# BIO、NIO、AIO ## BIO 传统的IO方式，会在`socket.accept()`方法和`read()`方法发生阻塞。 第一次阻塞等待客户端的连接，第二次阻塞等待客户端的IO操作，这样会导致cpu一直在那等待，造成资源的浪费。 传统的socket通信方式： * client handler ```java package Demo4; import java.io.IOException; import java.io.InputStream; import java.net.Socket; /** * @Author: small_double * @Date: 2019/9/29 下午4:14 * client 处理器 */ public class BioClientHandler implements Runnable { private Socket socket; public BioClientHandler(Socket socket) { this.socket = socket; } @Override public void run() { InputStream inputStream = null; try { inputStream = socket.getInputStream(); byte[] bytes = new byte[1024]; int count = 0; while ((count = inputStream.read(bytes)) != -1) { System.out.println("\n收到服务器端的数据：" + new String(bytes, 0, count, "utf-8")); System.out.print("请输入要发送的消息："); } } catch (IOException e) { e.printStackTrace(); } } } ``` * Bio 客户端 ```java package Demo4; import java.io.IOException; import java.io.OutputStream; import java.net.Socket; import java.util.Scanner; /** * @Author: small_double * @Date: 2019/9/29 下午4:11 * BIO客户端 */ public class BioClient { public static void main(String[] args) { Socket socket = null; OutputStream outputStream = null; try { socket = new Socket("127.0.0.1", 9090); new Thread(new BioClientHandler(socket)).start(); outputStream = socket.getOutputStream(); Scanner scanner = new Scanner(System.in); while (true) { String s = scanner.nextLine(); if (s.trim().equals("bye")) { break; } outputStream.write(s.getBytes()); outputStream.flush(); } } catch (IOException e) { e.printStackTrace(); } finally { try { if (outputStream != null) { outputStream.close(); } if (socket != null) { socket.close(); } } catch (IOException e) { e.printStackTrace(); } } } } ``` * 服务端 ```java package Demo4; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.ServerSocket; import java.net.Socket; import java.util.concurrent.Executor; import java.util.concurrent.Executors; /** * @Author: small_double * @Date: 2019/9/29 下午4:30 */ public class BioServer { public BioServer() { ServerSocket serverSocket = null; try { serverSocket = new ServerSocket(9090); Executor executor = Executors.newFixedThreadPool(10); while (true) { Socket accept = serverSocket.accept(); System.out.println("客户端：" + accept.getRemoteSocketAddress().toString() + "来连接了"); executor.execute(new BioServerHandler(accept)); } } catch (IOException e) { e.printStackTrace(); } finally { if (serverSocket != null) { try { serverSocket.close(); } catch (IOException e) { e.printStackTrace(); } } } } public void start() { } public static void main(String[] args) { new BioServer().start(); } } ``` * bio server handler ```java package Demo4; import demo3.Server; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.ServerSocket; import java.net.Socket; import java.text.SimpleDateFormat; import java.util.Date; /** * @Author: small_double * @Date: 2019/9/29 下午4:37 * bio server handler */ public class BioServerHandler implements Runnable { private Socket serverSocket; public BioServerHandler(Socket serverSocket) { this.serverSocket = serverSocket; } @Override public void run() { InputStream inputStream = null; OutputStream outputStream = null; try { inputStream = serverSocket.getInputStream(); outputStream = serverSocket.getOutputStream(); int count=0; String content=null; byte[] bytes=new byte[1024]; while ((count=inputStream.read(bytes))!=-1){ String line=new String(bytes,0,count,"utf-8"); System.out.println(line); content=line.trim().equalsIgnoreCase("SJ")?new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date()): "你发的啥？"; outputStream.write(content.getBytes()); outputStream.flush(); } } catch (IOException e) { e.printStackTrace(); }finally { if (inputStream != null) { try { inputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (serverSocket != null) { try { serverSocket.close(); } catch (IOException e) { e.printStackTrace(); } } } } } ``` `bio`方式的缺点：浪费cpu资源，同步阻塞方式。 ## NIO nio与bio相比解决了bio两次阻塞的问题（解阻塞） * NIO client ```java package niodemo; 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.SocketChannel; import java.util.Iterator; import java.util.Set; public class NioClient { private SocketChannel socketChannel; private Selector selector; private long timeOut=2000; public NioClient(){ try { socketChannel=SocketChannel.open(); socketChannel.configureBlocking(false); selector=Selector.open(); if(socketChannel.connect(new InetSocketAddress("127.0.0.1",9090))){ socketChannel.register(selector, SelectionKey.OP_READ); }else{ socketChannel.register(selector, SelectionKey.OP_CONNECT); } } catch (IOException e) { e.printStackTrace(); } } public void start(){ try { while (true){ selector.select(timeOut); Set selectionKeys = selector.selectedKeys(); Iterator keyIterator = selectionKeys.iterator(); while (keyIterator.hasNext()){ SelectionKey selectionKey = keyIterator.next(); if(selectionKey.isValid()){ if(selectionKey.isConnectable()){ SocketChannel socketChannel = (SocketChannel) selectionKey.channel(); if(socketChannel.finishConnect()){ socketChannel.register(selector,SelectionKey.OP_READ); ByteBuffer byteBuffer=ByteBuffer.allocate(1024); byteBuffer.put("你好".getBytes()); byteBuffer.flip(); socketChannel.write(byteBuffer); }else{ System.err.println("可以尝试重试"); } } if(selectionKey.isReadable()){ SocketChannel socketChannel = (SocketChannel) selectionKey.channel(); ByteBuffer buffer=ByteBuffer.allocate(1024); socketChannel.read(buffer); System.out.println(new String(buffer.array())); } } keyIterator.remove(); } } } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] args) { new NioClient().start(); } } ``` ## AIO 异步非阻塞 IO --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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