Ant example source code file (JavaxScriptRunner.java)

This example Ant source code file (JavaxScriptRunner.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

buildexception, buildexception, classloader, exception, iterator, javaxscriptrunner, object, object, reflectwrapper, reflectwrapper, string, string, throwable, unable, util

The JavaxScriptRunner.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.tools.ant.util.optional;

import org.apache.tools.ant.BuildException;


import java.util.Iterator;
import org.apache.tools.ant.util.ScriptRunnerBase;
import org.apache.tools.ant.util.ReflectUtil;
import org.apache.tools.ant.util.ReflectWrapper;

/**
 * This class is used to run scripts using JSR 223.
 * @since Ant 1.7.0
 */
public class JavaxScriptRunner extends ScriptRunnerBase {
    private ReflectWrapper engine;

    /**
     * Get the name of the manager prefix.
     * @return "javax"
     */
    public String getManagerName() {
        return "javax";
    }

    /** {@inheritDoc}. */
    public boolean supportsLanguage() {
        if (engine != null) {
            return true;
        }
        checkLanguage();
        ClassLoader origLoader = replaceContextLoader();
        try {
            return createEngine() != null;
        } catch (Exception ex) {
            return false;
        } finally {
            restoreContextLoader(origLoader);
        }
    }

    /**
     * Do the work to run the script.
     *
     * @param execName the name that will be passed to the
     *                 scripting engine for this script execution.
     *
     * @exception BuildException if someting goes wrong exectuing the script.
     */
    public void executeScript(String execName) throws BuildException {
        evaluateScript(execName);
    }

    /**
     * Do the work to eval the script.
     *
     * @param execName the name that will be passed to the
     *                 scripting engine for this script execution.
     * @return the result of the evalulation
     * @exception BuildException if someting goes wrong exectuing the script.
     */
    public Object evaluateScript(String execName) throws BuildException {
        checkLanguage();
        ClassLoader origLoader = replaceContextLoader();
        try {
            ReflectWrapper engine = createEngine();
            if (engine == null) {
                throw new BuildException(
                    "Unable to create javax script engine for "
                    + getLanguage());
            }
            for (Iterator i = getBeans().keySet().iterator(); i.hasNext();) {
                String key = (String) i.next();
                Object value = getBeans().get(key);
                engine.invoke(
                    "put", String.class, key, Object.class, value);
            }
            // execute the script
            return engine.invoke("eval", String.class, getScript());
        } catch (Exception be) {
            Throwable t = be;
            Throwable te = (Throwable) ReflectUtil.invoke(be, "getCause");
            if (te != null) {
                if  (te instanceof BuildException) {
                    throw (BuildException) te;
                } else {
                    t = te;
                }
            }
            throw new BuildException(t);
        } finally {
            restoreContextLoader(origLoader);
        }
    }

    private ReflectWrapper createEngine() throws Exception {
        if (engine != null) {
            return engine;
        }
        ReflectWrapper manager = new ReflectWrapper(
            getClass().getClassLoader(), "javax.script.ScriptEngineManager");
        Object e = manager.invoke(
            "getEngineByName", String.class, getLanguage());
        if (e == null) {
            return null;
        }
        ReflectWrapper ret = new ReflectWrapper(e);
        if (getKeepEngine()) {
            this.engine = ret;
        }
        return ret;
    }
}