This article is about how to write a utility class for extracting files
and directories in a compressed zip archive, using built-in Java API.
The java.util.zip package provides the following classes for extracting files and directories from a ZIP archive:
The java.util.zip package provides the following classes for extracting files and directories from a ZIP archive:
- ZipInputStream:
this is the main class which can be used for reading zip file and
extracting files and directories (entries) within the archive. Here are
some important usages of this class:
- read a zip via its constructor ZipInputStream(FileInputStream)
- read entries of files and directories via method getNextEntry()
- read binary data of current entry via method read(byte)
- close current entry via method closeEntry()
- close the zip file via method close()
- ZipEntry: this class represents an entry in the zip file. Each file or directory is represented as a ZipEntry object. Its method getName() returns a String which represents path of the file/directory. The path is in the following form:folder_1/subfolder_1/subfolder_2/…/subfolder_n/file.ext
- ZipInputStream:
this is the main class which can be used for reading zip file and
extracting files and directories (entries) within the archive. Here are
some important usages of this class:
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
/**
* This utility extracts files and directories of a standard zip file to
* a destination directory.
* @author www.codejava.net
*
*/
public class UnzipUtility {
/**
* Size of the buffer to read/write data
*/
private static final int BUFFER_SIZE = 4096;
/**
* Extracts a zip file specified by the zipFilePath to a directory specified by
* destDirectory (will be created if does not exists)
* @param zipFilePath
* @param destDirectory
* @throws IOException
*/
public void unzip(String zipFilePath, String destDirectory) throws IOException {
File destDir = new File(destDirectory);
if (!destDir.exists()) {
destDir.mkdir();
}
ZipInputStream zipIn = new ZipInputStream(new FileInputStream(zipFilePath));
ZipEntry entry = zipIn.getNextEntry();
// iterates over entries in the zip file
while (entry != null) {
String filePath = destDirectory + File.separator + entry.getName();
if (!entry.isDirectory()) {
// if the entry is a file, extracts it
extractFile(zipIn, filePath);
} else {
// if the entry is a directory, make the directory
File dir = new File(filePath);
dir.mkdir();
}
zipIn.closeEntry();
entry = zipIn.getNextEntry();
}
zipIn.close();
}
/**
* Extracts a zip entry (file entry)
* @param zipIn
* @param filePath
* @throws IOException
*/
private void extractFile(ZipInputStream zipIn, String filePath) throws IOException {
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();
}
}
