RabbitMQ深度探索：简单实现 MQ

基于多线程队列实现 MQ ：

1. 实现类：

   public class ThreadMQ {private static LinkedBlockingDeque<JSONObject> broker = new LinkedBlockingDeque<JSONObject>();public static void main(String[] args) {//创建生产者线程Thread producer = new Thread(new Runnable() {@Overridepublic void run() {while (true){try {Thread.sleep(1000);JSONObject data = new JSONObject();data.put("phone","11111111");broker.offer(data);}catch (Exception e){}}}},"生产者");producer.start();Thread consumer = new Thread(new Runnable() {@Overridepublic void run() {while (true){try {JSONObject data = broker.poll();if(data != null){System.out.println(Thread.currentThread().getName() + data.toJSONString());}}catch (Exception e){}}}},"消费者");consumer.start();}
   }

基于 netty 实现 MQ：

1. 执行过程：

   1. 消费者 netty 客户端与 nettyServer 端 MQ 服务器保持长连接，MQ 服务器端保存消费者连接
   2. 生产者 netty 客户端发送请求给 nettyServer 端 MQ 服务器，MQ 服务器端再将消息内容发送给消费者

2. 执行流程：

   1. 导入 Maven 依赖：

      <dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.62</version>
      </dependency>
      <dependency><groupId>io.netty</groupId><artifactId>netty-all</artifactId><version>4.0.23.Final</version>
      </dependency>
      <dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.62</version>
      </dependency>
      <dependency><groupId>org.apache.commons</groupId><artifactId>commons-lang3</artifactId><version>3.11</version>
      </dependency>
      <dependency><groupId>com.rabbitmq</groupId><artifactId>amqp-client</artifactId><version>3.6.5</version>
      </dependency>

   2. 服务端：

      package com.qcby.springboot.MQ;import com.alibaba.fastjson.JSONObject;
      import io.netty.bootstrap.ServerBootstrap;
      import io.netty.buffer.ByteBuf;
      import io.netty.buffer.Unpooled;
      import io.netty.channel.*;
      import io.netty.channel.nio.NioEventLoopGroup;
      import io.netty.channel.socket.SocketChannel;
      import io.netty.channel.socket.nio.NioServerSocketChannel;
      import org.apache.commons.lang3.StringUtils;import java.io.UnsupportedEncodingException;
      import java.util.ArrayList;
      import java.util.concurrent.LinkedBlockingDeque;/*** @ClassName BoyatopMQServer2021* @Author* @Version V1.0**/
      public class BoyatopNettyMQServer {public void bind(int port) throws Exception {/*** Netty 抽象出两组线程池BossGroup和WorkerGroup* BossGroup专门负责接收客户端的连接, WorkerGroup专门负责网络的读写。*/EventLoopGroup bossGroup = new NioEventLoopGroup();EventLoopGroup workerGroup = new NioEventLoopGroup();ServerBootstrap bootstrap = new ServerBootstrap();try {bootstrap.group(bossGroup, workerGroup)// 设定NioServerSocketChannel 为服务器端.channel(NioServerSocketChannel.class)//BACKLOG用于构造服务端套接字ServerSocket对象，标识当服务器请求处理线程全满时，//用于临时存放已完成三次握手的请求的队列的最大长度。如果未设置或所设置的值小于1，Java将使用默认值50。.option(ChannelOption.SO_BACKLOG, 100)// 服务器端监听数据回调Handler.childHandler(new BoyatopNettyMQServer.ChildChannelHandler());//绑定端口, 同步等待成功;ChannelFuture future = bootstrap.bind(port).sync();System.out.println("当前服务器端启动成功...");//等待服务端监听端口关闭future.channel().closeFuture().sync();} catch (Exception e) {e.printStackTrace();} finally {//优雅关闭 线程组bossGroup.shutdownGracefully();workerGroup.shutdownGracefully();}}private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {// 设置异步回调监听ch.pipeline().addLast(new BoyatopNettyMQServer.MayiktServerHandler());}}public static void main(String[] args) throws Exception {int port = 9008;new BoyatopNettyMQServer().bind(port);}private static final String type_consumer = "consumer";private static final String type_producer = "producer";private static LinkedBlockingDeque<String> msgs = new LinkedBlockingDeque<>();private static ArrayList<ChannelHandlerContext> ctxs = new ArrayList<>();// 生产者投递消息的：topicNamepublic class MayiktServerHandler extends SimpleChannelInboundHandler<Object> {/*** 服务器接收客户端请求** @param ctx* @param data* @throws Exception*/@Overrideprotected void channelRead0(ChannelHandlerContext ctx, Object data)throws Exception {//ByteBuf buf=(ByteBuf)data;//byte[] req = new byte[buf.readableBytes()];//buf.readBytes(req);//String body = new String(req, "UTF-8");//System.out.println("body:"+body);JSONObject clientMsg = getData(data);String type = clientMsg.getString("type");switch (type) {case type_producer:producer(clientMsg);break;case type_consumer:consumer(ctx);break;}}private void consumer(ChannelHandlerContext ctx) {// 保存消费者连接ctxs.add(ctx);// 主动拉取mq服务器端缓存中没有被消费的消息String data = msgs.poll();if (StringUtils.isEmpty(data)) {return;}// 将该消息发送给消费者byte[] req = data.getBytes();ByteBuf firstMSG = Unpooled.buffer(req.length);firstMSG.writeBytes(req);ctx.writeAndFlush(firstMSG);}private void producer(JSONObject clientMsg) {// 缓存生产者投递 消息String msg = clientMsg.getString("msg");msgs.offer(msg); //保证消息不丢失还可以缓存硬盘//需要将该消息推送消费者ctxs.forEach((ctx) -> {// 将该消息发送给消费者String data = msgs.poll();if (data == null) {return;}byte[] req = data.getBytes();ByteBuf firstMSG = Unpooled.buffer(req.length);firstMSG.writeBytes(req);ctx.writeAndFlush(firstMSG);});}private JSONObject getData(Object data) throws UnsupportedEncodingException {ByteBuf buf = (ByteBuf) data;byte[] req = new byte[buf.readableBytes()];buf.readBytes(req);String body = new String(req, "UTF-8");return JSONObject.parseObject(body);}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) throws Exception {ctx.flush();}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)throws Exception {ctx.close();}}
      }

   3. 生产端：

      package com.qcby.springboot.MQ;import com.alibaba.fastjson.JSONObject;
      import io.netty.bootstrap.Bootstrap;
      import io.netty.buffer.ByteBuf;
      import io.netty.buffer.Unpooled;
      import io.netty.channel.*;
      import io.netty.channel.nio.NioEventLoopGroup;
      import io.netty.channel.socket.SocketChannel;
      import io.netty.channel.socket.nio.NioSocketChannel;/*** @ClassName BoyatopNettyMQProducer* @Author* @Version V1.0**/
      public class BoyatopNettyMQProducer {public void connect(int port, String host) throws Exception {//配置客户端NIO 线程组EventLoopGroup group = new NioEventLoopGroup();Bootstrap client = new Bootstrap();try {client.group(group)// 设置为Netty客户端.channel(NioSocketChannel.class)/*** ChannelOption.TCP_NODELAY参数对应于套接字选项中的TCP_NODELAY,该参数的使用与Nagle算法有关。* Nagle算法是将小的数据包组装为更大的帧然后进行发送，而不是输入一次发送一次，因此在数据包不足的时候会等待其他数据的到来，组装成大的数据包进行发送，虽然该算法有效提高了网络的有效负载，但是却造成了延时。* 而该参数的作用就是禁止使用Nagle算法，使用于小数据即时传输。和TCP_NODELAY相对应的是TCP_CORK，该选项是需要等到发送的数据量最大的时候，一次性发送数据，适用于文件传输。*/.option(ChannelOption.TCP_NODELAY, true).handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new BoyatopNettyMQProducer.NettyClientHandler());1. 演示LineBasedFrameDecoder编码器
      //                            ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
      //                            ch.pipeline().addLast(new StringDecoder());}});//绑定端口, 异步连接操作ChannelFuture future = client.connect(host, port).sync();//等待客户端连接端口关闭future.channel().closeFuture().sync();} finally {//优雅关闭 线程组group.shutdownGracefully();}}public static void main(String[] args) {int port = 9008;BoyatopNettyMQProducer client = new BoyatopNettyMQProducer();try {client.connect(port, "127.0.0.1");} catch (Exception e) {e.printStackTrace();}}public class NettyClientHandler extends ChannelInboundHandlerAdapter {@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {JSONObject data = new JSONObject();data.put("type", "producer");JSONObject msg = new JSONObject();msg.put("userId", "123456");msg.put("age", "23");data.put("msg", msg);// 生产发送数据byte[] req = data.toJSONString().getBytes();ByteBuf firstMSG = Unpooled.buffer(req.length);firstMSG.writeBytes(req);ctx.writeAndFlush(firstMSG);}/*** 客户端读取到服务器端数据** @param ctx* @param msg* @throws Exception*/@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {ByteBuf buf = (ByteBuf) msg;byte[] req = new byte[buf.readableBytes()];buf.readBytes(req);String body = new String(req, "UTF-8");System.out.println("客户端接收到服务器端请求:" + body);}// tcp属于双向传输@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {ctx.close();}}
      }

   4. 客户端：

      package com.qcby.springboot.MQ;import com.alibaba.fastjson.JSONObject;
      import io.netty.bootstrap.Bootstrap;
      import io.netty.buffer.ByteBuf;
      import io.netty.buffer.Unpooled;
      import io.netty.channel.*;
      import io.netty.channel.nio.NioEventLoopGroup;
      import io.netty.channel.socket.SocketChannel;
      import io.netty.channel.socket.nio.NioSocketChannel;/*** @ClassName BoyatopNettyMQProducer* @Author* @Version V1.0**/
      public class NettyMQConsumer {public void connect(int port, String host) throws Exception {//配置客户端NIO 线程组EventLoopGroup group = new NioEventLoopGroup();Bootstrap client = new Bootstrap();try {client.group(group)// 设置为Netty客户端.channel(NioSocketChannel.class)/*** ChannelOption.TCP_NODELAY参数对应于套接字选项中的TCP_NODELAY,该参数的使用与Nagle算法有关。* Nagle算法是将小的数据包组装为更大的帧然后进行发送，而不是输入一次发送一次，因此在数据包不足的时候会等待其他数据的到来，组装成大的数据包进行发送，虽然该算法有效提高了网络的有效负载，但是却造成了延时。* 而该参数的作用就是禁止使用Nagle算法，使用于小数据即时传输。和TCP_NODELAY相对应的是TCP_CORK，该选项是需要等到发送的数据量最大的时候，一次性发送数据，适用于文件传输。*/.option(ChannelOption.TCP_NODELAY, true).handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new NettyMQConsumer.NettyClientHandler());1. 演示LineBasedFrameDecoder编码器
      //                            ch.pipeline().addLast(new LineBasedFrameDecoder(1024));
      //                            ch.pipeline().addLast(new StringDecoder());}});//绑定端口, 异步连接操作ChannelFuture future = client.connect(host, port).sync();//等待客户端连接端口关闭future.channel().closeFuture().sync();} finally {//优雅关闭 线程组group.shutdownGracefully();}}public static void main(String[] args) {int port = 9008;NettyMQConsumer client = new NettyMQConsumer();try {client.connect(port, "127.0.0.1");} catch (Exception e) {e.printStackTrace();}}public class NettyClientHandler extends ChannelInboundHandlerAdapter {@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {JSONObject data = new JSONObject();data.put("type", "consumer");// 生产发送数据byte[] req = data.toJSONString().getBytes();ByteBuf firstMSG = Unpooled.buffer(req.length);firstMSG.writeBytes(req);ctx.writeAndFlush(firstMSG);}/*** 客户端读取到服务器端数据** @param ctx* @param msg* @throws Exception*/@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {ByteBuf buf = (ByteBuf) msg;byte[] req = new byte[buf.readableBytes()];buf.readBytes(req);String body = new String(req, "UTF-8");System.out.println("客户端接收到服务器端请求:" + body);}// tcp属于双向传输@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {ctx.close();}}
      }

3. 持久化机制：

   1. 如果 MQ 接收到生产者投递信息，如果消费者不存在的情况下，消息是否会丢失？
   2. 答：不会丢失，消息确认机制必须要消费者消费成功之后，在通知给 MQ 服务器端，删除该消息

4. MQ 服务器将该消息推送给消费者：

   1. 消费者已经和 MQ 服务器保持长连接
   2. 消费者在第一次启动的时候会主动拉取信息

5. MQ 如何实现高并发思想：

   1. MQ 消费者根据自身能力情况，拉取 MQ 服务器端消费消息
   2. 默认的情况下取出一条消息

6. 缺点：

   1. 存在延迟问题

7. 需要考虑 MQ 消费者提高速率的问题：

   1. 如何提高消费者速率：消费者实现集群、消费者批量获取消息即可