extracting all the contents of a jar file

[mythily prakash]

hi,

Any one can tell me how to implement the command
"jar -xvf myjar.jar" programmatically.I've written the program as

 
import java.io.*;
import java.util.*;
import java.util.jar.*;
import java.util.zip.ZipException;
 
public class jara {
     public static void main (String args[])throws IOException,ZipException
     {
       JarFile jarFile = new JarFile("ex.jar");
       Enumeration en = jarFile.entries();
       while (en.hasMoreElements()) {
         String ent=proc(en.nextElement());
         extract(jarFile.getName(),ent);       
       }
     }
 
       public static String proc(Object obj) {
       JarEntry entry = (JarEntry)obj;
       String name = entry.getName();
       System.out.println("\nEntry Name: "+name);
       return(name);
       
     }
      public static void extract(String jarName,String entryName)throws IOException,ZipException
      {
      JarFile jar = new JarFile(jarName);
          System.out.println(jarName + " opened.");
 
          try {
             // Get the entry and its input stream.
 
             JarEntry entry = jar.getJarEntry(entryName);
 
             // If the entry is not null, extract it. Otherwise, print a 
             // message.
 
             if (entry != null) {
                // Get an input stream for the entry.
                
                InputStream entryStream = jar.getInputStream(entry);
 
                try {
                   // Create the output file (clobbering the file if it exists).
 
                   FileOutputStream file = new FileOutputStream(entry.getName());
 
                   try {
                      // Allocate a buffer for reading the entry data.
 
                      byte[] buffer = new byte[1024];
                      int bytesRead;
 
                      // Read the entry data and write it to the output file.
 
                      while ((bytesRead = entryStream.read(buffer)) != -1) {
                         file.write(buffer, 0, bytesRead);
                      }
 
                      System.out.println(entry.getName() + " extracted.");
                   }
                   finally {
                      file.close();
                   }
                }
                finally {
                   entryStream.close();
                }
             }
             else {
                System.out.println(entryName + " not found.");
             } // end if
          }
          finally {
             jar.close();
             System.out.println(jarName + " closed.");
          }
       }
     }
 

but it throws the following exception as:

Entry Name: META-INF/
ex.jar opened.
META-INF/ extracted.
ex.jar closed.

Entry Name: META-INF/MANIFEST.MF
ex.jar opened.
ex.jar closed.
Exception in thread "main" java.io.FileNotFoundException: META-INF\MANIFEST.MF (The system cannot find the path specified)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:201)
at java.io.FileOutputStream.<init>(FileOutputStream.java:92)
at jara.extract(jara.java:46)
at jara.main(jara.java:14)

Pls tell me how to recover from it.

[Joni Salonen]

You need to create the directory first:

File local = new File(entry.getName());
local.getParentFile().mkdirs();
FileOutputStream file = new FileOutputStream(local);

[mythily prakash]

Thank u Friend,
Here is my code :

import java.io.*;
import java.util.*;
import java.util.jar.*;
import java.util.zip.ZipException;
 
public class jara {
    public static void main (String args[])throws IOException,ZipException
    {
       JarFile jarFile = new JarFile("dirp.jar");
       Enumeration en = jarFile.entries();
       while (en.hasMoreElements()) {
         String ent=proc(en.nextElement());
         if(ent.indexOf("/")>0)
         {
         String fil=ent.substring(0,ent.indexOf("/"));
         System.out.println(fil);
         File local=new File(fil);
         if(!local.exists())
         local.mkdirs();
         }
         if(ent.indexOf(".")>0)
         {
         int n=ent.length();
         String fil1=ent.substring(ent.lastIndexOf("/")+1,n);
         System.out.println(fil1);
          extract(jarFile.getName(),ent);  
         }
         
        }
     }

       public static String proc(Object obj)
       {
       JarEntry entry = (JarEntry)obj;
       String name = entry.getName();
       System.out.println("\nEntry Name: "+name);
       return(name);
       }
 
       public static void extract(String jarName,String entryName)throws IOException,ZipException
      {
      JarFile jar = new JarFile(jarName);
          System.out.println(jarName + " opened.");
 
          try {
             // Get the entry and its input stream.
 
             JarEntry entry = jar.getJarEntry(entryName);
 
             // If the entry is not null, extract it. Otherwise, print a 
             // message.
 
             if (entry != null) {
                // Get an input stream for the entry.
                
                InputStream entryStream = jar.getInputStream(entry);
 
                try {
                   // Create the output file (clobbering the file if it exists).
 
                   FileOutputStream file = new FileOutputStream(entry.getName());
 
                   try {
                      // Allocate a buffer for reading the entry data.
 
                      byte[] buffer = new byte[1024];
                      int bytesRead;
 
                      // Read the entry data and write it to the output file.
 
                      while ((bytesRead = entryStream.read(buffer)) != -1) {
                         file.write(buffer, 0, bytesRead);
                      }
 
                      System.out.println(entry.getName() + " extracted.");
                   }
                   finally {
                      file.close();
                   }
                }
                finally {
                   entryStream.close();
                }
             }
             else {
                System.out.println(entryName + " not found.");
             } // end if
          }
          finally {
             jar.close();
             System.out.println(jarName + " closed.");
          }
       }
     }

Thank u somuch.!