【从NIO到Netty】1.BIO存在的问题

package org.scaventz.bio;

import io.netty.util.CharsetUtil;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.*;

public class BioEchoServer {

    private ServerSocket serverSocket;
    private final int PORT = 8080;

    private ExecutorService exec = new ThreadPoolExecutor(10, 20, 5, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(50));

    public void init() throws IOException {
        serverSocket = new ServerSocket();
        serverSocket.bind(new InetSocketAddress(PORT));
    }

    public void startup() throws IOException {

        while (true) {
            System.out.println("等待连接");
            Socket socket = serverSocket.accept();
            System.out.println("与 " + socket.getInetAddress() + " 建立连接");
            exec.execute(new Thread(() -> {
                InputStream inputStream = null;
                OutputStream outputStream = null;
                try {
                    inputStream = socket.getInputStream();
                    outputStream = socket.getOutputStream();
                    TimeUnit.SECONDS.sleep(2);
                    byte[] bytes = new byte[inputStream.available()];
                    inputStream.read(bytes);
                    System.out.println("[客户端-" + socket.getRemoteSocketAddress() + "]: " + new String(bytes, CharsetUtil.UTF_8));
                    outputStream.write(bytes);
                } catch (InterruptedException | IOException e) {
                    e.printStackTrace();
                } finally {
                    try {
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }));
        }
    }

    public static void main(String[] args) throws IOException {
        BioEchoServer server = new BioEchoServer();
        server.init();
        server.startup();
    }
}

上面是一段BIO模式的Server端代码

这段代码存在的性能问题：

1. 红色部分，线程会被阻塞
2. 每个连接，都分配给一个单独的线程进行处理

下一节【从BIO到Netty】2.NIO 概述我们来看看 NIO 解决这些问题的思路