Socket

Java中的网络编程，指的就是Socket

传统IO服务写法：

【客户端】

package com.zy.socket;

import java.io.IOException;
import java.net.Socket;
import java.util.Date;

public class SocketClient {
    public static void main(String[] args) {
        new Thread(() -> {
            try {
                Socket socket = new Socket("127.0.0.1", 9231);
                while (true) {
                    try {
                        socket.getOutputStream().write((new Date() + ": hello world").getBytes());
                        socket.getOutputStream().flush();
                        Thread.sleep(2000);
                    } catch (Exception e) {
                        
                    }
                }
            } catch (IOException e) {
            }
        }).start();
    }
}

【服务端】

package com.zy.socket;

import java.io.IOException;
import java.net.Socket;
import java.util.Date;

public class SocketClient {
    public static void main(String[] args) {
        new Thread(() -> {
            try {
                Socket socket = new Socket("127.0.0.1", 9231);
                while (true) {
                    try {
                        socket.getOutputStream().write((new Date() + ": hello world").getBytes());
                        socket.getOutputStream().flush();
                        Thread.sleep(2000);
                    } catch (Exception e) {
                        
                    }
                }
            } catch (IOException e) {
            }
        }).start();
    }
}

但是上面的写法存在问题，即没来一个新的socket连接，系统就必须开启一个新的线程去处理，久而久之，当高并发时，系统会吃不消

下面是才用线程池的改良版

【服务端】

package com.zy.socket;

import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class SocketServerPool {
    public static void main(String[] args) throws Exception {

        ServerSocket serverSocket = new ServerSocket(9231);
        ExecutorService pool = Executors.newFixedThreadPool(5);
        new Thread(() -> {
            while(true) {
                try {
                    
                    // accept是阻塞的，只有当当前socket接收到信息时，才会往下执行
                    Socket socket = serverSocket.accept();
                    pool.submit(new MySocketTask(socket));
                    
                } catch (Exception e) {
                    // TODO: handle exception
                }
            }
        }).start();
    
    }
}


class MySocketTask implements Runnable {
    private Socket socket;

    public MySocketTask(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        System.out.println("正在执行socket:"+Thread.currentThread().getName());
        try {
            byte[] data = new byte[1024];
            InputStream inputStream = socket.getInputStream();
            while(true) {
                int len;
                
                while((len = inputStream.read(data)) != -1) {
                    System.out.println(new String(data, 0, len));
                }
            }
        } catch (Exception e) {
            // TODO: handle exception
        }
        System.out.println("socket 执行完毕");
    }
}