Read a zip file inside zip file

Question

I have zip file which is inside a folder in zip file please suggest me how to read it using zip input stream.

E.G.:

abc.zip
    |
      documents/bcd.zip

How to read a zip file inside zip file?

Answer 1

I have written a code that can unzip all zip files inside a zip file. It can even unzip to n levels of compression. Like for example if you had a zip file inside a zip, inside a zip ( and so on) it would extract all of them. Use the zipFileExtract method of this class and pass the source zip file and destination directory as an argument.

import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class RecursiveFileExtract {
    private static final int BUFFER_SIZE = 4096;
    private static Queue<File> current;
    private static List<File> visited;

    public static void zipFileExtract(File sourceZipFile, File destinationDirectory) {
        Path temp = null;
        if(!destinationDirectory.exists())
        {
            destinationDirectory.mkdirs();
        }
        try {
            temp = Files.move(Paths.get(sourceZipFile.getAbsolutePath()), Paths.get(destinationDirectory.getAbsolutePath()+File.separator+sourceZipFile.getName()));
        } catch (IOException e) {
            e.printStackTrace();
        }
        File zipFile = new File(temp.toAbsolutePath().toString());
        current = new ConcurrentLinkedQueue<>();
        visited = new ArrayList<>();
        current.add(zipFile);
        do {
            unzipCurrent();
            zipFinder(destinationDirectory);
        }
        while (!current.isEmpty());
    }

    private static void zipFinder(File directory) {
        try {
            if (directory != null) {
                File fileArray[] = directory.listFiles();
                if (fileArray != null) {
                    for (File file : fileArray) {
                        if (file != null) {
                            if (file.isDirectory()) {
                                zipFinder(file);
                            } else {
                                if (file.getName().endsWith(".zip")) {
                                    if (!visited.contains(file)) {
                                        current.add(file);
                                    }
                                }
                            }
                        }
                    }
                }
            }
        } catch (Exception e) {
            System.out.println(e.getLocalizedMessage());
        }
    }

    private static void unzipCurrent() {
        try {
            while (!current.isEmpty()) {
                File file = current.remove();
                visited.add(file);
                File zipDirectory = new File(file.getParentFile().getAbsolutePath());
                unzip(file.getAbsolutePath(), zipDirectory.getAbsolutePath());
            }
        } catch (Exception e) {
            System.out.println(e.getLocalizedMessage());
        }
    }

    public static void unzip(String zipFilePath, String destDirectory) {
        try {
            ZipInputStream zipIn = new ZipInputStream(new FileInputStream(zipFilePath));
            ZipEntry entry = zipIn.getNextEntry();

            while (entry != null) {
                String filePath = destDirectory + File.separator + entry.getName();
                if (!entry.isDirectory()) {
                    extractFile(zipIn, filePath);
                } else {

                    File dir = new File(filePath);
                    Boolean result = dir.mkdir();
                }
                zipIn.closeEntry();
                entry = zipIn.getNextEntry();
            }
            zipIn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void extractFile(ZipInputStream zipIn, String filePath) {
        try {
            File file = new File(filePath);
            File parentFile = file.getParentFile();
            if (!parentFile.exists()) {
                Boolean result = parentFile.mkdirs();
                if (!result) {
                    throw new Exception();
                }
            }
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(filePath));
            byte[] bytesIn = new byte[BUFFER_SIZE];
            int read = 0;
            while ((read = zipIn.read(bytesIn)) != -1) {
                bos.write(bytesIn, 0, read);
            }
            bos.close();
        } catch (Exception e) {
           System.out.println(e.getLocalizedMessage());
        }
    }
}

Answer 2

If you want to look through zip files within zip files recursively,

    public void lookupSomethingInZip(InputStream fileInputStream) throws IOException {
        ZipInputStream zipInputStream = new ZipInputStream(fileInputStream);
        String entryName = "";
        ZipEntry entry = zipInputStream.getNextEntry();
        while (entry!=null) {
            entryName = entry.getName();
            if (entryName.endsWith("zip")) {
                //recur if the entry is a zip file
                lookupSomethingInZip(zipInputStream);
            }
            //do other operation with the entries..

            entry=zipInputStream.getNextEntry();
        }
    }

Call the method with the file input stream derived from the file -

File file = new File(name);
lookupSomethingInZip(new FileInputStream(file));

Answer 3

The following code snippet lists the entries of a ZIP file inside another ZIP file. Adapt it to your needs. ZipFile uses ZipInputStreams underneath the hood.

The code snippet uses Apache Commons IO, specifically IOUtils.copy.

public static void readInnerZipFile(File zipFile, String innerZipFileEntryName) {
    ZipFile outerZipFile = null;
    File tempFile = null;
    FileOutputStream tempOut = null;
    ZipFile innerZipFile = null;
    try {
        outerZipFile = new ZipFile(zipFile);
        tempFile = File.createTempFile("tempFile", "zip");
        tempOut = new FileOutputStream(tempFile);
        IOUtils.copy( //
                outerZipFile.getInputStream(new ZipEntry(innerZipFileEntryName)), //
                tempOut);
        innerZipFile = new ZipFile(tempFile);
        Enumeration<? extends ZipEntry> entries = innerZipFile.entries();
        while (entries.hasMoreElements()) {
            ZipEntry entry = entries.nextElement();
            System.out.println(entry);
            // InputStream entryIn = innerZipFile.getInputStream(entry);
        }

    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        // Make sure to clean up your I/O streams
        try {
            if (outerZipFile != null)
                outerZipFile.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        IOUtils.closeQuietly(tempOut);
        if (tempFile != null && !tempFile.delete()) {
            System.out.println("Could not delete " + tempFile);
        }
        try {
            if (innerZipFile != null)
                innerZipFile.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public static void main(String[] args) {
    readInnerZipFile(new File("abc.zip"), "documents/bcd.zip");
}

Answer 4

Finally got it to work fixing Manas Maji's answer. Minimal solution:

import java.io.*;
import java.nio.file.*;
import java.util.zip.*;
import org.slf4j.*;

public void readZipFileRecursive(final Path zipFile) {
  try (final InputStream zipFileStream = Files.newInputStream(zipFile)) {
    this.readZipFileStream(zipFileStream);
  } catch (IOException e) {
    LOG.error("error reading zip file %s!", zipFile, e);
  }
}

private void readZipFileStream(final InputStream zipFileStream) {
  final ZipInputStream zipInputStream = new ZipInputStream(zipFileStream);
  ZipEntry zipEntry;
  try {
    while ((zipEntry = zipInputStream.getNextEntry()) != null) {
      LOG.info("name of zip entry: {}", zipEntry.getName());
      if (!zipEntry.isDirectory() && zipEntry.getName().endsWith(".zip")) {
        this.readZipFileStream(zipInputStream); // recursion
      }
    }
  } catch (IOException e) {
    LOG.error("error reading zip file stream", e);
  }
}

Care: don't close stream in recursive method.