Java tutorial
/* * Copyright 1999-2004 The Apache Software Foundation. * * 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.apache.cocoon.components.flow.java; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import org.apache.avalon.framework.configuration.Configurable; import org.apache.avalon.framework.configuration.Configuration; import org.apache.avalon.framework.configuration.ConfigurationException; import org.apache.avalon.framework.parameters.Parameters; import org.apache.cocoon.ProcessingException; import org.apache.cocoon.components.ContextHelper; import org.apache.cocoon.components.flow.AbstractInterpreter; import org.apache.cocoon.components.flow.FlowHelper; import org.apache.cocoon.components.flow.InvalidContinuationException; import org.apache.cocoon.components.flow.WebContinuation; import org.apache.cocoon.environment.Redirector; import org.apache.cocoon.environment.Request; import org.apache.cocoon.environment.Session; import org.apache.cocoon.util.ReflectionUtils; import org.apache.commons.jxpath.JXPathIntrospector; /** * Implementation of the java flow interpreter. * * @author <a href="mailto:stephan@apache.org">Stephan Michels</a> * @version CVS $Id: JavaInterpreter.java 170618 2005-05-17 17:10:22Z gregor $ */ public class JavaInterpreter extends AbstractInterpreter implements Configurable { private boolean initialized = false; private int timeToLive = 600000; /** * Key for storing a global scope object in the Cocoon session */ public static final String USER_GLOBAL_SCOPE = "JAVA GLOBAL SCOPE"; private ClassLoader classloader; private Map methods = new HashMap(); static { JXPathIntrospector.registerDynamicClass(VarMap.class, VarMapHandler.class); } public void configure(Configuration config) throws ConfigurationException { super.configure(config); } public synchronized void initialize() throws Exception { if (initialized) { return; } try { if (getLogger().isDebugEnabled()) getLogger().debug("initialize java flow interpreter"); classloader = new ContinuationClassLoader(Thread.currentThread().getContextClassLoader()); for (Iterator scripts = needResolve.iterator(); scripts.hasNext();) { String classname = (String) scripts.next(); if (getLogger().isDebugEnabled()) getLogger().debug("registered java class \"" + classname + "\" for flow"); if (!Continuable.class.isAssignableFrom(Class.forName(classname))) { getLogger().error("java class \"" + classname + "\" doesn't implement Continuable"); continue; } Class clazz = classloader.loadClass(classname); final Map m = ReflectionUtils.discoverMethods(clazz); methods.putAll(m); //Only initialize if everything so far hasn't thrown any exceptions. initialized = true; } } catch (final Exception e) { throw new ConfigurationException("Cannot initialize JavaInterpreter", e); } } /** * Calls a Java function, passing <code>params</code> as its * arguments. In addition to this, it makes available the parameters * through the <code>cocoon.parameters</code> Java array * (indexed by the parameter names). * * @param function a <code>String</code> value * @param params a <code>List</code> value * @param redirector * @exception Exception if an error occurs */ public void callFunction(String function, List params, Redirector redirector) throws Exception { if (!initialized) initialize(); Method method = (Method) methods.get(function); if (method == null) { throw new ProcessingException("No method '" + function + "' found. " + methods); } if (getLogger().isDebugEnabled()) getLogger().debug("calling method \"" + method + "\""); Request request = ContextHelper.getRequest(this.avalonContext); Session session = request.getSession(true); HashMap userScopes = (HashMap) session.getAttribute(USER_GLOBAL_SCOPE); if (userScopes == null) userScopes = new HashMap(); Continuable flow = (Continuable) userScopes.get(method.getDeclaringClass()); ContinuationContext context = new ContinuationContext(); context.setObject(flow); context.setMethod(method); context.setAvalonContext(avalonContext); context.setLogger(getLogger()); context.setServiceManager(manager); context.setRedirector(redirector); Parameters parameters = new Parameters(); for (Iterator i = params.iterator(); i.hasNext();) { Argument argument = (Argument) i.next(); parameters.setParameter(argument.name, argument.value); } context.setParameters(parameters); Continuation continuation = new Continuation(context); WebContinuation wk = continuationsMgr.createWebContinuation(continuation, null, timeToLive, getInterpreterID(), null); FlowHelper.setWebContinuation(ContextHelper.getObjectModel(this.avalonContext), wk); continuation.registerThread(); try { if (flow == null) { if (getLogger().isDebugEnabled()) getLogger().debug("create new instance of \"" + method.getDeclaringClass() + "\""); flow = (Continuable) method.getDeclaringClass().newInstance(); context.setObject(flow); } method.invoke(flow, new Object[0]); } catch (InvocationTargetException ite) { if (ite.getTargetException() != null) { if (ite.getTargetException() instanceof Exception) throw (Exception) ite.getTargetException(); else if (ite.getTargetException() instanceof Error) throw new ProcessingException("An internal error occured", ite.getTargetException()); else if (ite.getTargetException() instanceof RuntimeException) throw (RuntimeException) ite.getTargetException(); else throw ite; } else { throw ite; } } finally { // remove last object reference, which is not needed to // reconstruct the invocation path if (continuation.isCapturing()) continuation.getStack().popReference(); continuation.deregisterThread(); } userScopes.put(method.getDeclaringClass(), flow); session.setAttribute(USER_GLOBAL_SCOPE, userScopes); } public void handleContinuation(String id, List params, Redirector redirector) throws Exception { if (!initialized) initialize(); WebContinuation parentwk = continuationsMgr.lookupWebContinuation(id, getInterpreterID()); if (parentwk == null) { /* * Throw an InvalidContinuationException to be handled inside the * <map:handle-errors> sitemap element. */ throw new InvalidContinuationException("The continuation ID " + id + " is invalid."); } Continuation parentContinuation = (Continuation) parentwk.getContinuation(); ContinuationContext parentContext = (ContinuationContext) parentContinuation.getContext(); ContinuationContext context = new ContinuationContext(); context.setObject(parentContext.getObject()); context.setMethod(parentContext.getMethod()); context.setAvalonContext(avalonContext); context.setLogger(getLogger()); context.setServiceManager(manager); context.setRedirector(redirector); Parameters parameters = new Parameters(); for (Iterator i = params.iterator(); i.hasNext();) { Argument argument = (Argument) i.next(); parameters.setParameter(argument.name, argument.value); } context.setParameters(parameters); Continuation continuation = new Continuation(parentContinuation, context); Request request = ContextHelper.getRequest(this.avalonContext); Session session = request.getSession(true); HashMap userScopes = (HashMap) session.getAttribute(USER_GLOBAL_SCOPE); Continuable flow = (Continuable) context.getObject(); Method method = context.getMethod(); WebContinuation wk = continuationsMgr.createWebContinuation(continuation, parentwk, timeToLive, getInterpreterID(), null); FlowHelper.setWebContinuation(ContextHelper.getObjectModel(this.avalonContext), wk); continuation.registerThread(); try { method.invoke(flow, new Object[0]); } catch (InvocationTargetException ite) { if (ite.getTargetException() != null) { if (ite.getTargetException() instanceof Exception) throw (Exception) ite.getTargetException(); else if (ite.getTargetException() instanceof Error) throw new ProcessingException("An internal error occured", ite.getTargetException()); else if (ite.getTargetException() instanceof RuntimeException) throw (RuntimeException) ite.getTargetException(); else throw ite; } else { throw ite; } } finally { // remove last object reference, which is not needed to reconstruct // the invocation path if (continuation.isCapturing()) continuation.getStack().popReference(); continuation.deregisterThread(); } userScopes.put(method.getDeclaringClass(), flow); session.setAttribute(USER_GLOBAL_SCOPE, userScopes); } }