Java tutorial
/* * Copyright 2010 JBoss Inc * * 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.drools.eclipse.debug; import org.drools.eclipse.DroolsEclipsePlugin; import org.eclipse.core.resources.IResource; import org.eclipse.core.runtime.CoreException; import org.eclipse.core.runtime.IAdaptable; import org.eclipse.core.runtime.IStatus; import org.eclipse.core.runtime.Status; import org.eclipse.debug.core.DebugEvent; import org.eclipse.debug.core.DebugException; import org.eclipse.debug.core.DebugPlugin; import org.eclipse.debug.core.IStatusHandler; import org.eclipse.debug.core.model.IDebugTarget; import org.eclipse.debug.core.model.ISourceLocator; import org.eclipse.debug.core.model.IThread; import org.eclipse.debug.core.model.IValue; import org.eclipse.debug.core.sourcelookup.ISourceLookupDirector; import org.eclipse.jdt.core.IJavaElement; import org.eclipse.jdt.core.IJavaProject; import org.eclipse.jdt.core.JavaCore; import org.eclipse.jdt.debug.core.IJavaClassType; import org.eclipse.jdt.debug.core.IJavaDebugTarget; import org.eclipse.jdt.debug.core.IJavaObject; import org.eclipse.jdt.debug.core.IJavaReferenceType; import org.eclipse.jdt.debug.core.IJavaStackFrame; import org.eclipse.jdt.debug.core.IJavaThread; import org.eclipse.jdt.debug.core.IJavaType; import org.eclipse.jdt.debug.core.IJavaValue; import org.eclipse.jdt.debug.eval.IAstEvaluationEngine; import org.eclipse.jdt.debug.eval.ICompiledExpression; import org.eclipse.jdt.debug.eval.IEvaluationListener; import org.eclipse.jdt.debug.eval.IEvaluationResult; import org.eclipse.jdt.internal.debug.core.JDIDebugPlugin; public class DebugUtil { public static final int INFO_EVALUATION_STACK_FRAME = 111; private static IStatus fgNeedStackFrame = new Status(IStatus.INFO, DroolsEclipsePlugin.getUniqueIdentifier(), INFO_EVALUATION_STACK_FRAME, "Provides thread context for an evaluation", null); private static IStatusHandler fgStackFrameProvider; public static IValue getValueByExpression(String expression, IValue value) { if (!(value instanceof IJavaObject)) { return null; } IJavaObject javaValue = (IJavaObject) value; try { IJavaType type = javaValue.getJavaType(); if (!(type instanceof IJavaClassType)) { return null; } IJavaStackFrame stackFrame = getStackFrame(javaValue); if (stackFrame == null) { return null; } // find the project the snippets will be compiled in. ISourceLocator locator = javaValue.getLaunch().getSourceLocator(); Object sourceElement = null; if (locator instanceof ISourceLookupDirector) { String[] sourcePaths = ((IJavaClassType) type).getSourcePaths(null); if (sourcePaths != null && sourcePaths.length > 0) { sourceElement = ((ISourceLookupDirector) locator).getSourceElement(sourcePaths[0]); } if (!(sourceElement instanceof IJavaElement) && sourceElement instanceof IAdaptable) { sourceElement = ((IAdaptable) sourceElement).getAdapter(IJavaElement.class); } } if (sourceElement == null) { sourceElement = locator.getSourceElement(stackFrame); if (!(sourceElement instanceof IJavaElement) && sourceElement instanceof IAdaptable) { Object newSourceElement = ((IAdaptable) sourceElement).getAdapter(IJavaElement.class); // if the source is a drl during the execution of the rule if (newSourceElement != null) { sourceElement = newSourceElement; } } } IJavaProject project = null; if (sourceElement instanceof IJavaElement) { project = ((IJavaElement) sourceElement).getJavaProject(); } else if (sourceElement instanceof IResource) { IJavaProject resourceProject = JavaCore.create(((IResource) sourceElement).getProject()); if (resourceProject.exists()) { project = resourceProject; } } if (project == null) { return null; } IAstEvaluationEngine evaluationEngine = JDIDebugPlugin.getDefault().getEvaluationEngine(project, (IJavaDebugTarget) stackFrame.getDebugTarget()); EvaluationBlock evaluationBlock = new EvaluationBlock(javaValue, (IJavaReferenceType) type, (IJavaThread) stackFrame.getThread(), evaluationEngine); return evaluationBlock.evaluate(expression); } catch (CoreException e) { DroolsEclipsePlugin.log(e); } return null; } /** * Return the current stack frame context, or a valid stack frame for the * given value. */ public static IJavaStackFrame getStackFrame(IValue value) throws CoreException { IStatusHandler handler = getStackFrameProvider(); if (handler != null) { IJavaStackFrame stackFrame = (IJavaStackFrame) handler.handleStatus(fgNeedStackFrame, value); if (stackFrame != null) { return stackFrame; } } IDebugTarget target = value.getDebugTarget(); IJavaDebugTarget javaTarget = (IJavaDebugTarget) target.getAdapter(IJavaDebugTarget.class); if (javaTarget != null) { IThread[] threads = javaTarget.getThreads(); for (int i = 0; i < threads.length; i++) { IThread thread = threads[i]; if (thread.isSuspended()) { return (IJavaStackFrame) thread.getTopStackFrame(); } } } return null; } private static IStatusHandler getStackFrameProvider() { if (fgStackFrameProvider == null) { fgStackFrameProvider = DebugPlugin.getDefault().getStatusHandler(fgNeedStackFrame); } return fgStackFrameProvider; } private static class EvaluationBlock implements IEvaluationListener { private IJavaObject fEvaluationValue; private IJavaReferenceType fEvaluationType; private volatile IJavaThread fThread; private IAstEvaluationEngine fEvaluationEngine; private volatile IEvaluationResult fResult; public EvaluationBlock(IJavaObject value, IJavaReferenceType type, IJavaThread thread, IAstEvaluationEngine evaluationEngine) { fEvaluationValue = value; fEvaluationType = type; fThread = thread; fEvaluationEngine = evaluationEngine; } public void evaluationComplete(IEvaluationResult result) { synchronized (fThread) { fResult = result; fThread.notifyAll(); } } public IJavaValue evaluate(String snippet) throws DebugException { ICompiledExpression compiledExpression = fEvaluationEngine.getCompiledExpression(snippet, fEvaluationType); if (compiledExpression.hasErrors()) { String[] errorMessages = compiledExpression.getErrorMessages(); String message = ""; for (int i = 0; i < errorMessages.length; i++) { message += errorMessages[i] + "\n"; } throw new DebugException( new Status(IStatus.ERROR, DroolsEclipsePlugin.PLUGIN_ID, DroolsEclipsePlugin.INTERNAL_ERROR, "Error when compiling snippet " + snippet + ": " + message, null)); } fResult = null; fEvaluationEngine.evaluateExpression(compiledExpression, fEvaluationValue, fThread, this, DebugEvent.EVALUATION_IMPLICIT, false); synchronized (fThread) { while (fResult == null) { try { fThread.wait(100); } catch (InterruptedException e) { } } } if (fResult == null) { return null; } if (fResult.hasErrors()) { return null; } return fResult.getValue(); } } }