基于NIO实现Discard服务器

基于NIO实现Discard服务器

1.服务端DisCardServer

package com.netty.redis.zookeeper.netty.unit1.oneday;

import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;

/**
 * @Description: 基于NIO实现Discard服务器
 * @ClassName: DisCardServer
 * @Author zhaomx
 * @Version 1.0
 * @Date 2021-07-13 10:41
 */
@Slf4j
public class DisCardServer {

    public static void main(String[] args) throws IOException {
        // 1.获取Selector选择器，Selector是实现nio多路复用的核心
        Selector selector = Selector.open();
        // 2.打开套接字通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        // 3.设置为非阻塞
        serverSocketChannel.configureBlocking(false);
        // 4.绑定连接
        serverSocketChannel.bind(new InetSocketAddress("127.0.0.1", 7777));
        // 5.将通道注册到选择器上,并注册的IO事件为：读就绪
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        // 6.轮询已就绪的I/O就绪事件（选择键集合）
        while (selector.select() > 0) {
            // 7.获取选择键集合
            Iterator<SelectionKey> selectedKeys = selector.selectedKeys().iterator();
            while (selectedKeys.hasNext()) {
                // 8.获取单个的选择键，并处理
                SelectionKey selectedKey = selectedKeys.next();
                // 9.判断key是具体的什么事件，不同的事件类型，做不同的处理
                if (selectedKey.isAcceptable()) {
                    // 若选择键的IO事件是 连接就绪 事件,就获取客户端连接，此时新的客户端请求连接，需要获取链接通道，并将通道绑定到选择器上。
                    SocketChannel socketChannel = serverSocketChannel.accept();
                    // 切换为非阻塞模式
                    socketChannel.configureBlocking(false);
                    // 将该通道注册到selector选择器上
                    socketChannel.register(selector, SelectionKey.OP_READ);
                } else if (selectedKey.isReadable()) {
                    // 10-1.若选择键的IO事件是“可读”事件,读取数据
                    SocketChannel socketChannel = (SocketChannel) selectedKey.channel();
                    // 10-2.读取数据
                    ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                    //10-3.把读取的数据写入到输出通道中，相当于从缓冲区中读取数据，将writeBuffer从写模式变为读模式
                    int length = 0;
                    while ((length = socketChannel.read(byteBuffer)) > 0) {
                        byteBuffer.flip();
                        log.info(new String(byteBuffer.array(), 0, length));
                        byteBuffer.clear();
                    }
                    socketChannel.close();
                }
                // 11.清除选择键
                selectedKeys.remove();
            }
        }
        // 12.关闭连接
        serverSocketChannel.close();
    }
}

2.客户端DisCardClient

package com.netty.redis.zookeeper.netty.unit1.oneday;

import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Scanner;

/**
 * @Description: DisCardClient客户端
 * @ClassName: DisCardClient
 * @Author zhaomx
 * @Version 1.0
 * @Date 2021-07-13 11:01
 */
@Slf4j
public class DisCardClient {

    public static void main(String[] args) throws IOException {
        // 1.打开套接字通道SocketChannel
        SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 7777));
        // 2.切换成非阻塞模式
        socketChannel.configureBlocking(false);
        //3.不断的自旋、等待连接完成，或者做一些其他的事情
        while (!socketChannel.finishConnect()) {

        }
        // 4、分配指定大小的缓冲区
        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
        byteBuffer.put("hello world this is discard client ".getBytes("UTF-8"));
        byteBuffer.flip();
        socketChannel.write(byteBuffer);
        byteBuffer.clear();
        //关闭通道
        socketChannel.shutdownOutput();
        socketChannel.close();
    }
}

借鉴：https://blog.youkuaiyun.com/u010105645/article/details/106201658