001// Licensed under the Apache License, Version 2.0 (the "License");
002// you may not use this file except in compliance with the License.
003// You may obtain a copy of the License at
004//
005// http://www.apache.org/licenses/LICENSE-2.0
006//
007// Unless required by applicable law or agreed to in writing, software
008// distributed under the License is distributed on an "AS IS" BASIS,
009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
010// See the License for the specific language governing permissions and
011// limitations under the License.
012
013package org.apache.tapestry5.internal.services;
014
015import org.apache.tapestry5.ContextAwareException;
016import org.apache.tapestry5.ExceptionHandlerAssistant;
017import org.apache.tapestry5.SymbolConstants;
018import org.apache.tapestry5.beanmodel.services.*;
019import org.apache.tapestry5.commons.internal.util.TapestryException;
020import org.apache.tapestry5.commons.util.ExceptionUtils;
021import org.apache.tapestry5.http.Link;
022import org.apache.tapestry5.http.services.Request;
023import org.apache.tapestry5.http.services.Response;
024import org.apache.tapestry5.internal.InternalConstants;
025import org.apache.tapestry5.internal.structure.Page;
026import org.apache.tapestry5.ioc.ServiceResources;
027import org.apache.tapestry5.ioc.annotations.Symbol;
028import org.apache.tapestry5.ioc.internal.OperationException;
029import org.apache.tapestry5.json.JSONObject;
030import org.apache.tapestry5.runtime.ComponentEventException;
031import org.apache.tapestry5.services.ComponentClassResolver;
032import org.apache.tapestry5.services.ExceptionReporter;
033import org.apache.tapestry5.services.RequestExceptionHandler;
034import org.slf4j.Logger;
035
036import javax.servlet.http.HttpServletResponse;
037import java.io.IOException;
038import java.io.OutputStream;
039import java.net.URLEncoder;
040import java.util.Arrays;
041import java.util.HashMap;
042import java.util.List;
043import java.util.Map;
044import java.util.Map.Entry;
045
046/**
047 * Default implementation of {@link RequestExceptionHandler} that displays the standard ExceptionReport page. Similarly to the
048 * servlet spec's standard error handling, the default exception handler allows configuring handlers for specific types of
049 * exceptions. The error-page/exception-type configuration in web.xml does not work in Tapestry application as errors are
050 * wrapped in Tapestry's exception types (see {@link OperationException} and {@link ComponentEventException} ).
051 *
052 * Configurations are flexible. You can either contribute a {@link ExceptionHandlerAssistant} to use arbitrary complex logic
053 * for error handling or a page class to render for the specific exception. Additionally, exceptions can carry context for the
054 * error page. Exception context is formed either from the name of Exception (e.g. SmtpNotRespondingException {@code ->} ServiceFailure mapping
055 * would render a page with URL /servicefailure/smtpnotresponding) or they can implement {@link ContextAwareException} interface.
056 *
057 * If no configured exception type is found, the default exception page {@link SymbolConstants#EXCEPTION_REPORT_PAGE} is rendered.
058 * This fallback exception page must implement the {@link org.apache.tapestry5.services.ExceptionReporter} interface.
059 */
060public class DefaultRequestExceptionHandler implements RequestExceptionHandler
061{
062    private final RequestPageCache pageCache;
063
064    private final PageResponseRenderer renderer;
065
066    private final Logger logger;
067
068    private final String pageName;
069
070    private final Request request;
071
072    private final Response response;
073
074    private final ComponentClassResolver componentClassResolver;
075
076    private final LinkSource linkSource;
077
078    private final ExceptionReporter exceptionReporter;
079
080    // should be Class<? extends Throwable>, Object but it's not allowed to configure subtypes
081    private final Map<Class, Object> configuration;
082
083    /**
084     * @param configuration
085     *         A map of Exception class and handler values. A handler is either a page class or an ExceptionHandlerAssistant. ExceptionHandlerAssistant can be a class
086     */
087    @SuppressWarnings("rawtypes")
088    public DefaultRequestExceptionHandler(RequestPageCache pageCache,
089                                          PageResponseRenderer renderer,
090                                          Logger logger,
091                                          @Symbol(SymbolConstants.EXCEPTION_REPORT_PAGE)
092                                          String pageName,
093                                          Request request,
094                                          Response response,
095                                          ComponentClassResolver componentClassResolver,
096                                          LinkSource linkSource,
097                                          ServiceResources serviceResources,
098                                          ExceptionReporter exceptionReporter,
099                                          Map<Class, Object> configuration)
100    {
101        this.pageCache = pageCache;
102        this.renderer = renderer;
103        this.logger = logger;
104        this.pageName = pageName;
105        this.request = request;
106        this.response = response;
107        this.componentClassResolver = componentClassResolver;
108        this.linkSource = linkSource;
109        this.exceptionReporter = exceptionReporter;
110
111        Map<Class<ExceptionHandlerAssistant>, ExceptionHandlerAssistant> handlerAssistants = new HashMap<Class<ExceptionHandlerAssistant>, ExceptionHandlerAssistant>();
112
113        for (Entry<Class, Object> entry : configuration.entrySet())
114        {
115            if (!Throwable.class.isAssignableFrom(entry.getKey()))
116                throw new IllegalArgumentException(Throwable.class.getName() + " is the only allowable key type but " + entry.getKey().getName()
117                        + " was contributed");
118
119            if (entry.getValue() instanceof Class && ExceptionHandlerAssistant.class.isAssignableFrom((Class) entry.getValue()))
120            {
121                @SuppressWarnings("unchecked")
122                Class<ExceptionHandlerAssistant> handlerType = (Class<ExceptionHandlerAssistant>) entry.getValue();
123                ExceptionHandlerAssistant assistant = handlerAssistants.get(handlerType);
124                if (assistant == null)
125                {
126                    assistant = (ExceptionHandlerAssistant) serviceResources.autobuild(handlerType);
127                    handlerAssistants.put(handlerType, assistant);
128                }
129                entry.setValue(assistant);
130            }
131        }
132        this.configuration = configuration;
133    }
134
135    /**
136     * Handles the exception thrown at some point the request was being processed
137     *
138     * First checks if there was a specific exception handler/page configured for this exception type, it's super class or super-super class.
139     * Renders the default exception page if none was configured.
140     *
141     * @param exception
142     *         The exception that was thrown
143     */
144    @SuppressWarnings({"rawtypes", "unchecked"})
145    public void handleRequestException(Throwable exception) throws IOException
146    {
147        // skip handling of known exceptions if there are none configured
148        if (configuration.isEmpty())
149        {
150            renderException(exception);
151            return;
152        }
153
154        Throwable cause = exception;
155
156        // Depending on where the error was thrown, there could be several levels of wrappers..
157        // For exceptions in component operations, it's OperationException -> ComponentEventException -> <Target>Exception
158
159        // Throw away the wrapped exceptions first
160        while (cause instanceof TapestryException)
161        {
162            if (cause.getCause() == null) break;
163            cause = cause.getCause();
164        }
165
166        Class<?> causeClass = cause.getClass();
167        if (!configuration.containsKey(causeClass))
168        {
169            // try at most two level of superclasses before delegating back to the default exception handler
170            causeClass = causeClass.getSuperclass();
171            if (causeClass == null || !configuration.containsKey(causeClass))
172            {
173                causeClass = causeClass.getSuperclass();
174                if (causeClass == null || !configuration.containsKey(causeClass))
175                {
176                    renderException(exception);
177                    return;
178                }
179            }
180        }
181
182        Object[] exceptionContext = formExceptionContext(cause);
183        Object value = configuration.get(causeClass);
184        Object page = null;
185        ExceptionHandlerAssistant assistant = null;
186        if (value instanceof ExceptionHandlerAssistant)
187        {
188            assistant = (ExceptionHandlerAssistant) value;
189            // in case the assistant changes the context
190            List context = Arrays.asList(exceptionContext);
191            page = assistant.handleRequestException(exception, context);
192            exceptionContext = context.toArray();
193        } else if (!(value instanceof Class))
194        {
195            renderException(exception);
196            return;
197        } else page = value;
198
199        if (page == null) return;
200
201        try
202        {
203            if (page instanceof Class)
204                page = componentClassResolver.resolvePageClassNameToPageName(((Class) page).getName());
205
206            Link link = page instanceof Link
207                    ? (Link) page
208                    : linkSource.createPageRenderLink(page.toString(), false, exceptionContext);
209
210            if (request.isXHR())
211            {
212                OutputStream os = response.getOutputStream("application/json;charset=UTF-8");
213
214                JSONObject reply = new JSONObject();
215                reply.in(InternalConstants.PARTIAL_KEY).put("redirectURL", link.toRedirectURI());
216
217                os.write(reply.toCompactString().getBytes("UTF-8"));
218
219                os.close();
220
221                return;
222            }
223
224            // Normal behavior is just a redirect.
225
226            response.sendRedirect(link);
227        }
228        // The above could throw an exception if we are already on a render request, but it's
229        // user's responsibility not to abuse the mechanism
230        catch (Exception e)
231        {
232            logger.warn("A new exception was thrown while trying to handle an instance of {}.",
233                    exception.getClass().getName(), e);
234            // Nothing to do but delegate
235            renderException(exception);
236        }
237    }
238
239    private void renderException(Throwable exception) throws IOException
240    {
241        logger.error("Processing of request failed with uncaught exception: {}", exception, exception);
242
243        // In the case where one of the contributed rules, above, changes the behavior, then we don't report the
244        // exception. This is just for exceptions that are going to be rendered, real failures.
245        exceptionReporter.reportException(exception);
246
247        // TAP5-233: Make sure the client knows that an error occurred.
248
249        response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
250
251        String rawMessage = ExceptionUtils.toMessage(exception);
252
253        // Encode it compatibly with the JavaScript escape() function.
254
255        String encoded = URLEncoder.encode(rawMessage, "UTF-8").replace("+", "%20");
256
257        response.setHeader("X-Tapestry-ErrorMessage", encoded);
258
259        Page page = pageCache.get(pageName);
260
261        org.apache.tapestry5.services.ExceptionReporter rootComponent = (org.apache.tapestry5.services.ExceptionReporter) page.getRootComponent();
262
263        // Let the page set up for the new exception.
264
265        rootComponent.reportException(exception);
266
267        renderer.renderPageResponse(page);
268    }
269
270    /**
271     * Form exception context either from the name of the exception, or the context the exception contains if it's of type
272     * {@link ContextAwareException}
273     *
274     * @param exception
275     *         The exception that the context is formed for
276     * @return Returns an array of objects to be used as the exception context
277     */
278    @SuppressWarnings({"unchecked", "rawtypes"})
279    protected Object[] formExceptionContext(Throwable exception)
280    {
281        if (exception instanceof ContextAwareException) return ((ContextAwareException) exception).getContext();
282
283        Class exceptionClass = exception.getClass();
284        // pick the first class in the hierarchy that's not anonymous, probably no reason check for array types
285        while ("".equals(exceptionClass.getSimpleName()))
286            exceptionClass = exceptionClass.getSuperclass();
287
288        // check if exception type is plain runtimeException - yes, we really want the test to be this way
289        if (exceptionClass.isAssignableFrom(RuntimeException.class))
290            return exception.getMessage() == null ? new Object[0] : new Object[]{exception.getMessage().toLowerCase()};
291
292        // otherwise, form the context from the exception type name
293        String exceptionType = exceptionClass.getSimpleName();
294        if (exceptionType.endsWith("Exception")) exceptionType = exceptionType.substring(0, exceptionType.length() - 9);
295        return new Object[]{exceptionType.toLowerCase()};
296    }
297
298}