DotNetZip (Ionic.Zip.dll) doesn't work with compress Chinese File or Folder name

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07-10-2024

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DotNetZip (Ionic.Zip.dll) and Chinese File Names: A Compression Conundrum

Have you ever encountered a frustrating situation where you couldn't compress files with Chinese names using DotNetZip (Ionic.Zip.dll)? This is a common issue, especially when dealing with filenames containing non-ASCII characters. This article will explore the root cause of this problem and provide practical solutions to ensure successful compression regardless of file name encoding.

The Scenario:

Let's assume you have a folder named "中文文件" (Chinese File) containing several files. You try to compress this folder using DotNetZip with the following code:

using Ionic.Zip;

// ...

ZipFile zip = new ZipFile();
zip.AddDirectory("中文文件");
zip.Save("compressed.zip"); 

Upon execution, you may encounter an error or find that the compressed archive only contains empty files or incorrect file names.

The Root of the Problem:

The core issue lies in the way DotNetZip handles file names. It relies on the default system encoding, which is often set to ASCII. Chinese characters fall outside the ASCII character set and are encoded using a different character encoding like UTF-8. This mismatch leads to inconsistent interpretations of file names during compression and decompression.

Solutions and Workarounds:

1. Explicitly Setting Encoding:

   • The most reliable solution is to set the encoding of the ZipFile object to UTF-8 before adding files. This ensures consistent encoding throughout the compression process.

   using Ionic.Zip;
   using System.Text;
   
   // ...
   
   ZipFile zip = new ZipFile();
   zip.Encoding = Encoding.UTF8; 
   zip.AddDirectory("中文文件");
   zip.Save("compressed.zip");
   

2. Using the Correct File Name:

   • Another approach is to explicitly specify the file name using UTF-8 encoded bytes before adding it to the archive.

   using Ionic.Zip;
   using System.Text;
   
   // ...
   
   ZipFile zip = new ZipFile();
   string fileName = "中文文件";
   byte[] fileNameBytes = Encoding.UTF8.GetBytes(fileName);
   zip.AddDirectory(fileNameBytes);
   zip.Save("compressed.zip");
   

3. Alternative Library:

   • If you frequently encounter encoding issues, consider exploring other compression libraries like SharpZipLib or DotNetZip alternative. These libraries might offer improved support for non-ASCII characters.

Important Considerations:

• File System Encoding: Ensure your file system uses a consistent encoding to avoid issues when reading and writing files.
• Operating System Compatibility: While UTF-8 is widely adopted, certain operating systems or file systems might have different default encoding configurations. Be mindful of this when dealing with cross-platform scenarios.

Conclusion:

Successfully compressing files with Chinese names using DotNetZip requires careful handling of character encoding. By explicitly setting the encoding to UTF-8 or using encoded file names, you can overcome the encoding mismatch and achieve reliable compression results. Always prioritize a consistent encoding strategy to prevent unexpected issues in your file manipulation processes.