Read an Access database embedded in a JAR file

Question

I have a Java program which uses UCanAccess to read an Access database. When I export my program to a JAR file I can't read the database file that is inside the JAR.

I tried with getClass().getResource("/Database.accdb").getPath() but it doesn't work.

How can I fix it?

I'm not sure you can, directly, you might have to extract the database from the jar and store it on the disk somewhere, having it embedded like this means the database would read-only (assuming you could read it from within the jar) — MadProgrammer, Feb 23 '16 at 23:14

Gord Thompson · Answer 1 · 2017-07-21T01:22:11.290

You cannot open the database file directly from the copy imbedded in the runnable JAR file. UCanAccess requires that the database file be a "real" file, so you'll need to extract it from the JAR and then open that copy.

For example, to extract the database from the JAR into a temporary file:

java.io.File dbFile = java.io.File.createTempFile("tempdb", ".accdb");
dbFile.deleteOnExit();
java.nio.file.Files.copy(
        YourClassName.class.getResourceAsStream("/stuff.accdb"), 
        dbFile.toPath(), 
        java.nio.file.StandardCopyOption.REPLACE_EXISTING);
String connStr = String.format(
        "jdbc:ucanaccess://%s;immediatelyReleaseResources=true", 
        dbFile.getAbsolutePath());
Connection conn = DriverManager.getConnection(connStr);

Read an Access database embedded in a JAR file

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