classpath-manager: Nailgun add-on to run Java classes with configurable classpath

by Stuart Sierra, http://stuartsierra.com/

Copyright (C) 2010 Stuart Sierra.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Step One: Compile classpath-manager

You will need Maven version 2.0 or later.

Run mvn package in this directory.

The JAR file will be created at target/classpath-manager-$VERSION.jar where $VERSION is the current version of classpath-manager.

Step Two: Install Nailgun

Download Nailgun.

Compile the Nailgun command-line client.

Copy the ng executable to your PATH.

Step Three: Run Nailgun

Run a Nailgun server like this:

java -jar /your/path/to/nailgun-0.7.1.jar

Add the classpath-manager JAR to the Nailgun classpath:

ng ng-cp /your/path/to/classpath-manager-$VERSION.jar

where $VERSION is the current version of classpath-manager. The path to the JAR must be an absolute path.

Add a short alias cm for the ClasspathManager main class:

ng ng-alias cm com.stuartsierra.ClasspathManager

Step Four: Create a classpath File

Create a text file named classpath in a project directory.

On each line of the file, put the name of a directory or JAR file to be included in the classpath for that project. For example:

src
test
classes
lib/library.jar

Paths will be interpreted as relative to the project directory unless they begin with a "/".

Shell wildcards are not supported.

Step Five: Run classpath-manager

Run ng cm your-main-class in your project directory to run your-main-class with the configured classpath.

Example:

 ng cm clojure.main

Caveats

• Static class fields are shared among all applications. For Clojure, this means you have one global Clojure runtime.

• Your main class runs in the same working directory as the Nailgun server process.

• Your main class runs as the same user as the Nailgun server process.

• The Java System properties user.dir and java.class.path are not useful.

ChangeLog

2010-07-06 v1.1.0

• Cache classloaders by URL in between invocations

2010-07-05 v1.0.0

• Initial release