3.Netty之一个基于NIO的服务端

悠悠 2022-05-28 13:57 195阅读 0赞

看了一下《Java NIO》这本书，然后尝试着写了一个服务端demo

package com.bj58.pn.nio;
    
    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;
    
    public class NonIOServer implements Runnable {
    	Selector selector;
    
    	public NonIOServer(int port) throws IOException {
    		// 0.开启selector监听器
    		selector = Selector.open();
    		// 1.开启通道
    		ServerSocketChannel ssc = ServerSocketChannel.open();
    		// 2.通道监听端口
    		ssc.bind(new InetSocketAddress(port));
    		// 3.设置通道属性(非阻塞)
    		ssc.configureBlocking(Boolean.FALSE);
    		// 4.注册到selector选择器
    		ssc.register(selector, SelectionKey.OP_ACCEPT);
    	}
    
    	@Override
    	public void run() {
    		while (true) {
    			try {
    				// 1.开始监听
    				selector.select();
    				// 2.获取多路复用器选择的结果集
    				Iterator<SelectionKey> it = selector.selectedKeys().iterator();
    				while (it.hasNext()) {
    					SelectionKey key = it.next();
    					it.remove();
    					if (key.isValid() && key.isAcceptable()) {
    						doAccept(key);
    					}
    					if (key.isValid() && key.isReadable()) {
    						doRead(key);
    					}
    					if (key.isValid() && key.isWritable()) {
    						doWrite(key);
    					}
    				}
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    
    	private void doAccept(SelectionKey key) {
    		try {
    			SocketChannel sc = ((ServerSocketChannel) key.channel()).accept();
    			sc.configureBlocking(Boolean.FALSE);
    			sc.register(selector, SelectionKey.OP_READ);
    		} catch (IOException e) {
    			System.out.println("accept 异常");
    			e.printStackTrace();
    		}
    
    	}
    
    	private void doRead(SelectionKey key) {
    		SocketChannel sc = (SocketChannel) key.channel();
    		ByteBuffer reqBuffer = ByteBuffer.allocate(2048);
    
    		try {
    			int i = sc.read(reqBuffer);
    			if (i >= 0) {
    				reqBuffer.flip();
    				byte[] bytes = new byte[reqBuffer.remaining()];
    				reqBuffer.get(bytes);
    				System.out.println(new String(bytes));
    				key.attach("res");
    				key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
    			} else {
    				sc.close();
    			}
    		} catch (IOException e) {
    			System.out.println("read 异常");
    			try {
    				sc.close();
    				sc.socket().close();
    			} catch (IOException e1) {
    				e1.printStackTrace();
    			}
    		}
    	}
    
    	private void doWrite(SelectionKey key) {
    		SocketChannel sc = (SocketChannel) key.channel();
    		String handle = (String) key.attachment();// 取出read方法传递的信息。
    		ByteBuffer retBuffer = ByteBuffer.wrap(handle.getBytes());
    
    		try {
    			sc.write(retBuffer);
    			sc.close();
    		} catch (IOException e) {
    			System.out.println("write 异常");
    			e.printStackTrace();
    		}
    	}
    
    	public static void main(String[] args) throws IOException {
    		System.out.println("正在启动服务...");
    		new Thread(new NonIOServer(8000)).start();
    	}
    
    }