BIO與NIO

時間  2021-01-08
標籤 java api 服務器 網絡 併發 app 異步 socket ide this 欄目 Netty 简体版
原文   原文鏈接

BIO與NIO

1.傳統BIO

（1）特色

  1. 面向數據流
  2. 阻塞式傳輸
  3. 一個客戶端對應一個線程
  4. 在客戶機增多的狀況下，線程資源隨之增多，會形成cpu資源枯竭

（2）需求

​ 客戶機向服務器輸出字符串，逐一在服務器器上打印顯示。相似一個簡陋的聊天室功能。java

（3）代碼示例

  1. 服務器程序TimeServer.javaapi

    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("開啓服務器:"+server.getLocalSocketAddress());
			Socket socket = null;
			while(true) {
				socket = server.accept();
				new Thread(new TimeServerHandle(socket)).start();
			}
		} finally {
			if(server != null) {
				System.out.println("服務器已關閉！");
				server.close();
				server = null;
			}
		}

	}

}

  2. 服務器處理客戶機進程TimeServerHandle.java服務器

    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()+"客戶機已鏈接");
		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. 客戶端程序TimeClient.java網絡

    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特色

1.面向緩衝區 2.傳輸方式爲管道傳輸 3.非阻塞 4.支持大併發下的io處理併發

（2）NIO下的本地文件傳輸

  1. 內存映射下的緩衝通道app

    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.經過流獲取通道
	 */
	@Test
	public void test1() {
		Instant begin = Instant.now();
		//1.定義文件流
		FileInputStream fis = null;
		FileOutputStream fos = null;
		//2.獲取通道
		FileChannel inChannel = null;
		FileChannel outChannel = null;
		try {
			fis = new FileInputStream("1.jpg");
			fos = new FileOutputStream("2.jpg");

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

			//3.定義緩衝區
			ByteBuffer buffer = ByteBuffer.allocate(1024);

			//4.讀取數據到緩衝區,再從緩衝區寫入到文件
			while(inChannel.read(buffer) != -1) {
				//切換到讀模式
				buffer.flip();
				//寫操做到管道
				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.關閉通道和流
			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());
	}

	/**
	 * 經過文件獲取管道
	 */
	@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與StandardOpenOption.CREATE_NEW的區別
			 * 1.StandardOpenOption.CREATE：無則建立，有則覆蓋
			 * 2.StandardOpenOption.CREATE_NEW：無則建立，有則報錯
			 */
			outChannel =FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE);
			//3.定義緩衝區
			ByteBuffer buffer = ByteBuffer.allocate(1024);

			//4.讀取數據到緩衝區,再從緩衝區寫入到文件
			while(inChannel.read(buffer) != -1) {
				//切換到讀模式
				buffer.flip();
				//寫操做到管道
				outChannel.write(buffer);
				//清空buffer
				buffer.clear();
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			//5.關閉通道和流
			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. 物理映射下的緩衝通道異步

    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 {

	/**
	 * 使用直接緩衝區傳輸
	 */
	@Test
	public void test1() {
		Instant begin = Instant.now();
		FileChannel inChannel = null;
		FileChannel outChannel = null;

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

			//2.定義物理緩衝區
			MappedByteBuffer inBuffer = inChannel.map(MapMode.READ_ONLY, 0, inChannel.size());
			MappedByteBuffer outBuffer = outChannel.map(MapMode.READ_WRITE, 0, inChannel.size());

			//3.緩衝區讀寫操做
			byte[]  dst = new byte[inBuffer.limit()];
			inBuffer.get(dst);
			outBuffer.put(dst);


		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			//4.關閉通道
			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());
	}

	/**
	 * 通道之間的傳輸
	 */
	@Test
	public void test2() {
		Instant begin = Instant.now();
		FileChannel inChannel = null;
		FileChannel outChannel = null;
		//獲取通道
		try {
			inChannel = FileChannel.open(Paths.get("1.jpg"), StandardOpenOption.READ);
			outChannel = FileChannel.open(Paths.get("2.jpg"), StandardOpenOption.WRITE,StandardOpenOption.CREATE);

			//通道間傳輸
			//1.to操做
			//inChannel.transferTo(0, inChannel.size(), outChannel);
			//2.from操做
			outChannel.transferFrom(inChannel, 0, inChannel.size());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//4.關閉通道
			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下的網絡傳輸

  1. 阻塞式socket

    • 服務端程序ide

      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.獲取通道
		ServerSocketChannel serverChannel = ServerSocketChannel.open();

		//2.綁定端口號
		serverChannel.bind(new InetSocketAddress(port));

		//3.獲取客戶端鏈接
		SocketChannel socketChannel = serverChannel.accept();

		//定義文件傳輸通道
		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();

	}

}

    • 客戶端程序this

      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.獲取通道
		SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", port));


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

		//3.關閉通道
		inChannel.close();
		socketChannel.close();

	}

}

  2. 非阻塞式

    • 服務端程序

      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.開啓通道
		ServerSocketChannel serverChannel = ServerSocketChannel.open();

		//2.綁定端口號
		serverChannel.bind(new InetSocketAddress(port));

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

		//4.開啓選擇器
		Selector selector = Selector.open();

		//5.註冊鏈接監聽
		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("客戶端鏈接成功："+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();
		}

	}

}

    • 客戶端

      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.獲取通道
		socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", port));
		//2.設置異步非阻塞
		socketChannel.configureBlocking(false);

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

				//3.關閉通道
				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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