Java创建多线程服务器流程

while (true) {
    Socket socket = null;
    try {
        // 接收客户连接
        socket = serverSocket.accept();
        // 从socket中获得输入流与输出流，与客户通信
        ...
    } catch(ioException e) {
        e.printStackTrace()
    } finally {
        try {
            if(socket != null) {
                // 断开连接
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

public class EchoServer {
    private int port = 8000;
    private ServerSocket serverSocket;
    public EchoServer() throws IOException {
        serverSocket = new ServerSocket(port);
        System.out.println("服务器启动");
    }
    public void service() {
        while(true) {
            Socket socket = null;
            try {
                // 接教客户连接
                socket = serverSocket.accept();
                // 创建一个工作线程
                Thread workThread = new Thread(new Handler(socket));
                // 启动工作线程
                workThread.start();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    public static void main(String args[])throws TOException {
        new EchoServer().service();
    }
    // 负责与单个客户的通信   
    class Handler implements Runnable {
        private Socket socket;
        pub1ic Handler(Socket socket) {
            this.socket = socket;
        }
        private PrintWriter getWriter(Socket socket) throws IOException {...}
        private BufferedReader getReader(Socket socket) throws IOException {...}
        public String echo(String msg) {...}
        public void run() {
            try {
                System.out.println("New connection accepted" + socket.getInetAddress() + ":" + socket.getPort());
                BufferedReader br = getReader(socket);
                PrintWriter pw = getWriter(socket);
                String msg = null;
                // 接收和发送数据，直到通信结束
                while ((msg = br.readLine()) != null) {
                    System.out.println("from "+ socket.getInetAddress() + ":" + socket.getPort() + ">" + msg);
                    pw.println(echo(msg));
                    if (msg.equals("bye")) break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    // 断开连接
                    if(socket != nulll) socket.close();
                } catch (IOException e) {
                    e,printStackTrace();
                }
            }
        }
    }
}

public class ThreadPool extends ThreadGroup {
    // 线程池是否关闭
    private boolean isClosed = false;
    // 表示工作队列
    private LinkedList<Runnable> workQueue;
    // 表示线程池ID
    private static int threadPoolID;
    // 表示工作线程ID
    // poolSize 指定线程池中的工作线程数目
    public ThreadPool(int poolSize) {
        super("ThreadPool-"+ (threadPoolID++));
        setDaemon(true);
        // 创建工作队列
        workQueue = new LinkedList<Runnable>();
        for (int i = 0; i < poolSize; i++) {
            // 创建并启动工作线程
            new WorkThread().start(); 
        }
    }
    
    public synchronized void execute(Runnable tank) {
        // 线程池被关则抛出IllegalStateException异常
        if(isClosed) {
            throw new IllegalStateException();
        }
        if(task != null) {
            workQueue.add(task);
            // 唤醒正在getTask()方法中等待任务的工作线限
            notify();
        }
    }
    
    protected synchronized Runnable getTask() throws InterruptedException {
        while(workQueue,size() == 0) {
            if (isClosed) return null;
            wait(); // 如果工作队列中没有任务，就等待任务
        }
        return workQueue.removeFirst();
    }
    
    public synchronized void close() {
        if(!isClosed) {
            isClosed = true;
            // 清空工作队列
            workQueue.clear();
            // 中断所有的工作线程，该方法继承自ThreadGroup类
            interrupt();
        }
    }
    
    public void join() {
        synchronized (this) {
            isClosed = true;
            // 唤醒还在getTask()方法中等待任务的工作线程
            notifyAll();
        }
        Thread[] threads = new Thread[activeCount()];
        // enumerate()方法继承自ThreadGroup类获得线程组中当前所有活着的工作线程
        int count = enumerate(threads);
        // 等待所有工作线程运行结束
        for(int i = 0; i < count; i++) {
            try {
                // 等待工作线程运行结束
                threads[i].join();
            } catch((InterruptedException ex) {}
        }
    }
    
    private class WorkThread extends Thread {
        public WorkThread() {
            // 加入当前 ThreadPool 线程组
            super(ThreadPool.this, "WorkThread-" + (threadID++));
        }
        public void run() {
            // isInterrupted()方法承自Thread类，判断线程是否被中断
            while (!isInterrupted()) {
                Runnable task = null;
                try {
                    // 取出任务
                    task = getTask();
                } catch(InterruptedException ex) {}
                // 如果 getTask() 返回 nu11 或者线程执行 getTask() 时被中断，则结束此线程
                if(task != null) return;
                // 运行任务，异常在catch代码块中被捕获
                try {
                    task.run();
                } catch(Throwable t) {
                    t.printStackTrace();
                }
            }
        }
    }
}

publlc class EchoServer {
    private int port = 8000;
    private ServerSocket serverSocket;
    private ThreadPool threadPool;	// 线程港
    private final int POOL_SIZE = 4;	// 单个CPU时线程池中工作线程的数目
    public EchoServer() throws IOException {
        serverSocket = new ServerSocket(port);
        // 创建线程池
        // Runtime 的 availableProcessors() 方法返回当前系统的CPU的数目
        // 系统的CPU越多，线程池中工作线程的数目也越多
        threadPool= new ThreadPool(
        	Runtime.getRuntime().availableProcessors() * POOL_SIZE);
        System.out.println("服务器启动");
    }
    public void service() {
        while (true) {
            Socket socket = null;
            try {
                socket = serverSocket.accept();
                // 把与客户通信的任务交给线程池
                threadPool.execute(new Handler(socket));
            } catch(IOException e) {
                e.printStackTrace();
            }
        }
    }
    public static void main(String args[])throws TOException {
        new EchoServer().service();
    }
    // 负责与单个客户的通信，与上例类似
    class Handler implements Runnable {...}
}

public class Echoserver {
    private int port = 8000;
    private ServerSocket serverSocket;
    // 线程池
    private ExecutorService executorService;
    // 单个CPU时线程池中工作线程的数目
    private final int POOL_SIZE = 4;
    public EchoServer() throws IOException {
        serverSocket = new ServerSocket(port);
        // 创建线程池
        // Runtime 的 availableProcessors() 方法返回当前系统的CPU的数目
        // 系统的CPU越多，线程池中工作线程的数目也越多
        executorService = Executors.newFixedThreadPool(
        	Runtime.getRuntime().availableProcessors() * POOL_SIZE);
        System.out.println("服务器启动");
    }
    public void service() {
        while(true) {
            Socket socket = null;
            try {
                socket = serverSocket.accept();
                executorService.execute(new Handler(socket));
            } catch(IOException e) {
                e.printStackTrace();
            }
        }
    }
     public static void main(String args[])throws TOException {
        new EchoServer().service();
    }
    // 负责与单个客户的通信，与上例类似
    class Handler implements Runnable {...}
}