de.ingrid.iplug.ckan.utils.ScriptEngine.java Source code

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Here is the source code for de.ingrid.iplug.ckan.utils.ScriptEngine.java

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/*
 * **************************************************-
 * InGrid-iPlug CKAN
 * ==================================================
 * Copyright (C) 2014 - 2016 wemove digital solutions GmbH
 * ==================================================
 * Licensed under the EUPL, Version 1.1 or  as soon they will be
 * approved by the European Commission - subsequent versions of the
 * EUPL (the "Licence");
 * 
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * 
 * http://ec.europa.eu/idabc/eupl5
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 * **************************************************#
 */
package de.ingrid.iplug.ckan.utils;

import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Hashtable;
import java.util.Map;

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

import org.springframework.core.io.Resource;

/**
 * This class allows to execute scripts
 * @author ingo@wemove.com
 */
public class ScriptEngine {

    protected static ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
    protected static Map<String, javax.script.ScriptEngine> engines = new Hashtable<String, javax.script.ScriptEngine>();
    protected static Map<String, CompiledScript> compiledScripts = new Hashtable<String, CompiledScript>();

    /**
     * Execute the given scripts with the given parameters
     * @param scripts The script files
     * @param parameters The parameters
     * @param compile Boolean indicating whether to compile the script or not
     * @return Map with the absolute paths of the scripts as keys and the execution results as values
     * If an execution returns null, the result will not be added
     * @throws Exception
     */
    public static Map<String, Object> execute(Resource[] scripts, Map<String, Object> parameters, boolean compile)
            throws Exception {

        Map<Integer, Bindings> bindings = new Hashtable<Integer, Bindings>();
        Map<String, Object> results = new Hashtable<String, Object>();

        for (Resource script : scripts) {
            // get the engine for the script
            javax.script.ScriptEngine engine = getEngine(script);

            // initialize/get the bindings
            if (!bindings.containsKey(engine.hashCode())) {
                Bindings newBindings = engine.createBindings();
                newBindings.putAll(parameters);
                bindings.put(engine.hashCode(), newBindings);
            }
            Bindings curBindings = bindings.get(engine.hashCode());

            // execute the script
            CompiledScript compiledScript = null;
            Object result = null;
            if (compile && (compiledScript = getCompiledScript(script)) != null) {
                result = compiledScript.eval(curBindings);
            } else {
                result = engine.eval(new InputStreamReader(script.getInputStream()), curBindings);
            }
            if (result != null) {
                results.put(script.getFilename(), result);
            }
        }
        return results;
    }

    /**
     * Get the compiled version of the given script
     * @param script The script file
     * @return CompiledScript
     * @throws ScriptException
     * @throws IOException 
     */
    protected static CompiledScript getCompiledScript(Resource script) throws ScriptException, IOException {
        String filename = script.getFilename();
        if (!compiledScripts.containsKey(filename)) {
            javax.script.ScriptEngine engine = getEngine(script);
            if (engine instanceof Compilable) {
                Compilable compilable = (Compilable) engine;
                CompiledScript compiledScript = compilable.compile(new InputStreamReader(script.getInputStream()));
                compiledScripts.put(filename, compiledScript);
            }
        }
        return compiledScripts.get(filename);
    }

    /**
     * Get the scripting engine for the given script file
     * @param script The script file
     * @return javax.script.ScriptEngine
     */
    protected static javax.script.ScriptEngine getEngine(Resource script) {
        String scriptName = script.getFilename();
        String extension = scriptName.substring(scriptName.lastIndexOf('.') + 1, scriptName.length());
        if (!engines.containsKey(extension)) {
            javax.script.ScriptEngine engine = scriptEngineManager.getEngineByExtension(extension);
            engines.put(extension, engine);
        }
        return engines.get(extension);
    }
}