Execution of Groovy code in java at runtime

Question

Is it possible to execute groovy code dynamically loaded in java application. For example there is a database table which contains small pieces of groovy code, like:

def test(${val_to_insert_from_java}){
    if (${val_to_insert_from_java} > 10){
        return true;
    }
    return false;
}

Where ${val_to_insert_from_java} is a placeholder for some real value which gonna be inserted during execution of java code, like:

String groovyFuncSource = getFromDb();
groovyFuncSource.replace(${val_to_insert_from_java}, 9);
Object result = <evaluate somehow groovyFuncSource>;

Is there is a way to evaluate such piece of Groovy code? Or may be you advise me some other approach how to implemnt this.

Answer 1

Yes, you can do this.

See the link http://groovy.codehaus.org/Embedding+Groovy

You may want to use caution with this approach, because executing code stored in a database will introduce security flaws in your application. For example, some code maliciously inserted as text in your database could do ... almost anything unless you're checking it.

Answer 2

An alternative would be to use JavaScript instead of Groovy. Why? Because the Rhino JavaScript engine already comes with the JDK . So if you aren't already using Groovy in your projects, it's one less dependency.

Answer 3

From Java 6 you can use Java Scripting API to do that. Java scripting API allows you to use various scripting languages within Java apps.

You can find more about Java Scripting here .

Answer 4

Yes, you can use the Groovy script engine to evaluate Groovy source code at execution time - and of course that source code can be the result of string replacements.

From what I remember, there are various ways you can accomplish this, which will have different pros and cons.

<plug> See chapter 11 of Groovy in Action for more details. </plug>