How can I make my Java generated zip file look like WinZip generated
I have a class that zips the contents of a directory into a zip file. The code I am using is below. The problem I am running into is that the zip file I created cannot be read by the application I upload it to. However, if I unzip the zip file that is generated and use WinZip to zip it back again, the file can be used. I have no control over the target application that downloads the zip, so I can make my file look like a WinZip-generated version. I opened each zip file using WinZip's detailed diagnostic feature and I see a lot of differences in the files generated, but I don't understand which ones might be causing the problem. See the bottom of the question for examples.
package com.mycompany.utils;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
import org.apache.log4j.Logger;
public class FileZipper {
private static final Logger LOGGER = Logger.getLogger(FileZipper.class);
private String destinationZipFile;
private String sourceDirectory;
List<String> fileList;
private File zipFile;
public File getZipFile() {
return zipFile;
}
/**
* Zips a source directory into the destination zip file
*
* @param source
* @param destination
*/
FileZipper(String source, String destination) {
LOGGER.info("Zipping source directory: "+source);
LOGGER.info("To destination zip file: "+destination);
this.destinationZipFile = destination;
this.sourceDirectory = source;
fileList = new ArrayList<String>();
generateFileList(new File(sourceDirectory));
compressDirectoryContentsToZip(sourceDirectory, destinationZipFile);
}
/**
* Traverse a directory and get all files, and add the file into fileList
*
* @param node
* file or directory
*/
public void generateFileList(File node) {
// add file only
if (node.isFile()) {
fileList.add(generateZipEntry(node.getAbsoluteFile().toString()));
}
if (node.isDirectory()) {
if(node.toString() != sourceDirectory) {
fileList.add(generateZipEntry(node.getAbsoluteFile().toString()));
}
String[] subNodes = node.list();
for (String filename : subNodes) {
generateFileList(new File(node, filename));
}
}
}
/**
* Compress a directory to a zip file
* @param sourceDirectory
* @param destinationZipFile
*/
public void compressDirectoryContentsToZip(String sourceDirectory,
String destinationZipFile) {
this.zipFile = new File(destinationZipFile);
byte[] buffer = new byte[4096];
try {
FileOutputStream fos = new FileOutputStream(destinationZipFile);
BufferedOutputStream bos = new BufferedOutputStream(fos);
ZipOutputStream zos = new ZipOutputStream(bos);
zos.setMethod(ZipOutputStream.DEFLATED);
LOGGER.info("Zipping to : " + destinationZipFile);
for (String entry : this.fileList) {
long fileSizeInBytes = new File(sourceDirectory +
File.separator + entry).length();
if(new File(sourceDirectory + File.separator + entry).isFile()) {
LOGGER.info("File Added : " + entry + " ("+String.valueOf(fileSizeInBytes)+" bytes)");
ZipEntry ze = new ZipEntry(entry);
zos.putNextEntry(ze);
FileInputStream in = new FileInputStream(sourceDirectory
+ File.separator + entry);
int len;
while ((len = in.read(buffer)) > 0) {
zos.write(buffer, 0, len);
}
in.close();
zos.closeEntry();
} else if(new File(sourceDirectory + File.separator + entry).isDirectory()) {
LOGGER.info("Directory Added : " + entry);
ZipEntry ze = new ZipEntry(entry+File.separator);
zos.putNextEntry(ze);
zos.closeEntry();
} else {
LOGGER.warn("Not a file or directory: "+entry);
}
}
zos.closeEntry();
zos.close();
LOGGER.info("Zipping completed successfully");
} catch (IOException ex) {
LOGGER.error(ex);
System.exit(1);
}
LOGGER.info("Generated zip file: "+ destinationZipFile);
}
/**
* Format the filename for archiving by removing the path
* of the source directory
*
* @param file
* @return
*/
private String generateZipEntry(String file) {
LOGGER.debug("Stripping '"+file+"' to '"
+file.substring(sourceDirectory.length() + 1, file.length())+"'");
return file.substring(sourceDirectory.length() + 1, file.length());
}
}
Thus, the output I see as a result of processing the zip file in WinZip is as follows:
Broken file
Archive: C:\Users\conor\Desktop\dp-export-2\dp-export-2.zip 3573 bytes 2014-11-04 20:03:22 Current Location part 1 offset 3551 End central directory record PK0506 (4+18) ========================================== location of end-of-central-dir record: 3551 (0x00000ddf) bytes part number of this part (0000): 1 part number of start of central dir (0000): 1 number of entries in central dir in this part: 1 total number of entries in central dir: 1 size of central dir: 56 (0x00000038) bytes relative offset of central dir: 3495 (0x00000da7) bytes zipfile comment length: 0 Current Location part 1 offset 3495 Central directory entry PK0102 (4+42): #1 ====================================== part number in which file begins (0000): 1 relative offset of local header: 0 (0x00000000) bytes version made by operating system (00): MS-DOS, OS/2, NT FAT version made by zip software (20): 2.0 operat. system version needed to extract (00): MS-DOS, OS/2, NT FAT unzip software version needed to extract (20): 2.0 general purpose bit flag (0x0808) (bit 15..0): 0000.1000 0000.1000 file security status (bit 0): not encrypted extended local header (bit 3): yes UTF-8 names (bit 11): yes compression method (08): deflated compression sub-type (deflation): normal file last modified on (0x00004564 0x0000a06a): 2014-11-04 20:03:20 32-bit CRC value: 0x07d797c8 compressed size: 3439 bytes uncompressed size: 24021 bytes length of filename: 10 characters length of extra field: 0 bytes length of file comment: 0 characters internal file attributes: 0x0000 apparent file type: binary external file attributes: 0x00000000 non-MSDOS external file attributes: 0x000000 MS-DOS file attributes (0x00): none filename: export.xml Current Location part 1 offset 0 Local directory entry PK0304 (4+26): #1 ------------------------------------ operat. system version needed to extract (00): MS-DOS, OS/2, NT FAT unzip software version needed to extract (20): 2.0 general purpose bit flag (0x0808) (bit 15..0): 0000.1000 0000.1000 file security status (bit 0): not encrypted extended local header (bit 3): yes UTF-8 names (bit 11): yes compression method (08): deflated compression sub-type (deflation): normal file last modified on (0x00004564 0x0000a06a): 2014-11-04 20:03:20 32-bit CRC value: 0x00000000 compressed size: 0 bytes uncompressed size: 0 bytes note: "real" crc and sizes are in the extended local header length of filename: 10 characters length of extra field: 0 bytes filename: export.xml Testing export.xml OK Current Location part 1 offset 3479 Extended local dir entry PK0708 (4+12): #1 --------------------------------------- 32-bit CRC value: 0x07d797c8 compressed size: 3439 bytes uncompressed size: 24021 bytes No errors detected in compressed data of C:\Users\conor\Desktop\dp-export-2\dp-export-2.zip.
A working file that was re-zipped from a non-working file unzip
Archive: C:\Users\conor\Desktop\dp-export-2\dp-export-2b.zip 3564 bytes 2014-11-04 20:04:46 Current Location part 1 offset 3542 End central directory record PK0506 (4+18) ========================================== location of end-of-central-dir record: 3542 (0x00000dd6) bytes part number of this part (0000): 1 part number of start of central dir (0000): 1 number of entries in central dir in this part: 1 total number of entries in central dir: 1 size of central dir: 92 (0x0000005c) bytes relative offset of central dir: 3450 (0x00000d7a) bytes zipfile comment length: 0 Current Location part 1 offset 3450 Central directory entry PK0102 (4+42): #1 ====================================== part number in which file begins (0000): 1 relative offset of local header: 0 (0x00000000) bytes version made by operating system (00): MS-DOS, OS/2, NT FAT version made by zip software (20): 2.0 operat. system version needed to extract (00): MS-DOS, OS/2, NT FAT unzip software version needed to extract (20): 2.0 general purpose bit flag (0x0002) (bit 15..0): 0000.0000 0000.0010 file security status (bit 0): not encrypted extended local header (bit 3): no compression method (08): deflated compression sub-type (deflation): maximum file last modified on (0x00004564 0x0000a06a): 2014-11-04 20:03:20 32-bit CRC value: 0x07d797c8 compressed size: 3410 bytes uncompressed size: 24021 bytes length of filename: 10 characters length of extra field: 36 bytes length of file comment: 0 characters internal file attributes: 0x0001 apparent file type: text external file attributes: 0x00000020 non-MSDOS external file attributes: 0x000000 MS-DOS file attributes (0x20): arc filename: export.xml extra field 0x000a (PKWARE Win32 Filetimes), 4 header and 32 data bytes: The Extended Timestamps are: Creation Date: 2014-11-04 20:03:20 Last Modified Date: 2014-11-04 20:03:20 Last Accessed Date: 2014-11-04 20:03:20 Current Location part 1 offset 0 Local directory entry PK0304 (4+26): #1 ------------------------------------ operat. system version needed to extract (00): MS-DOS, OS/2, NT FAT unzip software version needed to extract (20): 2.0 general purpose bit flag (0x0002) (bit 15..0): 0000.0000 0000.0010 file security status (bit 0): not encrypted extended local header (bit 3): no compression method (08): deflated compression sub-type (deflation): maximum file last modified on (0x00004564 0x0000a06a): 2014-11-04 20:03:20 32-bit CRC value: 0x07d797c8 compressed size: 3410 bytes uncompressed size: 24021 bytes length of filename: 10 characters length of extra field: 0 bytes filename: export.xml Testing export.xml OK No errors detected in compressed data of C:\Users\conor\Desktop\dp-export-2\dp-export-2b.zip.
So obviously I can see differences in the results, but I don't understand why all the differences exist and I don't know which one is causing the failure. Any help in determining why the generated Java file might not please my target application would be of great help. I have a suspicion that the reason is the way the CRC is calculated by Java vs WinZip and added to the archive afterwards, but I have no experience with this kind of problem. My other theory is that it has to do with the internal attributes of the file. The example, which is not parsed, displays "export.xml" as binary data, but the WinZip version displays this as text.
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1 answer
I was working on the problem, I don't understand what the root cause was, but using the library org.apache.commons.compress the zip file can now be used. Tomorrow I will dig into it because I am curious to know what the difference is. Meanwhile, here's the updated class.
package com.mycompany.utils;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
import org.apache.commons.compress.archivers.zip.ZipArchiveOutputStream;
import org.apache.log4j.Logger;
public class FileZipper {
private static final Logger LOGGER = Logger.getLogger(OldFileZipper.class);
private String destinationZipFile;
private String sourceDirectory;
List<String> fileList;
private File zipFile;
public File getZipFile() {
return zipFile;
}
/**
* Zips a source directory into the destination zip file
*
* @param source
* @param destination
*/
FileZipper(String source, String destination) {
LOGGER.info("Zipping source directory: "+source);
LOGGER.info("To destination zip file: "+destination);
this.destinationZipFile = destination;
this.sourceDirectory = source;
fileList = new ArrayList<String>();
generateFileList(new File(sourceDirectory));
compressDirectoryContentsToZip(sourceDirectory, destinationZipFile);
}
/**
* Traverse a directory and get all files, and add the file into fileList
*
* @param node
* file or directory
*/
public void generateFileList(File node) {
// add file only
if (node.isFile()) {
fileList.add(generateZipEntry(node.getAbsoluteFile().toString()));
}
if (node.isDirectory()) {
if(node.toString() != sourceDirectory) {
fileList.add(generateZipEntry(node.getAbsoluteFile().toString()));
}
String[] subNodes = node.list();
for (String filename : subNodes) {
generateFileList(new File(node, filename));
}
}
}
/**
* Compress a directory to a zip file
* @param sourceDirectory
* @param destinationZipFile
*/
public void compressDirectoryContentsToZip(String sourceDirectory, String destinationZipFile) {
this.zipFile = new File(destinationZipFile);
byte[] buffer = new byte[4096];
try {
FileOutputStream fos = new FileOutputStream(destinationZipFile);
BufferedOutputStream bos = new BufferedOutputStream(fos);
ZipArchiveOutputStream zos = new ZipArchiveOutputStream(bos);
zos.setMethod(ZipArchiveOutputStream.DEFLATED);
zos.setLevel(0);
LOGGER.info("Zipping to : " + destinationZipFile);
for (String entry : this.fileList) {
long fileSizeInBytes = new File(sourceDirectory + File.separator + entry).length();
if(new File(sourceDirectory + File.separator + entry).isFile()) {
LOGGER.info("File Added : " + entry + " ("+String.valueOf(fileSizeInBytes)+" bytes)");
ZipArchiveEntry ze = new ZipArchiveEntry(entry);
zos.putArchiveEntry(ze);
FileInputStream in = new FileInputStream(sourceDirectory
+ File.separator + entry);
int len;
while ((len = in.read(buffer)) > 0) {
zos.write(buffer, 0, len);
}
in.close();
zos.closeArchiveEntry();
} else if(new File(sourceDirectory + File.separator + entry).isDirectory()) {
LOGGER.info("Directory Added : " + entry);
ZipArchiveEntry ze = new ZipArchiveEntry(entry+File.separator);
zos.putArchiveEntry(ze);
zos.closeArchiveEntry();
} else {
LOGGER.warn("Not a file or directory: "+entry);
}
}
zos.close();
LOGGER.info("Zipping completed successfully");
} catch (IOException ex) {
LOGGER.error(ex);
System.exit(1);
}
LOGGER.info("Generated zip file: "+ destinationZipFile);
}
/**
* Format the filename for archiving by removing the path
* of the source directory
*
* @param file
* @return
*/
private String generateZipEntry(String file) {
LOGGER.debug("Stripping '"+file+"' to '"+file.substring(sourceDirectory.length() + 1, file.length())+"'");
return file.substring(sourceDirectory.length() + 1, file.length());
}
}
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