4.netty源码分析

1.pipeline调用handler的源码

//pipeline得到双向链表的头,next到尾部,

2.心跳源码 主要分析IdleStateHandler3个定时任务内部类
//考虑了网络传输慢导致出站慢的情况
//超时重新发送,然后关闭

ReadTimeoutHandler(继承IdleStateHandler 直接关闭连接)和WriteTimeoutHandler(继承ChannelOutboundHandlerAdapter 使用定时任务来完成)
//NioEventLoop进行事件循环

 @Overrideprotected void run() {for (;;) {try {switch (selectStrategy.calculateStrategy(selectNowSupplier, hasTasks())) {case SelectStrategy.CONTINUE:continue;case SelectStrategy.SELECT:select(wakenUp.getAndSet(false));if (wakenUp.get()) {selector.wakeup();}// fall throughdefault:}cancelledKeys = 0;needsToSelectAgain = false;final int ioRatio = this.ioRatio; //默认 50if (ioRatio == 100) { //如果被占用,就处理事件try {processSelectedKeys();} finally {// Ensure we always run tasks.runAllTasks(); //执行任务}} else {  //如果没有被占用final long ioStartTime = System.nanoTime();try {processSelectedKeys();  //选择一个key} finally {// Ensure we always run tasks.final long ioTime = System.nanoTime() - ioStartTime;runAllTasks(ioTime * (100 - ioRatio) / ioRatio);   //ioRatio默认是50 ,计算出来是1.所以定时任务执行了 ioTime没有响应的时间(妙啊,如果执行1s或者是其他时间那可能还是检测不到心跳)}}} catch (Throwable t) {handleLoopException(t);}// Always handle shutdown even if the loop processing threw an exception.try {if (isShuttingDown()) {closeAll();if (confirmShutdown()) {return;}}} catch (Throwable t) {handleLoopException(t);}}}

//IdleStateHandler

3.eventLoop执行定时任务的源代码(传入并执行队列)

1.select 默认阻塞1秒

4.任务加入异步线程池(处理耗时任务时)(因为执行任务读写 和执行读写后执行Loop任务是同一个线程)
就不会阻塞netty的IO

1.handler加入线程池(自己创建group线程池)
2.context加入线程池

/** Copyright 2012 The Netty Project** The Netty Project licenses this file to you under the Apache License,* version 2.0 (the "License"); you may not use this file except in compliance* with the License. You may obtain a copy of the License at:**   http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the* License for the specific language governing permissions and limitations* under the License.*/
package source.echo2;import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
import io.netty.util.concurrent.DefaultEventExecutorGroup;
import io.netty.util.concurrent.EventExecutorGroup;import java.util.concurrent.Callable;/*** Handler implementation for the echo server.*/
@Sharable
public class EchoServerHandler extends ChannelInboundHandlerAdapter {// group 就是充当业务线程池，可以将任务提交到该线程池// 这里我们创建了16个线程static final EventExecutorGroup group = new DefaultEventExecutorGroup(16);@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {System.out.println("EchoServer Handler 的线程是=" + Thread.currentThread().getName());//按照原来的方法处理耗时任务//解决方案2 用户程序自定义的普通任务ctx.channel().eventLoop().execute(new Runnable() {@Overridepublic void run() {try {Thread.sleep(5 * 1000);//输出线程名System.out.println("EchoServerHandler execute 线程是=" + Thread.currentThread().getName());ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵2", CharsetUtil.UTF_8));} catch (Exception ex) {System.out.println("发生异常" + ex.getMessage());}}});ctx.channel().eventLoop().execute(new Runnable() {@Overridepublic void run() {try {Thread.sleep(5 * 1000);//输出线程名System.out.println("EchoServerHandler execute 线程2是=" + Thread.currentThread().getName());ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵2", CharsetUtil.UTF_8));} catch (Exception ex) {System.out.println("发生异常" + ex.getMessage());}}});//方式1
//        //将任务提交到 group线程池
//        group.submit(new Callable<Object>() {
//            @Override
//            public Object call() throws Exception {
//
//                //接收客户端信息
                ByteBuf buf = (ByteBuf) msg;
                byte[] bytes = new byte[buf.readableBytes()];
                buf.readBytes(bytes);
                String body = new String(bytes, "UTF-8");
                //休眠10秒
                Thread.sleep(10 * 1000);
//                System.out.println("group.submit 的  call 线程是=" + Thread.currentThread().getName());
//                ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵2", CharsetUtil.UTF_8));
//                return null;
//
//            }
//        });
//
//        //将任务提交到 group线程池
//        group.submit(new Callable<Object>() {
//            @Override
//            public Object call() throws Exception {
//
//                //接收客户端信息
//                ByteBuf buf = (ByteBuf) msg;
//                byte[] bytes = new byte[buf.readableBytes()];
//                buf.readBytes(bytes);
//                String body = new String(bytes, "UTF-8");
//                //休眠10秒
//                Thread.sleep(10 * 1000);
//                System.out.println("group.submit 的  call 线程是=" + Thread.currentThread().getName());
//                ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵2", CharsetUtil.UTF_8));
//                return null;
//
//            }
//        });
//
//
//        //将任务提交到 group线程池
//        group.submit(new Callable<Object>() {
//            @Override
//            public Object call() throws Exception {
//
//                //接收客户端信息
//                ByteBuf buf = (ByteBuf) msg;
//                byte[] bytes = new byte[buf.readableBytes()];
//                buf.readBytes(bytes);
//                String body = new String(bytes, "UTF-8");
//                //休眠10秒
//                Thread.sleep(10 * 1000);
//                System.out.println("group.submit 的  call 线程是=" + Thread.currentThread().getName());
//                ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵2", CharsetUtil.UTF_8));
//                return null;
//
//            }
//        });//普通方式//接收客户端信息ByteBuf buf = (ByteBuf) msg;byte[] bytes = new byte[buf.readableBytes()];buf.readBytes(bytes);String body = new String(bytes, "UTF-8");//休眠10秒Thread.sleep(10 * 1000);System.out.println("普通调用方式的 线程是=" + Thread.currentThread().getName());ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵2", CharsetUtil.UTF_8));System.out.println("go on ");}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) {ctx.flush();}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {// Close the connection when an exception is raised.//cause.printStackTrace();ctx.close();}
}

5.netty源码
//面试

1.连接 ServerBootstrap空的构造器 作用为初始化类的成员
//启动bind

6.RPC(remote procedure call) call function like local machine

1.usual framework , ali Dubbo google gRPC ,Go rpcx
apache thrift ,spring cloud
pic 17.rpc procedure

7. imitate dubbo RPC 通过jdk反射实现

// server handler规定 msg开头是规定的字符串(或者协议)
msg.toString().startsWith(“helloService#hello”)
//callable可以在服务器和客户端之间使用,wait()然后notify() (在同一机器)
//read调用只一次,然后调用call(netty的pipeline自动调用)
//server和client,只需按照需要的名字来调用

//下面是客户端传递参数给服务端,然后服务端调用被代理的实现的接口

//创建消费者,调用远程服务

public class ClientBootstrap {//这里定义协议头(调用的方法名)public static final String providerName = "HelloService#hello#";public static void main(String[] args) throws  Exception{//创建一个消费者NettyClient customer = new NettyClient();//创建代理对象HelloService service = (HelloService) customer.getBean(HelloService.class, providerName);for (;;) {Thread.sleep(2 * 1000);//通过代理对象调用服务提供者的方法(服务)String res = service.hello("你好 dubbo~");System.out.println("调用的结果 res= " + res);}}
}

//创建客户端创建代理对象,和初始化客户端添加handler

public class NettyClient {//创建线程池private static ExecutorService executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());private static NettyClientHandler client;private int count = 0;//编写方法使用代理模式，获取一个代理对象public Object getBean(final Class<?> serivceClass, final String providerName) {return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),new Class<?>[]{serivceClass}, (proxy, method, args) -> {System.out.println("(proxy, method, args) 进入...." + (++count) + " 次");//{}  部分的代码，客户端每调用一次 hello, 就会进入到该代码if (client == null) {initClient();}//设置要发给服务器端的信息//providerName 协议头 args[0] 就是客户端调用api hello(???), 参数client.setPara(providerName + args[0]);return executor.submit(client).get();});}//初始化客户端private static void initClient() {client = new NettyClientHandler();//创建EventLoopGroupNioEventLoopGroup group = new NioEventLoopGroup();Bootstrap bootstrap = new Bootstrap();bootstrap.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true).handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ChannelPipeline pipeline = ch.pipeline();pipeline.addLast(new StringDecoder());pipeline.addLast(new StringEncoder());pipeline.addLast(client);}});try {bootstrap.connect("127.0.0.1", 7000).sync();} catch (Exception e) {e.printStackTrace();}}
}
//客户端handler,处理来自服务器的请求,服务器有数据通知线程,没有就等待public class NettyClientHandler extends ChannelInboundHandlerAdapter implements Callable {private ChannelHandlerContext context;//上下文private String result; //返回的结果private String para; //客户端调用方法时，传入的参数//与服务器的连接创建后，就会被调用, 这个方法是第一个被调用(1)@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {System.out.println(" channelActive 被调用  ");context = ctx; //因为我们在其它方法会使用到 ctx}//收到服务器的数据后，调用方法 (4)//@Overridepublic synchronized void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {System.out.println(" channelRead 被调用  ");result = msg.toString();notify(); //服务器返回数据,唤醒等待的线程}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {ctx.close();}//被代理对象调用, 发送数据给服务器，-> wait -> 等待被唤醒(channelRead) -> 返回结果 (3)-》5@Overridepublic synchronized Object call() throws Exception {System.out.println(" call1 被调用  ");context.writeAndFlush(para); //这里的context是client自己的,//进行waitwait(); //等待channelRead 方法获取到服务器的结果后，唤醒System.out.println(" call2 被调用  ");return  result; //服务方返回的结果}//(2)void setPara(String para) {System.out.println(" setPara  ");this.para = para;}
}

//创建服务器端,添加服务器handler

public class NettyServer {public static void startServer(String hostName, int port) {startServer0(hostName,port);}//编写一个方法，完成对NettyServer的初始化和启动private static void startServer0(String hostname, int port) {EventLoopGroup bossGroup = new NioEventLoopGroup(1);EventLoopGroup workerGroup = new NioEventLoopGroup();try {ServerBootstrap serverBootstrap = new ServerBootstrap();serverBootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ChannelPipeline pipeline = ch.pipeline();pipeline.addLast(new StringDecoder());pipeline.addLast(new StringEncoder());pipeline.addLast(new NettyServerHandler()); //业务处理器}});ChannelFuture channelFuture = serverBootstrap.bind(hostname, port).sync();System.out.println("服务提供方开始提供服务~~");channelFuture.channel().closeFuture().sync();}catch (Exception e) {e.printStackTrace();}finally {bossGroup.shutdownGracefully();workerGroup.shutdownGracefully();}}public static void main(String[] args) {//代码代填..NettyServer.startServer("127.0.0.1", 7000);}
}
//服务器handler,如果接收到客户端的请求,得到字符,传入参数调用实现类方法public class NettyServerHandler extends ChannelInboundHandlerAdapter {@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {//获取客户端发送的消息，并调用服务System.out.println("msg=" + msg);//客户端在调用服务器的api 时，我们需要定义一个协议//比如我们要求 每次发消息是都必须以某个字符串开头 "HelloService#hello#你好"if(msg.toString().startsWith(ClientBootstrap.providerName)) {msg.toString().lastIndexOf("#")String substring = msg.toString().substring(msg.toString().lastIndexOf("#") + 1);String result = new HelloServiceImpl().hello(substring);ctx.writeAndFlush(result); //向客户端写回返回的结果}}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {ctx.close();}
}

//接口(客户端需要,使用jdk代理可以代理接口,使用cglib可以直接代理类)
//这个是接口，是服务提供方和 服务消费方都需要

public interface HelloService {String hello(String mes);
}//实现类
public class HelloServiceImpl implements HelloService {private static int count = 0;//当有消费方调用该方法时， 就返回一个结果@Overridepublic String hello(String mes) {System.out.println("收到客户端消息=" + mes);//根据mes 返回不同的结果if(mes != null) {return "你好客户端, 我已经收到你的消息 [" + mes + "] 第" + (++count) + " 次";} else {return "你好客户端, 我已经收到你的消息 ";}}
}