Java tutorial
/* * 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.wicket.markup.html.pages; import java.util.List; import javax.servlet.http.HttpServletResponse; import org.apache.wicket.Page; import org.apache.wicket.WicketRuntimeException; import org.apache.wicket.markup.MarkupException; import org.apache.wicket.markup.MarkupStream; import org.apache.wicket.markup.html.WebMarkupContainer; import org.apache.wicket.markup.html.basic.Label; import org.apache.wicket.markup.html.basic.MultiLineLabel; import org.apache.wicket.markup.html.debug.PageView; import org.apache.wicket.markup.html.link.Link; import org.apache.wicket.request.http.WebResponse; import org.apache.wicket.util.lang.Generics; /** * Shows a runtime exception on a nice HTML page. * * @author Jonathan Locke */ public class ExceptionErrorPage extends AbstractErrorPage { private static final long serialVersionUID = 1L; /** Keep a reference to the root cause. WicketTester will use it */ private final transient Throwable throwable; /** * Constructor. * * @param throwable * The exception to show * @param page * The page being rendered when the exception was thrown */ public ExceptionErrorPage(final Throwable throwable, final Page page) { this.throwable = throwable; // Add exception label add(new MultiLineLabel("exception", getErrorMessage(throwable))); add(new MultiLineLabel("stacktrace", getStackTrace(throwable))); // Get values String resource = ""; String markup = ""; MarkupStream markupStream = null; if (throwable instanceof MarkupException) { markupStream = ((MarkupException) throwable).getMarkupStream(); if (markupStream != null) { markup = markupStream.toHtmlDebugString(); resource = markupStream.getResource().toString(); } } // Create markup label final MultiLineLabel markupLabel = new MultiLineLabel("markup", markup); markupLabel.setEscapeModelStrings(false); // Add container with markup highlighted final WebMarkupContainer markupHighlight = new WebMarkupContainer("markupHighlight"); markupHighlight.add(markupLabel); markupHighlight.add(new Label("resource", resource)); add(markupHighlight); // Show container if markup stream is available markupHighlight.setVisible(markupStream != null); add(new Link<Void>("displayPageViewLink") { private static final long serialVersionUID = 1L; @Override public void onClick() { ExceptionErrorPage.this.replace(new PageView("componentTree", page)); setVisible(false); } }); add(new Label("componentTree", "")); } /** * Converts a Throwable to a string. * * @param throwable * The throwable * @return The string */ public String getErrorMessage(final Throwable throwable) { if (throwable != null) { StringBuilder sb = new StringBuilder(256); // first print the last cause List<Throwable> al = convertToList(throwable); int length = al.size() - 1; Throwable cause = al.get(length); sb.append("Last cause: ").append(cause.getMessage()).append('\n'); if (throwable instanceof WicketRuntimeException) { String msg = throwable.getMessage(); if ((msg != null) && (msg.equals(cause.getMessage()) == false)) { if (throwable instanceof MarkupException) { MarkupStream stream = ((MarkupException) throwable).getMarkupStream(); if (stream != null) { String text = "\n" + stream.toString(); if (msg.endsWith(text)) { msg = msg.substring(0, msg.length() - text.length()); } } } sb.append("WicketMessage: "); sb.append(msg); sb.append("\n\n"); } } return sb.toString(); } else { return "[Unknown]"; } } /** * Converts a Throwable to a string. * * @param throwable * The throwable * @return The string */ public String getStackTrace(final Throwable throwable) { if (throwable != null) { List<Throwable> al = convertToList(throwable); StringBuilder sb = new StringBuilder(256); // first print the last cause int length = al.size() - 1; Throwable cause = al.get(length); sb.append("Root cause:\n\n"); outputThrowable(cause, sb, false); if (length > 0) { sb.append("\n\nComplete stack:\n\n"); for (int i = 0; i < length; i++) { outputThrowable(al.get(i), sb, true); sb.append("\n"); } } return sb.toString(); } else { return "<Null Throwable>"; } } /** * @param throwable * @return xxx */ private List<Throwable> convertToList(final Throwable throwable) { List<Throwable> al = Generics.newArrayList(); Throwable cause = throwable; al.add(cause); while ((cause.getCause() != null) && (cause != cause.getCause())) { cause = cause.getCause(); al.add(cause); } return al; } /** * Outputs the throwable and its stacktrace to the stringbuffer. If stopAtWicketSerlvet is true * then the output will stop when the org.apache.wicket servlet is reached. sun.reflect. * packages are filtered out. * * @param cause * @param sb * @param stopAtWicketServlet */ private void outputThrowable(Throwable cause, StringBuilder sb, boolean stopAtWicketServlet) { sb.append(cause); sb.append("\n"); StackTraceElement[] trace = cause.getStackTrace(); for (int i = 0; i < trace.length; i++) { String traceString = trace[i].toString(); if (!(traceString.startsWith("sun.reflect.") && i > 1)) { sb.append(" at "); sb.append(traceString); sb.append("\n"); if (stopAtWicketServlet && (traceString.startsWith("org.apache.wicket.protocol.http.WicketServlet") || traceString.startsWith("org.apache.wicket.protocol.http.WicketFilter"))) { return; } } } } @Override protected void setHeaders(final WebResponse response) { response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR); } /** * Get access to the exception * * @return The exception */ public Throwable getThrowable() { return throwable; } }