[Java知识库]netty（五） 【 transferTo 零拷贝实例】

前言：
在linux 中 transferTo 方法就可以完成传输，在 windows 中依次调用transferTo最多能传8M文件，需要分段传文件，而且要注意传输起点位置

模拟服务端实验源码：

package com.dev.nio.TRANSFERTO;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;

/**
 * @author :
 * @date :2022/3/29 下午 2:24
 * @description :
 * @modyified By:
 */
public class IOServer {
    public static void main(String[] args) throws Exception {
        //定义监听端口
        InetSocketAddress address = new InetSocketAddress(7001);
        //定义并打开一个通道
        ServerSocketChannel  serverSocketChannel = ServerSocketChannel.open();
        ServerSocket serverSocket = serverSocketChannel.socket();
        serverSocket.bind(address);

        //创建BUFFER
        ByteBuffer byteBuffer = ByteBuffer.allocate(4096);

        while (true){
            SocketChannel socketChannel = serverSocketChannel.accept();
            int readcount = 0;
            while (readcount!=-1){
                try {
                    readcount = socketChannel.read(byteBuffer);
                }catch (Exception e){
//                    e.printStackTrace();
                    break;
                }
                byteBuffer.rewind();//倒带 position=1   mark 作废
            }
        }

    }

}

模拟客户端实验源码：

package com.dev.nio.TRANSFERTO;

import java.io.FileInputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.channels.FileChannel;
import java.nio.channels.SocketChannel;

/**
 * @author : lei.yu
 * @date :2022/3/29 下午 2:24
 * @description : transferto 零拷贝客户端
 * @modyified By:
 */
public class clentServer {
    public static void main(String[] args) throws Exception {
        String fileName="d:\\1m.7z";//需要传输的文件
        SocketChannel socketChannel = SocketChannel.open();
        InetSocketAddress address = new InetSocketAddress("localhost", 7001);
        socketChannel.connect(address);
        //得到一个文件channel
        FileChannel fileChannel = new FileInputStream(fileName).getChannel();
        //准备发送
        long startTime = System.currentTimeMillis();
        //在linux 中 transferTo 方法就可以完成传输
        //在 windows  中依次调用transferTo最多能传8M文件，需要分段传文件，而且要注意传输起点位置
        //transferTo 底层零拷贝
        long transferCount = fileChannel.transferTo(0, fileChannel.size(), socketChannel);
        System.out.println("发送的总字节数="+transferCount+" 耗时："+(System.currentTimeMillis()-startTime));
        //关闭
        socketChannel.close();
        fileChannel.close();
    }


}

实验结果：