ScriptEngineManager.getEngineFactoriesreturns no factories on appengine

Question

The following code returns an empty array.

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

ScriptEngineManager manager = new ScriptEngineManager();
List<ScriptEngineFactory> factories = manager.getEngineFactories();

It works in the development environment, but not deployed.
Even after adding js.jar from rhino to the lib folder and adding it to the classpath, no EngineFactories are found.

What am I doing wrong?

I'm guessing you're using Rhino, but you don't say. You need to explicitly mention what library you're using, and show your imports. — Nick Johnson, Nov 23 '11 at 04:15
im running into the same issue. anyone had any luck with this? — Sam, Oct 15 '12 at 20:40
@Sam No. I ended up not using javax.script, and instead go directly to org.mozilla.javascript for the necessary APIs. See http://code.google.com/p/antonytrupe/source/browse/development/src/games/com/antonytrupe/games/server/GameEngine.java, http://code.google.com/p/antonytrupe/source/browse/development/src/diskwars/com/antonytrupe/server/diskwars/API.java, and related for examples — antony.trupe, Oct 16 '12 at 01:41

score 3 · Answer 1 · answered Nov 08 '13 at 00:34

GAE is a Java runtime very optimized. Even with the ScriptEngineManager is in the whitelist of supported classes, there is still one setting left, to make it work.

You need register the Rhino service, I have clues to archive it but not exactly. To register the service you must create the file 'META-INF/services/javax.script.ScriptEngineFactory' with one line with the exactly class name of a Rhino class that implements the 'ScriptEngineFactory' interface. And my problem is that I can't find these class.

If someone know please edit.

score 0 · Answer 2 · edited May 23 '17 at 12:13

0

Yes, Daniel is right, you'll need to use another JavaScript engine such as Rhino. I've put a possible solution on a similar question (which builds on a solution given by Harsha R): https://stackoverflow.com/a/28408123/578821

edited May 23 '17 at 12:13

Community

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answered Feb 09 '15 at 11:01

Ian

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ScriptEngineManager.getEngineFactoriesreturns no factories on appengine

2 Answers2