    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}