，如果要想完整接受一次请求的所有数据，我们需要绑定HttpObjectAggregator，然后我们
				 * 就可以收到一个FullHttpRequest-是一个完整的请求信息。
				**/
				pipeline.addLast("servercodec",new HttpServerCodec());
				pipeline.addLast("aggegator",new HttpObjectAggregator(1024*1024*64));//定义缓冲数据量
				pipeline.addLast(new HttpProtobufServerHandler());
				pipeline.addLast("responseencoder",new HttpResponseEncoder());
			}
		});
		b.bind(IP, PORT).sync();
		System.out.println("TCP服务器已启动");
	}

	protected static void shutdown() {
		workerGroup.shutdownGracefully();
		bossGroup.shutdownGracefully();
	}

	public static void main(String[] args) throws Exception {
		System.out.println("开始启动http服务器...");
		HttpProtobufServer.run();
//		TcpServer.shutdown();
	}
}
</span>

Handler:

package NettyDemo.echo.handler;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpRequest;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;

public class HttpProtobufServerHandler extends SimpleChannelInboundHandler<Object>{
	@Override
	protected void channelRead0(ChannelHandlerContext ctx,	Object msg) throws Exception {
		DefaultFullHttpRequest request=(DefaultFullHttpRequest)msg;
		DefaultFullHttpResponse response=new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.ACCEPTED, request.content());
		ctx.writeAndFlush(response);
	}

	
}

附：FullHttpRequest构成，因此一个FullHttpRequest会包含请求message的所有片段。