org.hibernate.validator.internal.util.scriptengine.ScriptEvaluator Maven / Gradle / Ivy
/*
* JBoss, Home of Professional Open Source
* Copyright 2010, Red Hat, Inc. and/or its affiliates, and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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.
*/
package org.hibernate.validator.internal.util.scriptengine;
import javax.script.ScriptEngine;
import javax.script.ScriptException;
/**
* A wrapper around JSR 223 {@link ScriptEngine}s. This class is thread-safe.
*
* @author Gunnar Morling
* @author Kevin Pollet (C) 2011 SERLI
*/
public class ScriptEvaluator {
private final ScriptEngine engine;
/**
* Creates a new script executor.
*
* @param engine The engine to be wrapped.
*/
public ScriptEvaluator(ScriptEngine engine) {
this.engine = engine;
}
/**
* Makes the given object available in then engine-scoped script context and executes the given script.
* The execution of the script happens either synchronized or unsynchronized, depending on the engine's
* threading abilities.
*
* @param script The script to be executed.
* @param obj The object to be put into the context.
* @param objectAlias The name under which the given object shall be put into the context.
*
* @return The script's result.
*
* @throws ScriptException In case of any errors during script execution.
*/
public Object evaluate(String script, Object obj, String objectAlias) throws ScriptException {
if ( engineAllowsParallelAccessFromMultipleThreads() ) {
return doEvaluate( script, obj, objectAlias );
}
else {
synchronized ( engine ) {
return doEvaluate( script, obj, objectAlias );
}
}
}
private Object doEvaluate(String script, Object obj, String objectAlias) throws ScriptException {
engine.put( objectAlias, obj );
return engine.eval( script );
}
/**
* Checks, whether the given engine is thread-safe or not.
*
* @return True, if the given engine is thread-safe, false otherwise.
*/
private boolean engineAllowsParallelAccessFromMultipleThreads() {
String threadingType = (String) engine.getFactory().getParameter( "THREADING" );
return "THREAD-ISOLATED".equals( threadingType ) || "STATELESS".equals( threadingType );
}
}