Open H2 Database from Classpath

Question

I've seen from the H2 documentation that you can open files on the classpath .

I've tried various URLs (eg jdbc:h2:classpath:/myDatabase ) when opening a connection, but none seem to find the resource - but when I try MyClass.class.getClassLoader().getResourceAsStream("myDatabase") it can find it it fine.

The database is on the classpath in src\\test\\resources .

Any ideas what I'm doing wrong?

Answer 1

You can locate the myDatabase file. When running locally and unpacked, eg from inside the IDE you can do:

URL res = MyClass.class.getResource("/myDatabase");
String url = "jdbc:h2:" + res.toString();

which will output the full resource path eg jdbc:h2:file:/home/.../classes/myDatabase

This won't work when you package your app as a JAR or WAR. In this case the myDatabase will be packaged inside a ZIP archive, to quote this post :

The main problem for both zipped databases and databases in the classpath is: you can't do real random access. You can only read from a stream. Random access is required, so it is simulated like this: When seek(pos) larger than current position, then a skip is made (which is basically a read). If the seek pos is smaller, then the stream is closed and re-opened. This is very slow.

ZIP support is read-only based on Advanced > Pluggable File System docs :

zip: read-only zip-file based file system. Format: zip:/zipFileName!/fileName.

You probably should supply the path to the myDatabase using command line arguments or system variable and keep it outside of packaged application.

Answer 2

this works for me... it creates the pher folder in the classpath and "pharmadatabase" is my database name. jdbc:h2:file:pher/~/pharmadatabase;

you can see the path below-

Answer 3

• If u check thi slink i think solve your problem.

  In this link provided windows and Linus/mac classpath settings.

  [1]: https://o7planning.org/en/11895/installing-h2-database-and-using-h2-console