Java tutorial
// Licensed to the Software Freedom Conservancy (SFC) under one // or more contributor license agreements. See the NOTICE file // distributed with this work for additional information // regarding copyright ownership. The SFC 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.openqa.selenium.remote; import static org.openqa.selenium.remote.ErrorCodes.SUCCESS; import com.google.common.base.Function; import com.google.common.base.Optional; import com.google.common.base.Predicates; import com.google.common.base.Throwables; import com.google.common.collect.Iterables; import com.google.common.primitives.Ints; import org.openqa.selenium.UnhandledAlertException; import org.openqa.selenium.WebDriverException; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.math.BigDecimal; import java.math.RoundingMode; import java.util.List; import java.util.Map; /** * Maps exceptions to status codes for sending over the wire. * * @author jmleyba@gmail.com (Jason Leyba) */ public class ErrorHandler { private static final String MESSAGE = "message"; private static final String SCREEN_SHOT = "screen"; private static final String CLASS = "class"; private static final String STACK_TRACE = "stackTrace"; private static final String LINE_NUMBER = "lineNumber"; private static final String METHOD_NAME = "methodName"; private static final String CLASS_NAME = "className"; private static final String FILE_NAME = "fileName"; private static final String UNKNOWN_CLASS = "<anonymous class>"; private static final String UNKNOWN_METHOD = "<anonymous method>"; private static final String UNKNOWN_FILE = null; private ErrorCodes errorCodes; private boolean includeServerErrors; public ErrorHandler() { this(true); } /** * @param includeServerErrors Whether to include server-side details in thrown exceptions if the * information is available. */ public ErrorHandler(boolean includeServerErrors) { this.includeServerErrors = includeServerErrors; this.errorCodes = new ErrorCodes(); } /** * @param includeServerErrors Whether to include server-side details in thrown exceptions if the * information is available. * @param codes The ErrorCodes object to use for linking error codes to exceptions. */ public ErrorHandler(ErrorCodes codes, boolean includeServerErrors) { this.includeServerErrors = includeServerErrors; this.errorCodes = codes; } public boolean isIncludeServerErrors() { return includeServerErrors; } public void setIncludeServerErrors(boolean includeServerErrors) { this.includeServerErrors = includeServerErrors; } @SuppressWarnings("unchecked") public Response throwIfResponseFailed(Response response, long duration) throws RuntimeException { if (response.getStatus() == null || response.getStatus() == SUCCESS) { return response; } if (response.getValue() instanceof Throwable) { throw Throwables.propagate((Throwable) response.getValue()); } Class<? extends WebDriverException> outerErrorType = errorCodes.getExceptionType(response.getStatus()); Object value = response.getValue(); String message = null; Throwable cause = null; if (value instanceof Map) { Map<String, Object> rawErrorData = (Map<String, Object>) value; try { message = (String) rawErrorData.get(MESSAGE); } catch (ClassCastException e) { // Ok, try to recover gracefully. message = String.valueOf(e); } Throwable serverError = rebuildServerError(rawErrorData, response.getStatus()); // If serverError is null, then the server did not provide a className (only expected if // the server is a Java process) or a stack trace. The lack of a className is OK, but // not having a stacktrace really hurts our ability to debug problems. if (serverError == null) { if (includeServerErrors) { // TODO: this should probably link to a wiki article with more info. message += " (WARNING: The server did not provide any stacktrace information)"; } } else if (!includeServerErrors) { // TODO: wiki article with more info. message += " (WARNING: The client has suppressed server-side stacktraces)"; } else { cause = serverError; } if (rawErrorData.get(SCREEN_SHOT) != null) { cause = new ScreenshotException(String.valueOf(rawErrorData.get(SCREEN_SHOT)), cause); } } else if (value != null) { message = String.valueOf(value); } String duration1 = duration(duration); if (message != null && !message.contains(duration1)) { message = message + duration1; } WebDriverException toThrow = null; if (outerErrorType.equals(UnhandledAlertException.class) && value instanceof Map) { toThrow = createUnhandledAlertException(value); } if (toThrow == null) { toThrow = createThrowable(outerErrorType, new Class<?>[] { String.class, Throwable.class }, new Object[] { message, cause }); } if (toThrow == null) { toThrow = createThrowable(outerErrorType, new Class<?>[] { String.class }, new Object[] { message }); } if (toThrow == null) { toThrow = new WebDriverException(message, cause); } throw toThrow; } @SuppressWarnings("unchecked") private UnhandledAlertException createUnhandledAlertException(Object value) { Map<String, Object> rawErrorData = (Map<String, Object>) value; if (rawErrorData.containsKey("alert") || rawErrorData.containsKey("alertText")) { Object alertText = rawErrorData.get("alertText"); if (alertText == null) { Map<String, Object> alert = (Map<String, Object>) rawErrorData.get("alert"); if (alert != null) { alertText = alert.get("text"); } } return createThrowable(UnhandledAlertException.class, new Class<?>[] { String.class, String.class }, new Object[] { rawErrorData.get("message"), alertText }); } return null; } private String duration(long duration) { String prefix = "\nCommand duration or timeout: "; if (duration < 1000) { return prefix + duration + " milliseconds"; } return prefix + (new BigDecimal(duration).divide(new BigDecimal(1000)).setScale(2, RoundingMode.HALF_UP)) + " seconds"; } private <T extends Throwable> T createThrowable(Class<T> clazz, Class<?>[] parameterTypes, Object[] parameters) { try { Constructor<T> constructor = clazz.getConstructor(parameterTypes); return constructor.newInstance(parameters); } catch (NoSuchMethodException e) { // Do nothing - fall through. } catch (InvocationTargetException e) { // Do nothing - fall through. } catch (InstantiationException e) { // Do nothing - fall through. } catch (IllegalAccessException e) { // Do nothing - fall through. } catch (OutOfMemoryError error) { // It can happen... } return null; } private Throwable rebuildServerError(Map<String, Object> rawErrorData, int responseStatus) { if (!rawErrorData.containsKey(CLASS) && !rawErrorData.containsKey(STACK_TRACE)) { // Not enough information for us to try to rebuild an error. return null; } Throwable toReturn = null; String message = (String) rawErrorData.get(MESSAGE); Class<?> clazz = null; // First: allow Remote Driver to specify the Selenium Server internal exception if (rawErrorData.containsKey(CLASS)) { String className = (String) rawErrorData.get(CLASS); try { clazz = Class.forName(className); } catch (ClassNotFoundException ignored) { // Ok, fall-through } } // If the above fails, map Response Status to Exception class if (null == clazz) { clazz = errorCodes.getExceptionType(responseStatus); } if (clazz.equals(UnhandledAlertException.class)) { toReturn = createUnhandledAlertException(rawErrorData); } else if (Throwable.class.isAssignableFrom(clazz)) { @SuppressWarnings({ "unchecked" }) Class<? extends Throwable> throwableType = (Class<? extends Throwable>) clazz; toReturn = createThrowable(throwableType, new Class<?>[] { String.class }, new Object[] { message }); } if (toReturn == null) { toReturn = new UnknownServerException(message); } // Note: if we have a class name above, we should always have a stack trace. // The inverse is not always true. StackTraceElement[] stackTrace = new StackTraceElement[0]; if (rawErrorData.containsKey(STACK_TRACE)) { @SuppressWarnings({ "unchecked" }) List<Map<String, Object>> stackTraceInfo = (List<Map<String, Object>>) rawErrorData.get(STACK_TRACE); Iterable<StackTraceElement> stackFrames = Iterables.transform(stackTraceInfo, new FrameInfoToStackFrame()); stackFrames = Iterables.filter(stackFrames, Predicates.notNull()); stackTrace = Iterables.toArray(stackFrames, StackTraceElement.class); } toReturn.setStackTrace(stackTrace); return toReturn; } /** * Exception used as a place holder if the server returns an error without a stack trace. */ public static class UnknownServerException extends WebDriverException { private UnknownServerException(String s) { super(s); } } /** * Function that can rebuild a {@link StackTraceElement} from the frame info included with a * WebDriver JSON response. */ private static class FrameInfoToStackFrame implements Function<Map<String, Object>, StackTraceElement> { public StackTraceElement apply(Map<String, Object> frameInfo) { if (frameInfo == null) { return null; } Optional<Number> maybeLineNumberInteger = Optional.absent(); final Object lineNumberObject = frameInfo.get(LINE_NUMBER); if (lineNumberObject instanceof Number) { maybeLineNumberInteger = Optional.of((Number) lineNumberObject); } else if (lineNumberObject != null) { // might be a Number as a String maybeLineNumberInteger = Optional.fromNullable((Number) Ints.tryParse(lineNumberObject.toString())); } // default -1 for unknown, see StackTraceElement constructor javadoc final int lineNumber = maybeLineNumberInteger.or(-1).intValue(); // Gracefully handle remote servers that don't (or can't) send back // complete stack trace info. At least some of this information should // be included... String className = frameInfo.containsKey(CLASS_NAME) ? toStringOrNull(frameInfo.get(CLASS_NAME)) : UNKNOWN_CLASS; String methodName = frameInfo.containsKey(METHOD_NAME) ? toStringOrNull(frameInfo.get(METHOD_NAME)) : UNKNOWN_METHOD; String fileName = frameInfo.containsKey(FILE_NAME) ? toStringOrNull(frameInfo.get(FILE_NAME)) : UNKNOWN_FILE; return new StackTraceElement(className, methodName, fileName, lineNumber); } private static String toStringOrNull(Object o) { return o == null ? null : o.toString(); } } }