Home » Core Java » util » jar » List entries of JAR file Manifest

About Byron Kiourtzoglou

Byron Kiourtzoglou
Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.

List entries of JAR file Manifest

In this example we shall show you how to list entries of a JAR file Manifest. The manifest is a special file that contains information about the files packaged in a JAR file. To list the entries of a JAR file Manifest one should perform the following steps:

  • Create a new JarFile to read from the specified file.
  • Get the Manifest for that file, using the getManifest() API method of the JarFile.
  • Get the manifest entries, with the getEntries() API method. It returns a Map of String – Attributes key-value pairs.
  • For each entry get all attributes. An Iterator can be used over the String keys of the Map of entries to get the Attributes for each key.
  • Then a second Iterator can be used over the Attributes, to get the Attributes.Name, and getValue(Attributes.Name name) API method of the Attributes to get the value of each Attributes.Name.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;

import java.util.Iterator;
import java.util.Map;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

public class ListEntriesOfJARFileManifest {
	
	public static void main(String[] args) throws Exception {
		
		// create a new JAR file to read from the specified file
		JarFile jarfile = new JarFile("jsp-api.jar");

	    // get the manifest for that file
	    Manifest manifest = jarfile.getManifest();

	    // get the manifest entries
	    Map<String, Attributes> mfEntries = manifest.getEntries();

	    for (Iterator<String> it = mfEntries.keySet().iterator(); it.hasNext(); ) {
	    	
	
  String entryName = it.next();

	
  // get all attributes for the entry
	
  Attributes attrs = mfEntries.get(entryName);

	
  for (Iterator<Object> it2=attrs.keySet().iterator(); it2.hasNext(); ) {
	

Attributes.Name attrName = (Attributes.Name)it2.next();
	

String attrValue = attrs.getValue(attrName);
	

System.out.println(attrName + ":" + attrValue);
	
  }
	    }
		
	}

}

Output:

Implementation-Vendor:Apache Software Foundation
Specification-Title:Java API for JavaServer Pages
Implementation-Title:javax.servlet.jsp
Implementation-Version:2.2.FR
Specification-Version:2.2
Specification-Vendor:Sun Microsystems, Inc.

 
This was an example of how to list entries of a JAR file Manifest in Java.

(No Ratings Yet)
1 Comment Views Tweet it!

Do you want to know how to develop your skillset to become a Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you our best selling eBooks for FREE!

 

1. JPA Mini Book

2. JVM Troubleshooting Guide

3. JUnit Tutorial for Unit Testing

4. Java Annotations Tutorial

5. Java Interview Questions

6. Spring Interview Questions

7. Android UI Design

 

and many more ....

 

Receive Java & Developer job alerts in your Area

 

1
Leave a Reply

avatar
1 Comment threads
0 Thread replies
0 Followers
 
Most reacted comment
Hottest comment thread
1 Comment authors
Varun Khulbey Recent comment authors
  Subscribe  
newest oldest most voted
Notify of
Varun Khulbey
Guest
Varun Khulbey

Map mfEntries = manifest.getEntries();
This line is giving me empty map. can anyone help ?

Here is my code:

import java.io.*;
import java.util.Map;
import java.util.jar.*;

public class Demo {
public static void main(String[] args) throws IOException {
String manifest_destination_filePath = “D:\\lib3\\MANIFEST.MF”;
BufferedInputStream is = new BufferedInputStream(new FileInputStream(new File(manifest_destination_filePath)));
Manifest mf = new Manifest(is);
Map mfEntries = mf.getEntries();
System.out.println();

}
}