IO文件拷贝

package myio;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class IoDemo4 {
    public static void main(String[] args) throws IOException {
        FileInputStream fis = new FileInputStream("D:\\你的文件路径\\b.txt");
        FileOutputStream fos = new FileOutputStream("D:\\你的文件路径\\copy.txt");
        int b;
        while (( b = fis.read()) != -1){
            fos.write(b);
        }
        fis.close();
        fos.close();
    }
}

弊端和解决方法

FileInputStream一次只能读取一个字节，速度太慢

如果文件过大可以使用多个字节读取

package myio;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class IoDemo4 {
    public static void main(String[] args) throws IOException {
        long sta = System.currentTimeMillis();
        FileInputStream fis = new FileInputStream("D:\\你的文件路径\\ceshi.mp3");
        FileOutputStream fos = new FileOutputStream("D:\\你的文件路径\\copy.mp3");
        int len;
        byte[] bytes = new byte[1024 * 1024 * 5];
        while ((len = fis.read(bytes)) != -1) {
            fos.write(bytes, 0, len);
        }
        fis.close();
        fos.close();
        long end = System.currentTimeMillis();
        System.out.println(end - sta);

    }
}