Copy the files of java small practice

Requirements: the E disk folder aaa all content (including aaa folder) copied to disk F
realization of ideas:

• The file folder path E aaa disk package is a File object
• Create a copy function, function parameter file as a File object
• In the copy function
  • The first step: parameter file path judgment whether there exists into the second step, the output does not exist
  • Step 2: Use getPath () method to obtain the parameter file path, and replace the disc path F, and then packaged into a File object destFile
  • The third step: to determine whether the path is a file folder at the end
  • Step Four: If it is, get from all subfolders (including folders) and traversal, traversing the destFile to create the folder, and then copy a recursive function
  • Step five: If it is not, that end of the file, the file is read and copied to the corresponding disk F get directory
• Specific code as follows:

import java.io.*;

public class CopyDemo {
    public static void main(String[] args) throws Exception {
        long start = System.currentTimeMillis();
        String path = "E:/aaa";//文件夹（绝对）路径
        File file = new File(path);
        copyFile(file);
        long end = System.currentTimeMillis();
        System.out.println("复制共耗时："+(end-start)+"毫秒");

    }

    private static void copyFile(File file) throws Exception {
        //判断file对象的文件路径是否存在
        if(file.exists()){
            //F盘文件路径，File对象无论路径存在与否都可以创建
            File destFile = new File(file.getPath().replace("E:","F:"));

            if(file.isDirectory()){
                //file路径是文件夹结尾
                File[] files = file.listFiles();//file的子文件
                // 因为file是文件夹结尾才进入此for循环，所以此处destFile也是文件夹结尾
                for (File f :
                        files) {
                    if(!destFile.exists()){

                        //目标文件夹不存在则创建
                        destFile.mkdir();
                    }
                    copyFile(f);//递归
                }
            }else{
                //file路径是文件结尾，那么destFile路径也是文件结尾

                //读取文件对象
                InputStream is = new FileInputStream(file);

                //写入文件对象
                OutputStream os = new FileOutputStream(destFile);//destFile路径文件不存在会自动创建

                int len;//读取的有效字节个数
                byte[] b = new byte[1024];
                while ((len=is.read()) != -1){
                    //读取操作返回值为-1则说明读取完毕
                    os.write(len);//写入数据
                }
                is.close();//关闭写入
                os.close();//关闭读取
            }
        }else{
            System.out.println(file.getPath()+"不存在");
        }
    }
}