With this example we are going to demonstrate how to calculate the CRC-32 checksum of a ZipEntry. In short, to calculate the CRC-32 checksum of a ZipEntry you should:
- Create a new ZipFile and open it for reading.
- Get the Enumeration of the ZipFile entries, with
entries()API method of ZipFile and iterate through each one of them. - For each one of the entries get the long
CRC-32 checksumof the uncompressed entry, usinggetCrc()API method of ZipEntry. - Close the ZipFile, with
close()API method of ZipFile.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
import java.io.IOException;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
public class CalculateCRC32ChecksumOfZipEntry {
public static void main(String[] args) {
ZipFile zipFile = null;
try {
// open a zip file for reading
zipFile = new ZipFile("c:/archive.zip");
// get an enumeration of the ZIP file entries
Enumeration<? extends ZipEntry> e = zipFile.entries();
while (e.hasMoreElements()) {
ZipEntry entry = e.nextElement();
// get the name of the entry
String entryName = entry.getName();
// get the CRC-32 checksum of the uncompressed entry data, or -1 if not known
long crc = entry.getCrc();
System.out.println(entryName + " with CRC-32: " + crc);
}
}
catch (IOException ioe) {
System.out.println("Error opening zip file" + ioe);
}
finally {
try {
if (zipFile!=null) {
zipFile.close();
}
}
catch (IOException ioe) {
System.out.println("Error while closing zip file" + ioe);
}
}
}
}
This was an example of how to calculate the CRC-32 checksum of a ZipEntry in Java.
