Is it possible to import javascript files to a java ScriptEngine

Question

I am using nashorn java ScriptEngine. I would like to evaluate a script which includes other scripts. I know I can use the load directive directly in the javascript itself, but I would prefer to import or load it directly from the java code instanciating the scriptEngine. Is there a way to do this ? Something like :

void evaluateScript(String scriptName, String dependency) {
    ScriptEngineManager factory = new ScriptEngineManager();
    ScriptEngine jsEngine = factory.getEngineByName("nashorn");
    jsEngine.load(depency); // does not exist.
    jsEngine.eval();
}

I see the "load" function does not exist. How could I achieve this?

Thanks

Joel · Accepted Answer · 2017-07-16 09:39:29Z

Actually I found the answer myself: as mentioned in the comment, it is possible to call several eval with different scripts, same engine, and the engine will keep the evaluated scripts in its context. So here is my code:

public void executeScript(String scriptName, String[] dependencies) {
    try {
        FileReader script = new FileReader(scriptName);
        ScriptEngineManager factory = new ScriptEngineManager();
        ScriptEngine jsEngine = factory.getEngineByName("nashorn");

        if(dependencies != null) {
            for (String dependency : dependencies) {
                FileReader dependencyFile = new FileReader(dependency);
                jsEngine.eval(dependencyFile);
            }
        }

        jsEngine.eval(script);
    }
}

I can define functions in my dependencies and use them in the script of name scriptName.

A. Sundararajan · Accepted Answer · 2017-07-15 14:05:09Z

0

javax.script.ScriptEngine has many "eval" methods - there are java.io.Reader accepting eval methods like this -> eval

You can pass a java.io.FileReader or a jdk.nashorn.api.scripting.URLReader to load script from a file or a URL.

answered Jul 15, 2017 at 14:05

A. Sundararajan

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2 Comments

Joel Over a year ago

Hello, thanks for the answer but it does not fit my question: I want to execute one script theScript, together with other scripts otherScriptList. But I will try eval on different scripts with the same engine and check if the engine keeps the previous ones in his context.

A. Sundararajan Over a year ago

Yes, same engine keeps "context"!

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