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Groovy example source code file (CachingGroovyEngine.java)

This example Groovy source code file (CachingGroovyEngine.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 - Groovy tags/keywords

bsfexception, bsfexception, class, class, classloader, compilerconfiguration, groovy, groovyclassloader, groovyclassloader, hashmap, log, logging, map, object, object, security, string, util

The Groovy CachingGroovyEngine.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * 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.codehaus.groovy.bsf;

import groovy.lang.Binding;
import groovy.lang.GroovyClassLoader;
import groovy.lang.GroovyShell;
import groovy.lang.Script;
import org.apache.bsf.BSFDeclaredBean;
import org.apache.bsf.BSFException;
import org.apache.bsf.BSFManager;
import org.apache.bsf.util.BSFFunctions;
import org.codehaus.groovy.control.CompilerConfiguration;
import org.codehaus.groovy.runtime.InvokerHelper;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.HashMap;
import java.util.Map;
import java.util.Vector;
import java.util.logging.Logger;
import java.util.logging.Level;

/**
 * A Caching implementation of the GroovyEngine
 *
 * @author James Birchfield
 */
public class CachingGroovyEngine extends GroovyEngine {
    private static final Logger LOG = Logger.getLogger(CachingGroovyEngine.class.getName());
    private static final Object[] EMPTY_ARGS = new Object[]{new String[]{}};

    private Map evalScripts;
    private Map execScripts;
    private Binding context;
    private GroovyClassLoader loader;

    /**
     * Evaluate an expression.
     */
    public Object eval(String source, int lineNo, int columnNo, Object script) throws BSFException {
        try {
            Class scriptClass = (Class) evalScripts.get(script);
            if (scriptClass == null) {
                scriptClass = loader.parseClass(script.toString(), source);
                evalScripts.put(script, scriptClass);
            } else {
                LOG.fine("eval() - Using cached script...");
            }
            //can't cache the script because the context may be different.
            //but don't bother loading parsing the class again
            Script s = InvokerHelper.createScript(scriptClass, context);
            return s.run();
        } catch (Exception e) {
            throw new BSFException(BSFException.REASON_EXECUTION_ERROR, "exception from Groovy: " + e, e);
        }
    }

    /**
     * Execute a script.
     */
    public void exec(String source, int lineNo, int columnNo, Object script) throws BSFException {
        try {
            //          shell.run(script.toString(), source, EMPTY_ARGS);

            Class scriptClass = (Class) execScripts.get(script);
            if (scriptClass == null) {
                scriptClass = loader.parseClass(script.toString(), source);
                execScripts.put(script, scriptClass);
            } else {
                LOG.fine("exec() - Using cached version of class...");
            }
            InvokerHelper.invokeMethod(scriptClass, "main", EMPTY_ARGS);
        } catch (Exception e) {
            LOG.log(Level.WARNING, "BSF trace", e);
            throw new BSFException(BSFException.REASON_EXECUTION_ERROR, "exception from Groovy: " + e, e);
        }
    }

    /**
     * Initialize the engine.
     */
    public void initialize(final BSFManager mgr, String lang, Vector declaredBeans) throws BSFException {
        super.initialize(mgr, lang, declaredBeans);
        ClassLoader parent = mgr.getClassLoader();
        if (parent == null)
            parent = GroovyShell.class.getClassLoader();
        final ClassLoader finalParent = parent;
        this.loader =
                (GroovyClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
                    public Object run() {
                        CompilerConfiguration configuration = new CompilerConfiguration();
                        configuration.setClasspath(mgr.getClassPath());
                        return new GroovyClassLoader(finalParent, configuration);
                    }
                });
        execScripts = new HashMap();
        evalScripts = new HashMap();
        context = shell.getContext();
        // create a shell
        // register the mgr with object name "bsf"
        context.setVariable("bsf", new BSFFunctions(mgr, this));
        int size = declaredBeans.size();
        for (int i = 0; i < size; i++) {
            declareBean((BSFDeclaredBean) declaredBeans.elementAt(i));
        }
    }
}

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