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Groovy: A powerful, dynamic language for the JVM
/*
* 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 groovy.util;
import groovy.lang.Binding;
import groovy.lang.GroovyClassLoader;
import groovy.lang.Script;
import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.codehaus.groovy.control.CompilationFailedException;
import org.codehaus.groovy.runtime.InvokerHelper;
/**
* Specific script engine able to reload modified scripts as well as dealing properly with dependent scripts.
*
* @author sam
* @author Marc Palmer
* @author Guillaume Laforge
*/
public class GroovyScriptEngine implements ResourceConnector {
/**
* Simple testing harness for the GSE. Enter script roots as arguments and
* then input script names to run them.
*
* @param urls an array of URLs
* @throws Exception if something goes wrong
*/
public static void main(String[] urls) throws Exception {
URL[] roots = new URL[urls.length];
for (int i = 0; i < roots.length; i++) {
if(urls[i].indexOf("://") != -1) {
roots[i] = new URL(urls[i]);
} else {
roots[i] = new File(urls[i]).toURI().toURL();
}
}
GroovyScriptEngine gse = new GroovyScriptEngine(roots);
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String line;
while (true) {
System.out.print("groovy> ");
if ((line = br.readLine()) == null || line.equals("quit"))
break;
try {
System.out.println(gse.run(line, new Binding()));
} catch (Exception e) {
e.printStackTrace();
}
}
}
private URL[] roots;
private Map scriptCache = Collections.synchronizedMap(new HashMap());
private ResourceConnector rc;
private static ThreadLocal currentCacheEntryHolder = new ThreadLocal();
private GroovyClassLoader groovyLoader = null;
private static class ScriptCacheEntry {
private Class scriptClass;
private long lastModified;
private Map dependencies = new HashMap();
}
/**
* Initialize a new GroovyClassLoader with the parentClassLoader passed as a parameter.
* A GroovyScriptEngine should only use one GroovyClassLoader but since in version
* prior to 1.0-RC-01 you could set a new parentClassLoader
* Ultimately groovyLoader should be final and only set in the constructor
*
* @param parentClassLoader the class loader to use
*/
private void initGroovyLoader(final ClassLoader parentClassLoader) {
if (groovyLoader == null || groovyLoader.getParent() != parentClassLoader) {
groovyLoader =
(GroovyClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
return new GroovyClassLoader(parentClassLoader) {
protected Class findClass(String className) throws ClassNotFoundException {
String filename = className.replace('.', File.separatorChar) + ".groovy";
URLConnection dependentScriptConn = null;
try {
dependentScriptConn = rc.getResourceConnection(filename);
ScriptCacheEntry currentCacheEntry = (ScriptCacheEntry) currentCacheEntryHolder.get();
currentCacheEntry.dependencies.put(
dependentScriptConn.getURL(),
new Long(dependentScriptConn.getLastModified()));
return parseClass(dependentScriptConn.getInputStream(), filename);
} catch (ResourceException e1) {
throw new ClassNotFoundException("Could not read " + className + ": " + e1);
} catch (CompilationFailedException e2) {
throw new ClassNotFoundException("Syntax error in " + className + ": " + e2);
} catch (IOException e3) {
throw new ClassNotFoundException("Problem reading " + className + ": " + e3);
} finally {
try {
if (dependentScriptConn != null && dependentScriptConn.getInputStream() != null) {
dependentScriptConn.getInputStream().close();
}
} catch (IOException e) {
// IGNORE
}
}
}
};
}
});
}
}
/**
* Get a resource connection as a URLConnection to retrieve a script
* from the ResourceConnector
*
* @param resourceName name of the resource to be retrieved
* @return a URLConnection to the resource
* @throws ResourceException
*/
public URLConnection getResourceConnection(String resourceName) throws ResourceException {
// Get the URLConnection
URLConnection groovyScriptConn = null;
ResourceException se = null;
for (int i = 0; i < roots.length; i++) {
URL scriptURL = null;
InputStream in = null;
try {
scriptURL = new URL(roots[i], resourceName);
groovyScriptConn = scriptURL.openConnection();
// Make sure we can open it, if we can't it doesn't exist.
// Could be very slow if there are any non-file:// URLs in there
in = groovyScriptConn.getInputStream();
break; // Now this is a bit unusual
} catch (MalformedURLException e) {
String message = "Malformed URL: " + roots[i] + ", " + resourceName;
if (se == null) {
se = new ResourceException(message);
} else {
se = new ResourceException(message, se);
}
} catch (IOException e1) {
String message = "Cannot open URL: " + scriptURL;
if (se == null) {
se = new ResourceException(message);
} else {
se = new ResourceException(message, se);
}
}
}
// If we didn't find anything, report on all the exceptions that occurred.
if (groovyScriptConn == null) {
throw se;
}
return groovyScriptConn;
}
/**
* The groovy script engine will run groovy scripts and reload them and
* their dependencies when they are modified. This is useful for embedding
* groovy in other containers like games and application servers.
*
* @param roots This an array of URLs where Groovy scripts will be stored. They should
* be layed out using their package structure like Java classes
*/
public GroovyScriptEngine(URL[] roots) {
this.roots = roots;
this.rc = this;
initGroovyLoader(getClass().getClassLoader());
}
public GroovyScriptEngine(URL[] roots, ClassLoader parentClassLoader) {
this(roots);
initGroovyLoader(parentClassLoader);
}
public GroovyScriptEngine(String[] urls) throws IOException {
roots = new URL[urls.length];
for (int i = 0; i < roots.length; i++) {
roots[i] = new File(urls[i]).toURI().toURL();
}
this.rc = this;
initGroovyLoader(getClass().getClassLoader());
}
public GroovyScriptEngine(String[] urls, ClassLoader parentClassLoader) throws IOException {
this(urls);
initGroovyLoader(parentClassLoader);
}
public GroovyScriptEngine(String url) throws IOException {
roots = new URL[1];
roots[0] = new File(url).toURI().toURL();
this.rc = this;
initGroovyLoader(getClass().getClassLoader());
}
public GroovyScriptEngine(String url, ClassLoader parentClassLoader) throws IOException {
this(url);
initGroovyLoader(parentClassLoader);
}
public GroovyScriptEngine(ResourceConnector rc) {
this.rc = rc;
initGroovyLoader(getClass().getClassLoader());
}
public GroovyScriptEngine(ResourceConnector rc, ClassLoader parentClassLoader) {
this(rc);
initGroovyLoader(parentClassLoader);
}
/**
* Get the ClassLoader that will serve as the parent ClassLoader of the
* {@link GroovyClassLoader} in which scripts will be executed. By default, this is the
* ClassLoader that loaded the GroovyScriptEngine class.
*
* @return parent classloader used to load scripts
*/
public ClassLoader getParentClassLoader() {
return groovyLoader.getParent();
}
/**
* @param parentClassLoader ClassLoader to be used as the parent ClassLoader for scripts executed by the engine
* @deprecated
*/
public void setParentClassLoader(ClassLoader parentClassLoader) {
if (parentClassLoader == null) {
throw new IllegalArgumentException("The parent class loader must not be null.");
}
initGroovyLoader(parentClassLoader);
}
/**
* Get the class of the scriptName in question, so that you can instantiate Groovy objects with caching and reloading.
*
* @param scriptName resource name pointing to the script
* @return the loaded scriptName as a compiled class
* @throws ResourceException if there is a problem accessing the script
* @throws ScriptException if there is a problem parsing the script
*/
public Class loadScriptByName(String scriptName) throws ResourceException, ScriptException {
scriptName = scriptName.replace('.', File.separatorChar) + ".groovy";
ScriptCacheEntry entry = updateCacheEntry(scriptName);
return entry.scriptClass;
}
/**
* Get the class of the scriptName in question, so that you can instantiate Groovy objects with caching and reloading.
*
* @param scriptName resource name pointing to the script
* @param parentClassLoader the class loader to use when loading the script
* @return the loaded scriptName as a compiled class
* @throws ResourceException if there is a problem accessing the script
* @throws ScriptException if there is a problem parsing the script
* @deprecated
*/
public Class loadScriptByName(String scriptName, ClassLoader parentClassLoader)
throws ResourceException, ScriptException {
initGroovyLoader(parentClassLoader);
return loadScriptByName(scriptName);
}
/**
* Locate the class and reload it or any of its dependencies
*
* @param scriptName resource name pointing to the script
* @return the cache entry for scriptName
* @throws ResourceException if there is a problem accessing the script
* @throws ScriptException if there is a problem parsing the script
*/
private ScriptCacheEntry updateCacheEntry(String scriptName)
throws ResourceException, ScriptException {
ScriptCacheEntry entry;
scriptName = scriptName.intern();
synchronized (scriptName) {
URLConnection groovyScriptConn = rc.getResourceConnection(scriptName);
// URL last modified
long lastModified = groovyScriptConn.getLastModified();
// Check the cache for the scriptName
entry = (ScriptCacheEntry) scriptCache.get(scriptName);
if (entry == null || entry.lastModified < lastModified || dependencyOutOfDate(entry)) {
// Make a new entry
ScriptCacheEntry currentCacheEntry = new ScriptCacheEntry();
currentCacheEntryHolder.set(currentCacheEntry);
InputStream in = null;
try {
in = groovyScriptConn.getInputStream();
currentCacheEntry.scriptClass = groovyLoader.parseClass(in, scriptName);
} catch (Exception e) {
throw new ScriptException("Could not parse scriptName: " + scriptName, e);
} finally {
currentCacheEntryHolder.set(null);
try {
if (in != null)
in.close();
} catch (IOException e) {
// Do nothing: Just want to make sure it is closed
}
}
currentCacheEntry.lastModified = lastModified;
scriptCache.put(scriptName, currentCacheEntry);
entry = currentCacheEntry;
currentCacheEntry = null;
}
}
return entry;
}
private boolean dependencyOutOfDate(ScriptCacheEntry entry) {
if (entry != null) {
for (Iterator i = entry.dependencies.keySet().iterator(); i.hasNext();) {
URLConnection urlc = null;
URL url = (URL) i.next();
try {
urlc = url.openConnection();
urlc.setDoInput(false);
urlc.setDoOutput(false);
long dependentLastModified = urlc.getLastModified();
if (dependentLastModified > ((Long) entry.dependencies.get(url)).longValue()) {
return true;
}
} catch (IOException ioe) {
return true;
}
}
}
return false;
}
/**
* Run a script identified by name with a single argument.
*
* @param scriptName name of the script to run
* @param argument a single argument passed as a variable named arg in the binding
* @return a toString() representation of the result of the execution of the script
* @throws ResourceException if there is a problem accessing the script
* @throws ScriptException if there is a problem parsing the script
*/
public String run(String scriptName, String argument) throws ResourceException, ScriptException {
Binding binding = new Binding();
binding.setVariable("arg", argument);
Object result = run(scriptName, binding);
return result == null ? "" : result.toString();
}
/**
* Run a script identified by name with a given binding.
*
* @param scriptName name of the script to run
* @param binding binding to pass to the script
* @return an object
* @throws ResourceException if there is a problem accessing the script
* @throws ScriptException if there is a problem parsing the script
*/
public Object run(String scriptName, Binding binding) throws ResourceException, ScriptException {
ScriptCacheEntry entry = updateCacheEntry(scriptName);
Script scriptObject = createScript(binding, entry);
return scriptObject.run();
}
/**
* Creates a Script object given a cache entry object and a binding.
*
* @param binding the binding to use
* @param entry the script cache entry
* @return the script object
*/
public Script createScript(Binding binding, ScriptCacheEntry entry) {
return InvokerHelper.createScript(entry.scriptClass, binding);
}
}