java进阶-Netty

Netty

在此非常感谢尚硅谷学院以及韩顺平老师在B站公开课

Netty视频教程

Netty demo代码文件

I/O

说NIO之前先说一下BIO（Blocking IO）,如何理解这个Blocking呢？客户端监听（Listen）时，Accept是阻塞的，只有新连接来了，Accept才会返回，主线程才能继读写socket时，Read是阻塞的，只有请求消息来了，Read才能返回，子线程才能继续处理读写socket时，Write是阻塞的，只有客户端把消息收了，Write才能返回，子线程才能继续读取下一个请求

BIO

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适用连接数目少且固定的服务

package com.example.demo01.netty;import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class BIODemo01 {public static void main(String[] args) throws IOException {ExecutorService executorService = Executors.newCachedThreadPool();ServerSocket serverSocket = new ServerSocket(8080);System.out.println("服务器启动成功。。。");while(true){try {System.out.println(Thread.currentThread().getName() + " 等待连接正在阻塞。。。。。。");final Socket socket = serverSocket.accept();executorService.submit(() -> {socketHandler(socket);});} catch (IOException e) {throw new RuntimeException(e);}}}private static void socketHandler(Socket socket) {try {InputStream inputStream = socket.getInputStream();byte[] bytes = new byte[1024];while (true){System.out.println(Thread.currentThread().getName() + " 读取数据正在阻塞。。。");int read = inputStream.read(bytes);if(read != -1){System.out.println(new String(bytes, 0, read));}}} catch (IOException e) {throw new RuntimeException(e);}}
}

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NIO

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适用连接数目多且连接比较短的服务
jdk1.4开始支持

AIO

适用连接数目多且连接比较长的服务
jdk7开始支持

NIO原理

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FIleBuffer

package com.example.demo01.netty.nio;import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;public class NioFileChannel {public static void main(String[] args) throws Exception {String str = new String("测试文档");ByteBuffer allocate = ByteBuffer.allocate(1024);allocate.put(str.getBytes());allocate.flip();FileOutputStream fileOutputStream = new FileOutputStream("d:\\test.txt");FileChannel channel = fileOutputStream.getChannel();channel.write(allocate);fileOutputStream.close();}
}

package com.example.demo01.netty.nio;import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;public class NioFileChannelInputStream {public static void main(String[] args) throws IOException {File file = new File("d:\\test.txt");FileInputStream fileInputStream = new FileInputStream(file);FileChannel channel = fileInputStream.getChannel();ByteBuffer allocate = ByteBuffer.allocate((int) file.length());channel.read(allocate);System.out.println(new String(allocate.array()));fileInputStream.close();}
}

package com.example.demo01.netty.nio;import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;public class NioTrancfer {public static void main(String[] args) throws Exception {FileInputStream fileInputStream = new FileInputStream("d:\\1.jpeg");FileOutputStream fileOutputStream = new FileOutputStream("d:\\2.jpeg");FileChannel sourceChannel = fileInputStream.getChannel();FileChannel destChannel = fileOutputStream.getChannel();destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());sourceChannel.close();destChannel.close();fileInputStream.close();fileOutputStream.close();}
}