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}