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