使用 FileChannel 进行文件的复制拷贝

package com.yanchi;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;

/** * @author yanchi * @date 2022/6/30 14:04 */
public class FileChannelTest {
    
    public static void main(String[] args) {
    
        try (
                FileChannel from = new FileInputStream("data.txt").getChannel();
                FileChannel to = new FileOutputStream("to.txt").getChannel();
        ) {
    
        	// 一次最高只能传输 2g
            from.transferTo(0,from.size(),to);
        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }
}

由于以上方法最大只能传输 2G 的文件，下面的代码对以上代码进行优化！！

package com.yanchi;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;

/** * @author yanchi * @date 2022/6/30 14:04 */
public class FileChannelTest {
    
    public static void main(String[] args) {
    
        try (
                FileChannel from = new FileInputStream("data.txt").getChannel();
                FileChannel to = new FileOutputStream("to.txt").getChannel();
        ) {
    
            // 源文件字节数
            long size = from.size();
            // left 代表还剩下多少字节
            for (long left = size; left > 0;){
    
                left -= from.transferTo((size - left), left, to);
            }
        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }
}