JAR file in Java is a compressed format and is used for packaging of the deliverables. At times, you may want to manipulate this file.
Below example indicates a scenario for the same.
import java.util.jar.*;
import java.io.*;
public class RetrievingJarEntry
{
public static void main(String args[])
{
RetrievingJarEntry retrievingJarEntry = new RetrievingJarEntry();
retrievingJarEntry.proceed();
}
private void proceed()
{
String sourceJarFile = “files/contacts.jar”;
String sourceFile = “2.txt”;
String destFile = “files/new2.txt”;
try{
JarFile jarFile = new JarFile(sourceJarFile);
JarEntry jarEntry = jarFile.getJarEntry(sourceFile);
System.out.println(“Found entry: ” + jarEntry);
if ( jarEntry != null)
{
//Getting the jarEntry into the inputStream
InputStream inputStream = jarFile.getInputStream(jarEntry);
//Creating a output stream to a new file of our choice
FileOutputStream fileOutputStream = new java.io.FileOutputStream(destFile);
System.out.println(“Attempting to create file: ” + destFile);
while (inputStream.available() 0)
{
fileOutputStream.write(inputStream.read());
}
System.out.println(“Created file: ” + destFile);
fileOutputStream.close();
inputStream.close();
}
}catch(IOException ioe)
{
System.out.println(“Exception: ” + ioe);
}
}
}
/*
Expected output:
[[email protected]]# java RetrievingJarEntry
Found entry: 2.txt
Attempting to create file: files/new2.txt
Created file: files/new2.txt
*/
//Please note: You have to create a folder with name files and a jar file contacts.jar which has files 1.txt, 2.txt and 3.txt
