文件夹复制功能的实现

2.9 文件夹的复制

package file;

import java.io.*;

public class Demo4 {
 /*
 5.将C盘中的a.txt全部剪切到D盘中
 已升级，可复制文件夹和文件
 */
 public static void main(String[] args) throws IOException {
     File fileStart = new File("E:\\java课程及工具\\课程\\Java_QF\\软件\\java编程工具\\ideaIU-2021.3.3.exe");
     File fileEnd = new File("C:\\Users\\86178\\Desktop\\测试");
     Long start = System.currentTimeMillis();
     creationDirectory(fileStart , fileEnd);
     Long end = System.currentTimeMillis();
     System.out.println((end - start)/1000);
 }

 //先保证所有的文件夹会通过递归的方式创建
 private static void creationDirectory(File fileStart, File fileEnd) throws IOException {
     if (fileStart.isDirectory()){
         /*
         使用新的file对象，避免地址传递导致数据异常
         获取当前文件夹的绝对路径，并创建
         */
         File directoryEnd = new File(fileEnd , fileStart.getName());
         directoryEnd.mkdir();
         //获取文件夹内的所有文件对象，并判断是否有文件夹
         File[] files = fileStart.listFiles();
         for (File file : files) {
             File directoryName = new File(fileStart.getAbsolutePath() , file.getName());
             if (file.isDirectory()){
                 creationDirectory(directoryName , directoryEnd);
             }else{
                 cutFile(directoryName , directoryEnd);
             }
         }
     }else{
         cutFile(fileStart , fileEnd);
     }
 }

 //文件的IO字节流
 private static void cutFile(File fileStart, File fileEnd) throws IOException {
     fileEnd = new File(fileEnd , fileStart.getName());
     OutputStream ops = new FileOutputStream(fileEnd);
     InputStream ips = new FileInputStream(fileStart);
//        copyFile_1(ops , ips);
     copyFile_2(ops , ips);
     ops.close();
     ips.close();
 }

 //高效流
 private static void copyFile_2(OutputStream ops, InputStream ips) throws IOException {
     BufferedInputStream bis = new BufferedInputStream(ips);
     BufferedOutputStream bos = new BufferedOutputStream(ops);
     byte[] bs = new byte[1024];
     int len;
     while ((len = bis.read(bs)) != -1){
         bos.write(bs , 0 , len);
     }
     bos.close();
     bis.close();
 }

 //将复制的方法单独封装出来
 private static void copyFile_1(OutputStream ops, InputStream ips) throws IOException {
     byte[] bs = new byte[1024];
     int len;
     while ((len = ips.read(bs)) != -1){
         ops.write(bs , 0 , len);
     }
 }
}
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