- java.util.zip Package Classes
- java.util.zip - Home
- java.util.zip - Adler32
- java.util.zip - CheckedInputStream
- java.util.zip - CheckedOutputStream
- java.util.zip - CRC32
- java.util.zip - Deflater
- java.util.zip - DeflaterInputStream
- java.util.zip - DeflaterOutputStream
- java.util.zip - GZIPInputStream
- java.util.zip - GZIPOutputStream
- java.util.zip - Inflater
- java.util.zip - InflaterInputStream
- java.util.zip - InflaterOutputStream
- java.util.zip - ZipEntry
- java.util.zip - ZipFile
- java.util.zip - ZipInputStream
- java.util.zip - ZipOutputStream
- java.util.zip Package Extras
- java.util.zip - Exceptions
- java.util.zip - Error
- java.util.zip Useful Resources
- java.util.zip - Quick Guide
- java.util.zip - Useful Resources
- java.util.zip - Discussion
java.util.zip.ZipEntry.setCrc() Method Example
Description
The java.util.zip.ZipEntry.setCrc(long crc) method sets the CRC-32 checksum of the uncompressed entry data.
Declaration
Following is the declaration for java.util.zip.ZipEntry.setCrc(long crc) method.
public void setCrc(long crc)
Parameters
IllegalArgumentException − if the specified CRC-32 value is less than 0 or greater than 0xFFFFFFFF.
Exceptions
crc − the CRC-32 value.
Pre-requisite
Create a file Hello.txt in D:> test > directory with the following content.
This is an example.
Example
The following example shows the usage of java.util.zip.ZipEntry.setCrc(long crc) method.
package com.tutorialspoint; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.Date; import java.util.Enumeration; import java.util.zip.CRC32; import java.util.zip.ZipEntry; import java.util.zip.ZipFile; import java.util.zip.ZipOutputStream; public class ZipEntryDemo { private static String SOURCE_FILE = "D:\\test\\Hello.txt"; private static String TARGET_FILE = "D:\\test\\Hello.zip"; public static void main(String[] args) { try { createZipFile(); readZipFile(); } catch(IOException ioe) { System.out.println("IOException : " + ioe); } } private static void createZipFile() throws IOException{ FileOutputStream fout = new FileOutputStream(TARGET_FILE); ZipOutputStream zout = new ZipOutputStream(fout); FileInputStream fin = new FileInputStream(SOURCE_FILE); byte[] buffer = new byte[1024]; fin.read(buffer, 0, buffer.length); ZipEntry zipEntry = new ZipEntry(SOURCE_FILE); CRC32 crc = new CRC32(); zipEntry.setSize((long) buffer.length); crc.reset(); crc.update(buffer); zipEntry.setCrc(crc.getValue()); zipEntry.setTime(System.currentTimeMillis()); zout.putNextEntry(zipEntry); zout.write(buffer, 0, buffer.length); zout.closeEntry(); fin.close(); zout.close(); } private static void readZipFile() throws IOException{ final ZipFile file = new ZipFile(TARGET_FILE); System.out.println("Iterating over zip file : " + TARGET_FILE); try { final Enumeration<? extends ZipEntry> entries = file.entries(); while (entries.hasMoreElements()) { final ZipEntry entry = entries.nextElement(); System.out.printf("File: %s Size %d Modified on %TD %n", entry.getName(), entry.getSize(), new Date(entry.getTime())); extractFile(entry, file.getInputStream(entry)); } System.out.printf("Zip file %s extracted successfully.", SOURCE_FILE); } finally { file.close(); } } private static void extractFile(final ZipEntry entry, InputStream is) throws IOException { FileOutputStream fos = null; try { fos = new FileOutputStream(entry.getName()); final byte[] buf = new byte[1024]; int read = 0; int length; while ((length = is.read(buf, 0, buf.length)) >= 0) { fos.write(buf, 0, length); } } catch (IOException ioex) { fos.close(); } } }
Let us compile and run the above program, this will produce the following result −
Iterating over zip file : D:\test\Hello.zip File: D:\test\Hello.txt Size 1024 Modified on 05/20/17 Zip file D:\test\Hello.txt extracted successfully.
javazip_zipentry.htm
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