Putting bat file inside a jar file

Question

I have a java class that uses a bat file to execute commands. However I developed it in Eclipse IDE. It works fine in there. But as I export it in a jar file, it fails to find the bat file that was included.(gives me an IOException)

The file structure in eclipse is as follows :

Project1
---->src
------>com.myproj
-------->BatFileRead.java
----md.bat
----ul.bat

md.bat and ul.bat is same level as src directory. After jarring it src folder disappears.

Could someone help me with this. Thanks

Answer 1

In order to execute the command, you'll have to extract the bat file afterwards. You can't run executables which are inside jar files. Basically you'll need to open the batch file entry in the jar file as an input stream, and copy the data to a FileOutputStream on disk. You won't be able to execute it until it's a proper standalone file on the file system.

If you're already trying to extract it, chances are you're using getResource or getResourceAsStream slightly incorrectly. This is easy to do, because it depends whether you're calling ClassLoader.getResourceAsStream or Class.getResourceAsStream. The first only ever uses absolute paths (implicitly) and the second can use either absolute or relative paths. For example, in your case you'd want:

BatFileRead.class.getResourceAsStream("/md.bat")

or

BatFileRead.class.getClassLoader().getResourceAsStream("md.bat")

Have you checked that the bat files are definitely ending up in the jar file? Just list the contents with

jar tvf file.jar

to see what's in there.

Answer 2

Try copying file.jar to file.zip, and opening file.zip (e.g. just double clicking, or using e.g. 7-Zip). Can you find your .bat files inside? If the .bat file isn't there, you have to add the .bat file to your Eclipse project, and rebuild in Eclipse. If the .bat file is there, but you still get an IOException opening it from you .java application, then please post the code snippet triggering the IOException, and please give a full listing of file.zip (get the listing by extracting file.zip to C:\testdir, and running dir /s C:\testdir in the command line).

Please note that Jon Skeet is right that although it is possible to open any file in the .jar file as an InputStream using java.lang.Class.getResourceAsStream and java.lang.ClassLoader.getResourceAsStream (see tutorial or find them in the Java API docs), but in order to execute a .bat file inside, you have to extract the .jar file first.

Answer 3

Well this can be very dangerous. Be sure to use gloves when dealing with the BAT. They bite and quite painfull. Also try getting jar that has a big enough opening, although the bats will fit almost through any hole.

Good luck, and don't try this at home. This is done by professionals.

Answer 4

There needs to be an actual in the actual file system for the Windows shell to read.

public void runBat() {
  InputStream is = BatFileRead.class.getClassLoader().getResourceAsStream("md.bat");
  File batFile = new File ( System.getProperty( "java.io.tmpdir"), "md.bat");
  OutputStream os = new FileOutputStream( batfile );
  byte[] buffer = new byte[1024];
  int read = -1;
  while( (read = is.read(buffer)) != -1 ) {
   os.write( buffer, 0, read );
  }
  Runtime.getRuntime().exec(file.getAbsolutePath());
}

Answer 5

Thanks, it is really very helpful