Java by API/java.util.jar/JarFile

JarFile: entries()

  
import java.io.IOException;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
public class Main {
  public static void main(String[] args) throws IOException {
    JarFile jf = new JarFile(args[0]);
    Enumeration e = jf.entries();
    while (e.hasMoreElements()) {
      JarEntry je = (JarEntry) e.nextElement();
      String name = je.getName();
      System.out.println(name);
    }
  }
}

JarFile: getManifest()

 
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 Main {
  public static void main(String[] argv) throws Exception {
    JarFile jarfile = new JarFile("filename.jar");
    Manifest manifest = jarfile.getManifest();
    Map map = manifest.getEntries();
    for (Iterator it = map.keySet().iterator(); it.hasNext();) {
      String entryName = (String) it.next();
      Attributes attrs = (Attributes) map.get(entryName);
      for (Iterator it2 = attrs.keySet().iterator(); it2.hasNext();) {
        Attributes.Name attrName = (Attributes.Name) it2.next();
        String attrValue = attrs.getValue(attrName);
      }
    }
  }
}

new JarFile(String name)

  
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.util.jar.JarFile;
import java.util.jar.Pack200;
public class Main {
  public static void main(String[] args) throws Exception {
    OutputStream out = null;
    JarFile f = new JarFile(args[0]);
    Pack200.Packer packer = Pack200.newPacker();
    out = new FileOutputStream(args[0] + ".pack");
    packer.pack(f, out);
    out.close();
  }
}