消息队列(12) - 定义服务器类
目录
- 前言
- 设计思想
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 socket
clientSocket.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 channel
sessions.put(basicArguments.getChannelId(), clientSocket);
System.out.println("[BrokerServer] 创建 channel 完成! channelId=" + basicArguments.getChannelId());
} else if (request.getType() == 0x2) {
// 销毁 channel
sessions.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
@Override
public 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 SubScribeReturns
response.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);
}
}
}