Berkeley DB Reference Guide: Java API

Configuration

Building the Berkeley DB java classes, the examples and the native support library is integrated into the normal build process. See Configuring Berkeley DB and Building for Windows for more information.

We expect that you've already installed the Java JDK or equivalent on your system. For the sake of discussion, we'll assume it is in a directory called db-VERSION, e.g., you extracted Berkeley DB version 2.3.12 and you did not change the top-level directory name. The files related to Java are in two subdirectories of db-VERSION: java, the java source files, and libdb_java, the C++ files that provide the "glue" between java and Berkeley DB. The directory tree looks like this:

		db-VERSION
	       /          \
	    java        libdb_java
	     |              |
	    src            ...
	     |
	    com
	     |
	 sleepycat
	/         \
       db       examples
       |           |
      ...         ...

This naming conforms to the emerging standard for naming java packages. When the java code is built, it is placed into a classes subdirectory that is parallel to the src subdirectory.

For your application to use Berkeley DB successfully, you must set your CLASSPATH environment variable to include db-VERSION/java/classes as well as the classes in your java distribution. On UNIX, CLASSPATH is a colon separated list of directories; on Windows it is separated by semicolons. Alternatively, you can set your CLASSPATH to include db-VERSION/java/classes/db.jar which is created as a result of the build. The db.jar file contains the classes in com.sleepycat.db, it does not contain any classes in com.sleepycat.examples.

On Windows, you will want to set your PATH variable to include:

db-VERSION\build_win32\Release

On UNIX, you will want to set the LD_LIBRARY_PATH environment variable to include the Berkeley DB library installation directory. Of course, the standard install directory may have been changed for your site, see your system administrator for details. Regardless, if you get a:

java.lang.UnsatisfiedLinkError

exception when you run, chances are you do not have the library search path configured correctly. Different Java interpreters provide different error messages if the CLASSPATH value is incorrect, a typical error is:

java.lang.NoClassDefFoundError

To ensure that everything is running correctly, you may want to try a simple test from the example programs in:

db-VERSION/java/src/com/sleepycat/examples

For example, the sample program:

% java com.sleepycat.examples.AccessExample

will prompt for text input lines which are then stored in a Btree database named "access.db" in your current directory. Try giving it a few lines of input text and then end-of-file. Before it exits, you should see a list of the lines you entered display with data items. This is a simple check to make sure the fundamental configuration is working correctly.

Copyright Sleepycat Software