提取 ZIP 文件失败 - 里面没有文件，提取后扩展名为 .zip25

Question

I was trying to extract the ZIP file from my Linux, I'm able to extract it, but the expected output is failing/wrong. The extract file suddenly has no files inside and the folder extracted has.zip25 extension. I searched on this, and there is saying that it is corrupted. However, I don't think it is corrupted because I am able to open and extract the zip files perfectly in local (Windows directory).

Example:

Zip file: FolderZip.zip

After extract: FolderZip.zip25 (Note: This is already extracted but still has.zip25 extension, also the files inside are missing).

Below is my code, I've worked on this for almost a month, but still can't figure it out. Can someone help me to figure out what did I do wrong?

public void unZipFolder(String zipFile, String outputFolder){
        byte[] buffer = new byte[1024];

        System.out.println("ZipFileLocation: " + zipFile);
        LOG.info(" ZipFileLocation: " + zipFile);

        File folder = new File(outputFolder);
        if(!folder.exists())folder.mkdirs();

        try{
            FileInputStream fis = new FileInputStream(zipFile);
            ZipInputStream zis = new ZipInputStream(fis);
            ZipEntry ze = zis.getNextEntry();
            
            while(ze != null) {
                new File(folder.getParent()).mkdirs();
                FileOutputStream fos = new FileOutputStream(folder);
                File newFile = new File(outputFolder + FilenameUtils.indexOfLastSeparator(ze.getName()));
                                
                if (ze.isDirectory()) {
                    if (!newFile.isDirectory() && !newFile.mkdirs()) {
                        throw new IOException("Failed to create directory " + newFile);
                    }else if(ze.isDirectory()){
                        newFile.mkdirs();
                        continue;
                    }else{
                        int len;
                        while ((len = zis.read(buffer)) >= 0) {
                            fos.write(buffer, 0, len);
                        }
                        
                        System.out.println("File Unzip: " + newFile);
                        LOG.info(" File Unzip: " + newFile);
                        newFile.mkdirs();
                        fos.close();
                        zis.closeEntry();
                        ze = zis.getNextEntry();
                    }
                }    
                
                boolean result = Files.deleteIfExists(Paths.get(zipFile));
                if (result) {
                    System.out.println("ZipFile is deleted....");
                } else {
                    System.out.println("Unable to delete the file.....");
              }
            }
            zis.closeEntry();
            zis.close();
            fis.close();
         }catch(IOException ex){
            ex.printStackTrace();
     }
}

Answer 1

I'd love to be able to tell you exactly what's wrong with your code, but FileOutputStream fos = new FileOutputStream(folder); throws an exception because, well, folder is, a directory, so you can't write to it.

I'm also scratching my head over what your expecting new File(folder.getParent()).mkdirs(); to do.

I basically threw out your code and started again with...

public void unZipFolder(File zipFile, File outputFolder) throws IOException {
    byte[] buffer = new byte[1024];

    System.out.println("ZipFileLocation: " + zipFile);
    System.out.println("outputFolder = " + outputFolder);

    if (!outputFolder.exists() && !outputFolder.mkdirs()) {
        throw new IOException("Unable to create output folder: " + outputFolder);
    } else if (outputFolder.exists() && !outputFolder.isDirectory()) {
        throw new IOException("Output is not a directory: " + outputFolder);
    }

    try (ZipFile zipper = new ZipFile(zipFile)) {
        Enumeration<? extends ZipEntry> entries = zipper.entries();
        while (entries.hasMoreElements()) {
            ZipEntry ze = entries.nextElement();
            File destination = new File(outputFolder, ze.getName());
            if (ze.isDirectory()) {
                if (!destination.exists() && !destination.mkdirs()) {
                    throw new IOException("Could not create directory: " + destination);
                }
            } else {
                System.out.println("Writing " + destination);
                try (InputStream is = zipper.getInputStream(ze); FileOutputStream fos = new FileOutputStream(destination)) {
                    // You could use is.transferTo(fos) here but I'm a grump old coder
                    byte[] bytes = new byte[1024 * 4];
                    int bytesRead = -1;
                    while ((bytesRead = is.read(bytes)) != -1) {
                        fos.write(bytes, 0, bytesRead);
                    }
                }
            }
        }
    }
}

Now, what's important to know about this is, it expects the directory contents of the zip files to be relative (ie no root directory information). If your zip file does contain root directory information (ie C:/... or /... ), then you're going to need to clean that up yourself.

Now, if you have trouble with this, I would suggest commenting out the "extraction" portion of the code and placing in more System.out.println statements

transferTo

After reading through the code for transferTo , it's basically doing the same thing that the code example above is doing - so, if you wanted to reduce the code complexity (and reduce the risk of possible bugs), you could use it - been some what old school, I'd probably still do it the "old way" in order to provide support for progress monitoring of some kind - but that's beyond the scope of the question.

"Security issues"

This ones a little harder to tie down, as no solution is 100% safe.

I modified the above code to use something like...

Path parent = outputFolder.toPath().toAbsolutePath();
String name = "../" + ze.getName();
Path child = parent.resolveSibling(new File(outputFolder, name).toPath());

And this ended up throwing a NoSuchFileException , so, at least you could "fail fast", assuming that's what you want.

You might also consider removing .. , leading / or leading path specifications in an attempt to make the path "relative", but that could become complicated as something like somePath/../file could still be valid within your use case.