BIO与NIO

其他 2018-10-10 18:56:59 阅读次数: 0

BIO与NIO

1.传统BIO

（1）特点

  1. 面向数据流
  2. 阻塞式传输
  3. 一个客户端对应一个线程
  4. 在客户机增多的情况下，线程资源随之增多，会造成cpu资源枯竭

（2）需求

​ 客户机向服务器输出字符串，逐一在服务器器上打印显示。类似一个简陋的聊天室功能。

（3）代码示例

  1. 服务器程序TimeServer.java

    package com.xm.bio;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class TimeServer {

 public static void main(String[] args) throws IOException {
     int port = 8080;
     if(args != null && args.length>0) {
         try {
             port = Integer.parseInt(args[0]);

         } catch (Exception e) {

         }
     }

     ServerSocket server = null;
     try {
         server = new ServerSocket(port);
         System.out.println("开启服务器:"+server.getLocalSocketAddress());
         Socket socket = null;
         while(true) {
             socket = server.accept();
             new Thread(new TimeServerHandle(socket)).start();
         }
     } finally {
         if(server != null) {
             System.out.println("服务器已关闭！");
             server.close();
             server = null;
         }
     }

 }

}

  2. 服务器处理客户机进程TimeServerHandle.java

    package com.xm.bio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Date;

public class TimeServerHandle implements Runnable {

 private Socket socket;

 public TimeServerHandle(Socket socket) {
     this.socket = socket;
 }

 @Override
 public void run() {
     System.out.println(socket.getInetAddress().toString()+"客户机已连接");
     BufferedReader in = null;
     PrintWriter out = null;
     BufferedReader wt = null;
     try {
         in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
         out = new PrintWriter(socket.getOutputStream(), true);
         wt = new BufferedReader(new InputStreamReader(System.in));
         while(true) {
                 System.out.println(in.readLine());
         }
     } catch (Exception e) {

     } finally {
         if(in != null) {
             try {
                 in.close();
                 in = null;
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
         if(out != null) {
             out.close();
             out = null;
         }
         if(socket != null) {
             try {
                 socket.close();
                 socket = null;
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         }
     }


 }

}

  3. 客户端程序TimeClient.java

    package com.xm.bio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

public class TimeClient {

 public static void main(String[] args) {
     int port = 8080;
     String host = "127.0.0.1";
     Socket socket = null;
     BufferedReader in = null;
     BufferedReader wt = null;
     PrintWriter out = null;
     try {
         socket = new Socket(host, port);
         wt = new BufferedReader(new InputStreamReader(System.in));
         in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
         out = new PrintWriter(socket.getOutputStream(), true);
         String body = null;
         while(true) {
             String str = wt.readLine();
             out.println(str);
         }
     } catch (UnknownHostException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }finally {
         try {
             wt.close();
             in.close();
             out.close();
             socket.close();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }

     }

 }

}

    2.NIO

    （1）NIO特点

    1.面向缓冲区
    2.传输方式为管道传输
    3.非阻塞
    4.支持大并发下的io处理

（2）NIO下的本地文件传输

  1. 内存映射下的缓冲通道

    package com.xm.nio;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.time.Duration;
import java.time.Instant;

import org.junit.jupiter.api.Test;

public class NIOFileDemo {

 /**
  * 1.通过流获取通道
  */
 @Test
 public void test1() {
     Instant begin = Instant.now();
     //1.定义文件流
     FileInputStream fis = null;
     FileOutputStream fos = null;
     //2.获取通道
     FileChannel inChannel = null;
     FileChannel outChannel = null;
     try {
         fis = new FileInputStream("1.jpg");
         fos = new FileOutputStream("2.jpg");

         inChannel = fis.getChannel();
         outChannel = fos.getChannel();

         //3.定义缓冲区
         ByteBuffer buffer = ByteBuffer.allocate(1024);

         //4.读取数据到缓冲区,再从缓冲区写入到文件
         while(inChannel.read(buffer) != -1) {
             //切换到读模式
             buffer.flip();
             //写操作到管道
             outChannel.write(buffer);
             //清空buffer
             buffer.clear();
         }
     } catch (FileNotFoundException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } finally {
         //5.关闭通道和流
         if(inChannel != null) {
             try {
                 inChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(outChannel != null) {
             try {
                 outChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(fis != null) {

             try {
                 fis.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         }
         if(fos != null) {
             try {
                 fos.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         }

         }
     Instant end = begin.plus(Duration.ofSeconds(10));
     System.out.println("Difference in milliseconds : " + Duration.between(begin, end).toMillis());
 }

 /**
  * 通过文件获取管道
  */
 @Test
 public void test2() {
     Instant begin = Instant.now();
     FileChannel inChannel =null;
     FileChannel outChannel = null;
     try {
         inChannel =FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
         /**
          * StandardOpenOption.CREATE与StandardOpenOption.CREATE_NEW的区别
          * 1.StandardOpenOption.CREATE：无则创建，有则覆盖
          * 2.StandardOpenOption.CREATE_NEW：无则创建，有则报错
          */
         outChannel =FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE);
         //3.定义缓冲区
         ByteBuffer buffer = ByteBuffer.allocate(1024);

         //4.读取数据到缓冲区,再从缓冲区写入到文件
         while(inChannel.read(buffer) != -1) {
             //切换到读模式
             buffer.flip();
             //写操作到管道
             outChannel.write(buffer);
             //清空buffer
             buffer.clear();
         }
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } finally {
         //5.关闭通道和流
         if(inChannel != null) {
             try {
                 inChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(outChannel != null) {
             try {
                 outChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }
     Instant end = begin.plus(Duration.ofSeconds(10));
     System.out.println("Difference in milliseconds : " + Duration.between(begin, end).toMillis());

 }

}

  2. 物理映射下的缓冲通道

    package com.xm.nio;

import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.time.Duration;
import java.time.Instant;

import org.junit.Test;

public class NIOFileDemo2 {

 /**
  * 使用直接缓冲区传输
  */
 @Test
 public void test1() {
     Instant begin = Instant.now();
     FileChannel inChannel = null;
     FileChannel outChannel = null;

     try {
         //1.开启通道
         inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
         outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE,StandardOpenOption.READ);

         //2.定义物理缓冲区
         MappedByteBuffer inBuffer = inChannel.map(MapMode.READ_ONLY, 0, inChannel.size());
         MappedByteBuffer outBuffer = outChannel.map(MapMode.READ_WRITE, 0, inChannel.size());

         //3.缓冲区读写操作
         byte[]  dst = new byte[inBuffer.limit()];
         inBuffer.get(dst);
         outBuffer.put(dst);


     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } finally {
         //4.关闭通道
         if(null != inChannel) {

             try {
                 inChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(null != outChannel) {

             try {
                 outChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }
     Instant end = begin.plus(Duration.ofSeconds(10));
     System.out.println("Difference in milliseconds : " + Duration.between(begin, end).toMillis());
 }

 /**
  * 通道之间的传输
  */
 @Test
 public void test2() {
     Instant begin = Instant.now();
     FileChannel inChannel = null;
     FileChannel outChannel = null;
     //获取通道
     try {
         inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
         outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE);

         //通道间传输
         //1.to操作
         //inChannel.transferTo(0, inChannel.size(), outChannel);
         //2.from操作
         outChannel.transferFrom(inChannel, 0, inChannel.size());
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }finally {
         //4.关闭通道
         if(null != inChannel) {

             try {
                 inChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(null != outChannel) {

             try {
                 outChannel.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }
     Instant end = begin.plus(Duration.ofSeconds(10));
     System.out.println("Difference in milliseconds : " + Duration.between(begin, end).toMillis());
 }

}

（3）NIO下的网络传输

  1. 阻塞式

    • 服务端程序

      package com.xm.nio.block;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Scanner;

public class NIOServer {

   public static void main(String[] args) throws IOException {

       int port = 8989;

       //1.获取通道
       ServerSocketChannel serverChannel = ServerSocketChannel.open();

       //2.绑定端口号
       serverChannel.bind(new InetSocketAddress(port));

       //3.获取客户端连接
       SocketChannel socketChannel = serverChannel.accept();

       //定义文件传输通道
       FileChannel outChannel = FileChannel.open(Paths.get("3.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE);
       ByteBuffer buffer = ByteBuffer.allocate(1024);
       while(socketChannel.read(buffer)!=-1) {
           buffer.flip();
           outChannel.write(buffer);
           buffer.clear();
       }

       outChannel.close();
       socketChannel.close();

   }

}

    • 客户端程序

      package com.xm.nio.block;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

public class NIOClient {

   public static void main(String[] args) throws IOException {
       int port = 8989;
       //1.获取通道
       SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", port));


       //2.获取文件通道
       FileChannel inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
       inChannel.transferTo(0, inChannel.size(), socketChannel);

       //3.关闭通道
       inChannel.close();
       socketChannel.close();

   }

}

  2. 非阻塞式

    • 服务端程序

      package com.xm.nio.noblock;

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.ArrayList;
import java.util.Iterator;
import java.util.List;

public class NIOServer {

   public static void main(String[] args) throws IOException {


       int port = 8989;

       //1.开启通道
       ServerSocketChannel serverChannel = ServerSocketChannel.open();

       //2.绑定端口号
       serverChannel.bind(new InetSocketAddress(port));

       //3.设置非阻塞
       serverChannel.configureBlocking(false);

       //4.开启选择器
       Selector selector = Selector.open();

       //5.注册连接监听
       serverChannel.register(selector, SelectionKey.OP_ACCEPT);

       List<SocketChannel> channels = new ArrayList<>();

       while(selector.select() > 0) {
           Iterator<SelectionKey> keys = selector.selectedKeys().iterator();

           while(keys.hasNext()) {
               SelectionKey key = keys.next();
               if(key.isAcceptable()) {
                   SocketChannel socketChannel = serverChannel.accept();
                   channels.add(socketChannel);
                   System.out.println("客户端连接成功："+socketChannel.getLocalAddress()+" hashcode:"+socketChannel.hashCode());
                   socketChannel.configureBlocking(false);
                   socketChannel.register(selector, SelectionKey.OP_READ);
               } else if(key.isReadable()) {
                   SocketChannel socketChannel = (SocketChannel) key.channel();
                   ByteBuffer dst = ByteBuffer.allocate(1024);
                   int len;
                   while(-1 != (len=socketChannel.read(dst))) {
                       dst.flip();
                       System.out.println(new String(dst.array(),0,len));
                       /*for(SocketChannel sChannel:channels) {
                           if(sChannel != socketChannel) {
                               dst.flip();
                               sChannel.write(dst);
                           }
                       }*/
                       dst.clear();
                   }
               }       
           }

           keys.remove();
       }

   }

}

    • 客户端

      package com.xm.nio.noblock;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Iterator;
import java.util.Scanner;

public class NIOClient{

   SocketChannel socketChannel;


   public NIOClient() throws IOException {
       int port = 8989;
       //1.获取通道
       socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", port));
       //2.设置异步非阻塞
       socketChannel.configureBlocking(false);

       //2.获取文件通道
       FileChannel inChannel = FileChannel.open(Paths.get("1.md"), StandardOpenOption.READ);
       inChannel.transferTo(0, inChannel.size(), socketChannel);

               //3.关闭通道
               inChannel.close();
               socketChannel.close();

   }


   public static void main(String[] args)  {   
       try {
           new NIOClient();
       } catch (IOException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }

   }



}

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