前言

之前,我们写了通信协议的具体设计,接下来我们设计服务器类

设计思想

我们先只考虑一个虚拟主机的情况下, 在一个虚拟主机的情况下,我们需要有一个session会话来帮助我们存储信息,并且既然是网络通信,那么socket关键字肯定也必不可少,我们在引入一个线程池,用来处理多个客户端的请求

  private ServerSocket serverSocket = null;// 当前考虑一个 BrokerServer 上只有一个 虚拟主机private VirtuaHost virtualHost = new VirtuaHost("default");// 使用这个 哈希表 表示当前的所有会话(也就是说有哪些客户端正在和咱们的服务器进行通信)// 此处的 key 是 channelId, value 为对应的 Socket 对象private ConcurrentHashMap<String, Socket> sessions = new ConcurrentHashMap<String, Socket>();// 引入一个线程池, 来处理多个客户端的请求.private ExecutorService executorService = null;// 引入一个 boolean 变量控制服务器是否继续运行private volatile boolean runnable = true;

代码实现

package com.example.demo.mqServer;import com.example.demo.Common.*;
import com.example.demo.mqServer.core.BasicProperties;import javax.websocket.Session;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;/* 消息队列的本体服务器, 是TCP服务器 */
public class BrokerServer {private ServerSocket serverSocket = null;// 当前考虑一个 BrokerServer 上只有一个 虚拟主机private VirtuaHost virtualHost = new VirtuaHost("default");// 使用这个 哈希表 表示当前的所有会话(也就是说有哪些客户端正在和咱们的服务器进行通信)// 此处的 key 是 channelId, value 为对应的 Socket 对象private ConcurrentHashMap<String, Socket> sessions = new ConcurrentHashMap<String, Socket>();// 引入一个线程池, 来处理多个客户端的请求.private ExecutorService executorService = null;// 引入一个 boolean 变量控制服务器是否继续运行private volatile boolean runnable = true;public  BrokerServer (int port) throws IOException {serverSocket = new ServerSocket(port);}// 开始服务器public void start() throws IOException {System.out.println("[BrokerServer] 启动!");executorService = Executors.newCachedThreadPool();try {while (runnable) {Socket clientSocket = serverSocket.accept();// 把处理连接的逻辑丢给这个线程池.executorService.submit(() -> {processConnection(clientSocket);});}} catch (SocketException e) {System.out.println("[BrokerServer] 服务器停止运行!");// e.printStackTrace();}}// 停止服务器public void stop() throws IOException {runnable=false;executorService.shutdownNow();serverSocket.close();}// 处理一个客户端的链接// 在这一个链接中, 可能会涉及到多个请求和响应private void processConnection(Socket clientSocket) {try (InputStream inputStream = clientSocket.getInputStream();OutputStream outputStream = clientSocket.getOutputStream()){try (DataInputStream dataInputStream = new DataInputStream(inputStream);DataOutputStream dataOutputStream = new DataOutputStream(outputStream)){while (true){// 1 读取请求并解析Request request = readRequest(dataInputStream);// 2 根据请求计算响应Response response = process(request, clientSocket);// 3. 把响应写回给客户端writeResponse(dataOutputStream, response);}} catch (EOFException | SocketException e) {// 对于这个代码, DataInputStream 如果读到 EOF , 就会抛出一个 EOFException 异常.// 需要借助这个异常来结束循环System.out.println("[BrokerServer] connection 关闭! 客户端的地址: " + clientSocket.getInetAddress().toString()+ ":" + clientSocket.getPort());} catch (ClassNotFoundException | MqException e) {e.printStackTrace();}} catch (IOException e) {System.out.println("[BrokerServer] connection 出现异常!");e.printStackTrace();} finally {try {// 当连接处理完了, 就需要记得关闭 socketclientSocket.close();// 一个 TCP 连接中, 可能包含多个 channel. 需要把当前这个 socket 对应的所有 channel 也顺便清理掉.clearClosedSession(clientSocket);} catch (IOException e) {e.printStackTrace();}}}private Request readRequest(DataInputStream dataInputStream) throws IOException {Request request = new Request();request.setType(dataInputStream.readInt());request.setLength(dataInputStream.readInt());byte[] payload = new byte[request.getLength()];int n = dataInputStream.read(payload);if (n != request.getLength()) {throw new IOException("读取请求格式出错!");}request.setPayload(payload);return request;}private void writeResponse(DataOutputStream dataOutputStream, Response response) throws IOException {dataOutputStream.writeInt(response.getType());dataOutputStream.writeInt(response.getLength());dataOutputStream.write(response.getPayload());// 这个刷新缓冲区也是重要的操作!!dataOutputStream.flush();}private Response process(Request request, Socket clientSocket) throws IOException, ClassNotFoundException, MqException {// 1. 把 request 中的 payload 做一个初步的解析.BasicArguments basicArguments = (BasicArguments) BinaryTool.toObject(request.getPayload());System.out.println("[Request] rid=" + basicArguments.getRid() + ", channelId=" + basicArguments.getChannelId()+ ", type=" + request.getType() + ", length=" + request.getLength());// 2. 根据 type 的值, 来进一步区分接下来这次请求要干啥.boolean ok = true;if (request.getType() == 0x1) {// 创建 channelsessions.put(basicArguments.getChannelId(), clientSocket);System.out.println("[BrokerServer] 创建 channel 完成! channelId=" + basicArguments.getChannelId());} else if (request.getType() == 0x2) {// 销毁 channelsessions.remove(basicArguments.getChannelId());System.out.println("[BrokerServer] 销毁 channel 完成! channelId=" + basicArguments.getChannelId());} else if (request.getType() == 0x3) {// 创建交换机. 此时 payload 就是 ExchangeDeclareArguments 对象了.ExchangeDeclareArguments arguments = (ExchangeDeclareArguments) basicArguments;ok = virtualHost.exchangeDeclare(arguments.getExchangeName(), arguments.getExchangeType(),arguments.isDurable(), arguments.isAutoDelete(), arguments.getArguments());} else if (request.getType() == 0x4) {ExchangeDeleteArguments arguments = (ExchangeDeleteArguments) basicArguments;ok = virtualHost.exchangeDelete(arguments.getExchangeName());} else if (request.getType() == 0x5) {QueueDeclareArguments arguments = (QueueDeclareArguments) basicArguments;ok = virtualHost.queueDeclare(arguments.getQueueName(), arguments.isDurable(),arguments.isExclusive(), arguments.isAutoDelete(), arguments.getArguments());} else if (request.getType() == 0x6) {QueueDeleteArguments arguments = (QueueDeleteArguments) basicArguments;ok = virtualHost.queueDelete((arguments.getQueueName()));} else if (request.getType() == 0x7) {QueueBindArguments arguments = (QueueBindArguments) basicArguments;ok = virtualHost.queueBind(arguments.getQueueName(), arguments.getExchangeName(), arguments.getBindingKey());} else if (request.getType() == 0x8) {QueueUnbindArguments arguments = (QueueUnbindArguments) basicArguments;ok = virtualHost.queueUnbind(arguments.getQueueName(), arguments.getExchangeName());} else if (request.getType() == 0x9) {BasicPublishArguments arguments = (BasicPublishArguments) basicArguments;ok = virtualHost.basicPublish(arguments.getExchangeName(), arguments.getRoutingKey(),arguments.getBasicProperties(), arguments.getBody());} else if (request.getType() == 0xa) {BasicConsumeArguments arguments = (BasicConsumeArguments) basicArguments;ok = virtualHost.basicConsume(arguments.getConsumerTag(), arguments.getQueueName(), arguments.isAutoAck(),new Consumer() {// 这个回调函数要做的工作, 就是把服务器收到的消息可以直接推送回对应的消费者客户端@Overridepublic void handleDelivery(String consumerTag, BasicProperties basicProperties, byte[] body) throws MqException, IOException {// 先知道当前这个收到的消息, 要发给哪个客户端.// 此处 consumerTag 其实是 channelId. 根据 channelId 去 sessions 中查询, 就可以得到对应的// socket 对象了, 从而可以往里面发送数据了// 1. 根据 channelId 找到 socket 对象Socket clientSockte = sessions.get(consumerTag);if (clientSocket == null || clientSocket.isClosed()) {throw new MqException("[BrokerServer] 订阅消息的客户端已经关闭!");}SubScribeReturns subScribeReturns = new SubScribeReturns();subScribeReturns.setChannelId(consumerTag);subScribeReturns.setRid("");subScribeReturns.setOk(true);subScribeReturns.setConsumerTag(consumerTag);subScribeReturns.setBody(body);subScribeReturns.setBasicProperties(basicProperties);byte[] payload = BinaryTool.toBytes(subScribeReturns);// 2. 构造响应数据Response response = new Response();// oxc 服务器给消费者客户端托送的消息数据response.setType(0xc);// response 的 payload 就是一个 SubScribeReturnsresponse.setLength(payload.length);response.setPayload(payload);// 把数据写回到客户端 , 写入到响应之中DataOutputStream dataOutputStream = new DataOutputStream(clientSockte.getOutputStream());writeResponse(dataOutputStream,response);}});} else if (request.getType() == 0xb) {// 调用 basicAck 确认消息.BasicAckArguments arguments = (BasicAckArguments) basicArguments;ok = virtualHost.basicAck(arguments.getQueueName(), arguments.getMessageId());} else {// 当前的 type 是非法的.throw new MqException("[BrokerServer] 未知的 type! type=" + request.getType());}// 3. 构造响应BasicReturns basicReturns = new BasicReturns();basicReturns.setChannelId(basicArguments.getChannelId());basicReturns.setRid(basicArguments.getRid());basicReturns.setOk(ok);byte[] payload = BinaryTool.toBytes(basicReturns);Response response = new Response();response.setType(request.getType());response.setLength(payload.length);response.setPayload(payload);System.out.println("[Response] rid=" + basicReturns.getRid() + ", channelId=" + basicReturns.getChannelId()+ ", type=" + response.getType() + ", length=" + response.getLength());return response;}private void clearClosedSession(Socket clientSocket) {// 这里主要做的事情就是, 将遍历哈希表, 将不用的session 清楚掉// 不能在集合类中变查询, 边删除List<String> toDeleteChannelId = new ArrayList<>();for (Map.Entry<String ,Socket> entry:sessions.entrySet()) {toDeleteChannelId.add(entry.getKey());}for (String s:toDeleteChannelId) {sessions.remove(s);}}}