第二章 BIO与NIO

 1 package bio;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.IOException;
 5 import java.io.InputStreamReader;
 6 import java.io.PrintWriter;
 7 import java.net.ServerSocket;
 8 import java.net.Socket;
 9 import java.util.Date;
10 
11 public class BioServer {
12 
13     public static void main(String[] args) throws IOException {
14         ServerSocket serverSocket = new ServerSocket(8081);
15         Socket clientSocket = null;
16         while(true){
17             clientSocket = serverSocket.accept();//如果没有客户端接入,主线程阻塞在这里
18             new Thread(new ServerHandler(clientSocket)).start();
19         }
20         //finall关闭serverSocket
21     }
22 
23 }
24 
25 class ServerHandler implements Runnable{
26     private Socket clientSocket;
27 
28     public ServerHandler(Socket clientSocket) {
29         this.clientSocket = clientSocket;
30     }
31 
32     @Override
33     public void run() {
34         try {
35             BufferedReader reader = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
36             PrintWriter writer = new PrintWriter(this.clientSocket.getOutputStream(), true);
37             while(true){
38                 String body = reader.readLine();
39                 if (body==null){
40                     break;
41                 }
42                 System.out.println(body);
43                 writer.println(new Date().toString() + "->" + body);
44             }
45         } catch (IOException e) {
46             e.printStackTrace();
47         }
48         //finally关闭资源:流和socket
49     }
50 }

 1 package bio;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.IOException;
 5 import java.io.InputStreamReader;
 6 import java.io.PrintWriter;
 7 import java.net.Socket;
 8 
 9 public class BioClient {
10     public static void main(String[] args) throws IOException {
11         Socket clientSocket = new Socket("127.0.0.1", 8081);
12         BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
13         PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);
14         writer.println("haha");
15         String resp = reader.readLine();
16         System.out.println(resp);
17         //finall关闭serverSocket
18     }
19 }

 1 package nio;
 2 
 3 import java.io.IOException;
 4 import java.net.InetSocketAddress;
 5 import java.nio.ByteBuffer;
 6 import java.nio.channels.SelectionKey;
 7 import java.nio.channels.Selector;
 8 import java.nio.channels.ServerSocketChannel;
 9 import java.nio.channels.SocketChannel;
10 import java.util.Iterator;
11 
12 public class NioServer {
13     public static void main(String[] args) throws IOException {
14         Selector selector = Selector.open();
15 
16         ServerSocketChannel serverChannel = ServerSocketChannel.open();
17         serverChannel.configureBlocking(false);
18         serverChannel.socket().bind(new InetSocketAddress(8083));//监听链接8082端口的客户端socket
19         serverChannel.register(selector, SelectionKey.OP_ACCEPT);//将serverChannel注册到selector,并监听接受连接事件
20 
21         while (selector.select() > 0) {//该方法会发生阻塞,直到至少有一个事件"准备就绪"为止
22             Iterator<SelectionKey> it = selector.selectedKeys().iterator();
23             while (it.hasNext()) {
24                 SelectionKey sk = it.next();
25                 if (sk.isAcceptable()) {
26                     SocketChannel clientChannel = serverChannel.accept();//相当于客户端三次握手
27                     clientChannel.configureBlocking(false);
28                     clientChannel.register(selector, SelectionKey.OP_READ);
29                 } else if (sk.isReadable()) {
30                     SocketChannel clientChannel = (SocketChannel) sk.channel();
31                     ByteBuffer buf = ByteBuffer.allocate(1024);
32                     while (clientChannel.read(buf) > 0) {//将通道中的数据读到缓冲区,因为clientChannel已经是非阻塞的,所以这里的read是非阻塞的
33                         buf.flip();//将缓冲区由写模式切换到读模式
34                         byte[] bytes = new byte[buf.remaining()];
35                         buf.get(bytes);//将缓冲区中的数据读取到bytes中
36                         String body = new String(bytes, "UTF-8");
37                         System.out.println("接收到来自客户端的信息:" + body);
38                         buf.clear();
39                     }
40                 }
41                 it.remove();
42             }
43         }
44     }
45 }

 1 package nio;
 2 
 3 import java.io.IOException;
 4 import java.net.InetSocketAddress;
 5 import java.nio.ByteBuffer;
 6 import java.nio.channels.SocketChannel;
 7 
 8 public class NioClient {
 9     public static void main(String[] args) throws IOException {
10         SocketChannel clientChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8083));//向服务端发出连接请求,服务端会通过accept()方法实现三次握手后,建立连接
11         clientChannel.configureBlocking(false);
12         ByteBuffer buf = ByteBuffer.allocate(1024);//分配在JVM堆中:capacity=1024;position=0;limit=1024
13 //        ByteBuffer buf = ByteBuffer.allocateDirect(1024);//分配在堆外内存(物理内存)中
14         buf.put("abcde".getBytes());//将数据写入缓冲区buf中:capacity=1024;position=5;limit=1024
15         buf.flip();//将缓冲区从写模式切换到读模式:capacity=1024;position=0;limit=5
16         clientChannel.write(buf);//将缓冲区的数据写入通道:capacity=1024;position=5;limit=5
17         buf.clear();//清空缓冲区:capacity=1024;position=0;limit=1024
18         clientChannel.close();
19     }
20 }