java NIO实现

系统管理员 2024-04-17 21:13 49阅读 0赞

NIO工作流程如图  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMjIyNjgw_size_16_color_FFFFFF_t_70]

package 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.nio.charset.Charset;  
import java.nio.charset.CharsetDecoder;  
import java.util.Iterator;  
import java.util.Set;  
import java.util.concurrent.ExecutorService;  
import java.util.concurrent.Executors;

public class Service \{

private static Charset charset=Charset.forName("UTF-8");
    
    private static CharsetDecoder decoder=charset.newDecoder();
    
    public static void main(String[] args) throws IOException {
    	//1：创建一个注册中心
    	Selector selector=Selector.open();
    	//2创建通道
    	ServerSocketChannel channel=ServerSocketChannel.open();
    	int port=9200;
    	//3把通道绑定到服务端口
    	channel.bind(new InetSocketAddress(port));
    	//4：把通道注册到selector 非阻塞
    	channel.configureBlocking(false);
    	channel.register(selector, SelectionKey.OP_ACCEPT);
    	 int connectionCount=0;
    	 ExecutorService executorService=Executors.newFixedThreadPool(3);
    	 while(true){
    		 //得到就绪的channel的数量
    		int readChannelCount=selector.select(); 
    		if(readChannelCount==0){
    			continue;	
    		}
    		//得到就绪的channel的key
    		Set<SelectionKey> selectedKeys=selector.selectedKeys();
    		Iterator<SelectionKey> keyIterator=selectedKeys.iterator();
    		while(keyIterator.hasNext()){
    			SelectionKey key=keyIterator.next();
    			//可接收的通道
    			if(key.isAcceptable()){
    				ServerSocketChannel channel2=(ServerSocketChannel) key.channel();
    				SocketChannel socketChannel=channel2.accept();
    				socketChannel.configureBlocking(false);
    				socketChannel.register(selector, SelectionKey.OP_READ, ++connectionCount);
    			}else if(key.isReadable()){
    				//交给线程处理读取数据
    				executorService.execute(new SocketProcess(key));
    				key.cancel();
    			}
    			keyIterator.remove();
    		}
    	 }
    	
    }
    
    static class SocketProcess implements Runnable{
    	SelectionKey key;
    	private SocketProcess(SelectionKey key){
    		super();
    		this.key=key;
    	}
    	
    	@Override
    	public void run() {
    		try{
    			System.out.println("连接："+key.attachment()+"发来了："+readFormChannel());
    		}catch(Exception e){
    			e.printStackTrace();
    		}
    	}
    	
    	private String readFormChannel() throws IOException{
    		SocketChannel channel=(SocketChannel) key.channel();
    		int size=1024;
    		ByteBuffer buffer=ByteBuffer.allocateDirect(size);
    		//定义一个更大的buffer
    		ByteBuffer bigBuffer=null;
    		int count=0;
    		while((channel.read(buffer))!=-1){
    			count++;
    			ByteBuffer temp=ByteBuffer.allocateDirect(size*(count+1));
    			if(bigBuffer!=null){
    				bigBuffer.flip();
    				temp.put(bigBuffer);
    			}
    			bigBuffer=temp;
    			buffer.flip();
    			bigBuffer.put(buffer);
    			buffer.clear();
    			if(bigBuffer!=null){
    				bigBuffer.flip();
    				try{
    					return decoder.decode(bigBuffer).toString();
    				}catch(Exception e){
    					e.printStackTrace();
    				}
    			}
    		}
    		return null;
    	}
    }

package nio;

import java.net.InetSocketAddress;  
import java.nio.ByteBuffer;  
import java.nio.channels.SocketChannel;  
import java.nio.charset.Charset;  
import java.util.Scanner;

public class Client \{

private static Charset charset=Charset.forName("UTF-8");
    
    public static void main(String[] args) {
    	
    	try{
    		SocketChannel channel=SocketChannel.open();
    		boolean connection=channel.connect(new InetSocketAddress("localhost", 9200));
    		System.out.println(connection);
    		Scanner scanner=new Scanner(System.in);
    		System.out.println("请输入：");
    		String message=scanner.nextLine();
    		ByteBuffer buffer=ByteBuffer.wrap(message.getBytes(charset));
    		while(buffer.hasRemaining()){
    			int writedCount=channel.write(buffer);
    		}
    	}catch(Exception e){
    		e.printStackTrace();
    	}
    	
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyMjIyNjgw_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/03b8872c25704688bdb75d58c95a395c.png