Netty(二) 创建简单的服务器

package com.tanoak.demo3.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.HttpServerCodec;

/** 
 * @author tanoak@qq.com
 * @date 2018/7/1 0:45    
 * @Desc
 */ 
public class HttpServer {

	public void start(final int port) throws Exception {
		EventLoopGroup boss = new NioEventLoopGroup();
		EventLoopGroup woker = new NioEventLoopGroup();
		ServerBootstrap serverBootstrap = new ServerBootstrap();

		try {
			serverBootstrap.channel(NioServerSocketChannel.class)
					.group(boss, woker)
					//测试链接的状态
					.childOption(ChannelOption.SO_KEEPALIVE, true)
					// 用来初始化服务端可连接队列，服务端处理客户端连接请求是顺序处理的；指定队列的大小
					.option(ChannelOption.SO_BACKLOG, 1024)
					.childHandler(new ChannelInitializer<SocketChannel>() {
						@Override
						protected void initChannel(SocketChannel ch) throws Exception {
							//重点  添加HttpServer
							ch.pipeline().addLast("http-decoder",new HttpServerCodec());
							//添加自定义的ChannelHandler
							ch.pipeline().addLast(new HttpServerHandler());
						}
					});

			ChannelFuture future = serverBootstrap.bind(port).sync();
			future.channel().closeFuture().sync();
		} finally {
			boss.shutdownGracefully();
			woker.shutdownGracefully();
		}
	}
	public static void main(String[] args) {
		try{
			System.out.println("服务器正在启动中");

			new HttpServer().start(8080);
		}catch (Exception e){
			System.out.println("服务器启动失败");
			e.printStackTrace();
		}
	}
}

基本的 I/O 操作（bind()、connect()、read()和 write()）依赖于底层网络传输所提
供的原语。在基于 Java 的网络编程中，其基本的构造是 class Socket。Netty 的 Channel 接口所提供的 API，大大地降低了直接使用 Socket 类的复杂性

EventLoop 定义了 Netty 的核心抽象，用于处理连接的生命周期中所发生的事件

package com.tanoak.demo3.server;

import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.*;

import java.util.HashMap;
import java.util.Map;

/**
 * @author 656443534@qq.com
 * @date 2018/7/1 0:12    
 * @Desc
 */ 
public class HttpServerHandler extends ChannelInboundHandlerAdapter {

	private static String yes = "<h1> this is yes Page </h1>";
	private static String  helloPage = "<h1> this is Hello wolrd page </h1>";
	private String error = "<h1>404</h1>访问入径不存在";
	private static Map<String, String> mapUrl = new HashMap<>();

	static {
		mapUrl.put("hello",helloPage) ;
		mapUrl.put("yes",yes) ;
	}

	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println("客户端连上了...");
	}

	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
		if (msg instanceof HttpRequest) {
			HttpRequest request = (HttpRequest) msg;
			boolean keepaLive = HttpUtil.isKeepAlive(request);
			System.out.println("访问的方式是：" + request.method()+"类型");
			System.out.println("访问的URI：" + request.uri());
			//获取访问的url
			String uri = request.uri().replace("/", "").trim();
			FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
			if(mapUrl.get(uri)!=null){
				response.content().writeBytes(mapUrl.get(uri).getBytes());
			}else{
				response.content().writeBytes(error.getBytes());
			}
			//重定向处理
			if (response.status().equals(HttpResponseStatus.FOUND)) {
				response.headers().set(HttpHeaderNames.LOCATION, "https://www.baidu.com/");
			}

			response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html;charset=UTF-8");
			response.headers().setInt(HttpHeaderNames.CONTENT_LENGTH, response.content().readableBytes());
			if (keepaLive) {
				response.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
				ctx.writeAndFlush(response);
			} else {
				ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
			}
		}
	}
	/**
	 *  有异常抛出时会调用。
	 * @param ctx
	 * @param cause
	 */
	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
		/**
		 * 并且关闭该 Channel
		 */

		System.out.println("发生了异常");
		cause.printStackTrace();
		ctx.close() ;
		System.out.println("已关闭ChannelHandlerContext");
	}

}