| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF 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.apache.commons.configuration2; |
| |
| import java.io.PrintStream; |
| import java.io.PrintWriter; |
| import java.io.StringWriter; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.Proxy; |
| import java.util.Iterator; |
| |
| import org.apache.commons.configuration2.event.ConfigurationErrorEvent; |
| import org.apache.commons.configuration2.event.Event; |
| import org.apache.commons.configuration2.event.EventListener; |
| import org.apache.commons.configuration2.event.EventSource; |
| import org.apache.commons.configuration2.event.EventType; |
| import org.apache.commons.configuration2.ex.ConfigurationRuntimeException; |
| import org.apache.commons.configuration2.sync.NoOpSynchronizer; |
| import org.apache.commons.configuration2.sync.Synchronizer; |
| import org.apache.commons.configuration2.tree.ExpressionEngine; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * Miscellaneous utility methods for configurations. |
| * |
| * @see ConfigurationConverter Utility methods to convert configurations. |
| * |
| * @author <a href="mailto:herve.quiroz@esil.univ-mrs.fr">Herve Quiroz</a> |
| * @author Emmanuel Bourg |
| * @version $Id$ |
| */ |
| public final class ConfigurationUtils |
| { |
| /** Constant for the name of the clone() method.*/ |
| private static final String METHOD_CLONE = "clone"; |
| |
| /** |
| * An array with interfaces to be implemented by a proxy for an immutable |
| * configuration. |
| */ |
| private static final Class<?>[] IMMUTABLE_CONFIG_IFCS = { |
| ImmutableConfiguration.class |
| }; |
| |
| /** |
| * An array with interfaces to be implemented by a proxy for an immutable |
| * hierarchical configuration. |
| */ |
| private static final Class<?>[] IMMUTABLE_HIERARCHICAL_CONFIG_IFCS = { |
| ImmutableHierarchicalConfiguration.class |
| }; |
| /** |
| * A dummy event source that is returned by {@code asEventSource()} if a |
| * mock object has to be returned. It provides empty dummy implementations |
| * for all interface methods. |
| */ |
| private static final EventSource DUMMY_EVENT_SOURCE = new EventSource() |
| { |
| |
| @Override |
| public <T extends Event> void addEventListener(EventType<T> eventType, |
| EventListener<? super T> listener) |
| { |
| } |
| |
| @Override |
| public <T extends Event> boolean removeEventListener( |
| EventType<T> eventType, EventListener<? super T> listener) |
| { |
| return false; |
| } |
| }; |
| |
| /** The logger.*/ |
| private static final Log LOG = LogFactory.getLog(ConfigurationUtils.class); |
| |
| /** |
| * Private constructor. Prevents instances from being created. |
| */ |
| private ConfigurationUtils() |
| { |
| // to prevent instantiation... |
| } |
| |
| /** |
| * Dump the configuration key/value mappings to some ouput stream. |
| * |
| * @param configuration the configuration |
| * @param out the output stream to dump the configuration to |
| */ |
| public static void dump(Configuration configuration, PrintStream out) |
| { |
| dump(configuration, new PrintWriter(out)); |
| } |
| |
| /** |
| * Dump the configuration key/value mappings to some writer. |
| * |
| * @param configuration the configuration |
| * @param out the writer to dump the configuration to |
| */ |
| public static void dump(Configuration configuration, PrintWriter out) |
| { |
| for (Iterator<String> keys = configuration.getKeys(); keys.hasNext();) |
| { |
| String key = keys.next(); |
| Object value = configuration.getProperty(key); |
| out.print(key); |
| out.print("="); |
| out.print(value); |
| |
| if (keys.hasNext()) |
| { |
| out.println(); |
| } |
| } |
| |
| out.flush(); |
| } |
| |
| /** |
| * Get a string representation of the key/value mappings of a |
| * configuration. |
| * |
| * @param configuration the configuration |
| * @return a string representation of the configuration |
| */ |
| public static String toString(Configuration configuration) |
| { |
| StringWriter writer = new StringWriter(); |
| dump(configuration, new PrintWriter(writer)); |
| return writer.toString(); |
| } |
| |
| /** |
| * <p>Copy all properties from the source configuration to the target |
| * configuration. Properties in the target configuration are replaced with |
| * the properties with the same key in the source configuration.</p> |
| * <p><em>Note:</em> This method is not able to handle some specifics of |
| * configurations derived from {@code AbstractConfiguration} (e.g. |
| * list delimiters). For a full support of all of these features the |
| * {@code copy()} method of {@code AbstractConfiguration} should |
| * be used. In a future release this method might become deprecated.</p> |
| * |
| * @param source the source configuration |
| * @param target the target configuration |
| * @since 1.1 |
| */ |
| public static void copy(Configuration source, Configuration target) |
| { |
| for (Iterator<String> keys = source.getKeys(); keys.hasNext();) |
| { |
| String key = keys.next(); |
| target.setProperty(key, source.getProperty(key)); |
| } |
| } |
| |
| /** |
| * <p>Append all properties from the source configuration to the target |
| * configuration. Properties in the source configuration are appended to |
| * the properties with the same key in the target configuration.</p> |
| * <p><em>Note:</em> This method is not able to handle some specifics of |
| * configurations derived from {@code AbstractConfiguration} (e.g. |
| * list delimiters). For a full support of all of these features the |
| * {@code copy()} method of {@code AbstractConfiguration} should |
| * be used. In a future release this method might become deprecated.</p> |
| * |
| * @param source the source configuration |
| * @param target the target configuration |
| * @since 1.1 |
| */ |
| public static void append(Configuration source, Configuration target) |
| { |
| for (Iterator<String> keys = source.getKeys(); keys.hasNext();) |
| { |
| String key = keys.next(); |
| target.addProperty(key, source.getProperty(key)); |
| } |
| } |
| |
| /** |
| * Converts the passed in configuration to a hierarchical one. If the |
| * configuration is already hierarchical, it is directly returned. Otherwise |
| * all properties are copied into a new hierarchical configuration. |
| * |
| * @param conf the configuration to convert |
| * @return the new hierarchical configuration (the result is <b>null</b> if |
| * and only if the passed in configuration is <b>null</b>) |
| * @since 1.3 |
| */ |
| public static HierarchicalConfiguration<?> convertToHierarchical( |
| Configuration conf) |
| { |
| return convertToHierarchical(conf, null); |
| } |
| |
| /** |
| * Converts the passed in {@code Configuration} object to a |
| * hierarchical one using the specified {@code ExpressionEngine}. This |
| * conversion works by adding the keys found in the configuration to a newly |
| * created hierarchical configuration. When adding new keys to a |
| * hierarchical configuration the keys are interpreted by its |
| * {@code ExpressionEngine}. If they contain special characters (e.g. |
| * brackets) that are treated in a special way by the default expression |
| * engine, it may be necessary using a specific engine that can deal with |
| * such characters. Otherwise <b>null</b> can be passed in for the |
| * {@code ExpressionEngine}; then the default expression engine is |
| * used. If the passed in configuration is already hierarchical, it is |
| * directly returned. (However, the {@code ExpressionEngine} is set if |
| * it is not <b>null</b>.) Otherwise all properties are copied into a new |
| * hierarchical configuration. |
| * |
| * @param conf the configuration to convert |
| * @param engine the {@code ExpressionEngine} for the hierarchical |
| * configuration or <b>null</b> for the default |
| * @return the new hierarchical configuration (the result is <b>null</b> if |
| * and only if the passed in configuration is <b>null</b>) |
| * @since 1.6 |
| */ |
| public static HierarchicalConfiguration<?> convertToHierarchical( |
| Configuration conf, ExpressionEngine engine) |
| { |
| if (conf == null) |
| { |
| return null; |
| } |
| |
| if (conf instanceof HierarchicalConfiguration) |
| { |
| HierarchicalConfiguration<?> hc = (HierarchicalConfiguration<?>) conf; |
| if (engine != null) |
| { |
| hc.setExpressionEngine(engine); |
| } |
| |
| return hc; |
| } |
| else |
| { |
| BaseHierarchicalConfiguration hc = new BaseHierarchicalConfiguration(); |
| if (engine != null) |
| { |
| hc.setExpressionEngine(engine); |
| } |
| |
| // Per default, a DisabledListDelimiterHandler is set. |
| // So list delimiters in property values are not an issue. |
| hc.append(conf); |
| return hc; |
| } |
| } |
| |
| /** |
| * Clones the given configuration object if this is possible. If the passed |
| * in configuration object implements the {@code Cloneable} |
| * interface, its {@code clone()} method will be invoked. Otherwise |
| * an exception will be thrown. |
| * |
| * @param config the configuration object to be cloned (can be <b>null</b>) |
| * @return the cloned configuration (<b>null</b> if the argument was |
| * <b>null</b>, too) |
| * @throws ConfigurationRuntimeException if cloning is not supported for |
| * this object |
| * @since 1.3 |
| */ |
| public static Configuration cloneConfiguration(Configuration config) |
| throws ConfigurationRuntimeException |
| { |
| if (config == null) |
| { |
| return null; |
| } |
| else |
| { |
| try |
| { |
| return (Configuration) clone(config); |
| } |
| catch (CloneNotSupportedException cnex) |
| { |
| throw new ConfigurationRuntimeException(cnex); |
| } |
| } |
| } |
| |
| /** |
| * Returns a clone of the passed in object if cloning is supported or the |
| * object itself if not. This method checks whether the passed in object |
| * implements the {@code Cloneable} interface. If this is the case, the |
| * {@code clone()} method is invoked. Otherwise, the object is directly |
| * returned. Errors that might occur during reflection calls are caught and |
| * also cause this method to return the original object. |
| * |
| * @param obj the object to be cloned |
| * @return the result of the cloning attempt |
| * @since 2.0 |
| */ |
| public static Object cloneIfPossible(Object obj) |
| { |
| try |
| { |
| return clone(obj); |
| } |
| catch (Exception ex) |
| { |
| return obj; |
| } |
| } |
| |
| /** |
| * An internally used helper method for cloning objects. This implementation |
| * is not very sophisticated nor efficient. Maybe it can be replaced by an |
| * implementation from Commons Lang later. The method checks whether the |
| * passed in object implements the {@code Cloneable} interface. If |
| * this is the case, the {@code clone()} method is invoked by |
| * reflection. Errors that occur during the cloning process are re-thrown as |
| * runtime exceptions. |
| * |
| * @param obj the object to be cloned |
| * @return the cloned object |
| * @throws CloneNotSupportedException if the object cannot be cloned |
| */ |
| static Object clone(Object obj) throws CloneNotSupportedException |
| { |
| if (obj instanceof Cloneable) |
| { |
| try |
| { |
| Method m = obj.getClass().getMethod(METHOD_CLONE); |
| return m.invoke(obj); |
| } |
| catch (NoSuchMethodException nmex) |
| { |
| throw new CloneNotSupportedException( |
| "No clone() method found for class" |
| + obj.getClass().getName()); |
| } |
| catch (IllegalAccessException iaex) |
| { |
| throw new ConfigurationRuntimeException(iaex); |
| } |
| catch (InvocationTargetException itex) |
| { |
| throw new ConfigurationRuntimeException(itex); |
| } |
| } |
| else |
| { |
| throw new CloneNotSupportedException(obj.getClass().getName() |
| + " does not implement Cloneable"); |
| } |
| } |
| |
| /** |
| * Creates a clone of the specified {@code Synchronizer}. This method can be |
| * called by {@code clone()} implementations in configuration classes that |
| * also need to copy the {@code Synchronizer} object. This method can handle |
| * some well-known {@code Synchronizer} implementations directly. For other |
| * classes, it uses the following algorithm: |
| * <ul> |
| * <li>If the class of the {@code Synchronizer} has a standard constructor, |
| * a new instance is created using reflection.</li> |
| * <li>If this is not possible, it is tried whether the object can be |
| * cloned.</li> |
| * </ul> |
| * If all attempts fail, a {@code ConfigurationRuntimeException} is thrown. |
| * |
| * @param sync the {@code Synchronizer} object to be cloned |
| * @return the clone of this {@code Synchronizer} |
| * @throws ConfigurationRuntimeException if no clone can be created |
| * @throws IllegalArgumentException if <b>null</b> is passed in |
| */ |
| public static Synchronizer cloneSynchronizer(Synchronizer sync) |
| { |
| if (sync == null) |
| { |
| throw new IllegalArgumentException("Synchronizer must not be null!"); |
| } |
| if (NoOpSynchronizer.INSTANCE == sync) |
| { |
| return sync; |
| } |
| |
| try |
| { |
| return sync.getClass().newInstance(); |
| } |
| catch (Exception ex) |
| { |
| LOG.info("Cannot create new instance of " + sync.getClass()); |
| } |
| |
| try |
| { |
| return (Synchronizer) clone(sync); |
| } |
| catch (CloneNotSupportedException cnex) |
| { |
| throw new ConfigurationRuntimeException( |
| "Cannot clone Synchronizer " + sync); |
| } |
| } |
| |
| /** |
| * Enables runtime exceptions for the specified configuration object. This |
| * method can be used for configuration implementations that may face errors |
| * on normal property access, e.g. {@code DatabaseConfiguration} or |
| * {@code JNDIConfiguration}. Per default such errors are simply |
| * logged and then ignored. This implementation will register a special |
| * {@link EventListener} that throws a runtime |
| * exception (namely a {@code ConfigurationRuntimeException}) on |
| * each received error event. |
| * |
| * @param src the configuration, for which runtime exceptions are to be |
| * enabled; this configuration must implement {@link EventSource} |
| */ |
| public static void enableRuntimeExceptions(Configuration src) |
| { |
| if (!(src instanceof EventSource)) |
| { |
| throw new IllegalArgumentException( |
| "Configuration must implement EventSource!"); |
| } |
| ((EventSource) src).addEventListener(ConfigurationErrorEvent.ANY, |
| new EventListener<ConfigurationErrorEvent>() |
| { |
| @Override |
| public void onEvent(ConfigurationErrorEvent event) |
| { |
| // Throw a runtime exception |
| throw new ConfigurationRuntimeException(event |
| .getCause()); |
| } |
| }); |
| } |
| |
| /** |
| * Loads the class with the given name. This method is used whenever a class |
| * has to be loaded dynamically. It first tries the current thread's context |
| * class loader. If this fails, the class loader of this class is tried. |
| * |
| * @param clsName the name of the class to be loaded |
| * @return the loaded class |
| * @throws ClassNotFoundException if the class cannot be resolved |
| * @since 2.0 |
| */ |
| public static Class<?> loadClass(String clsName) |
| throws ClassNotFoundException |
| { |
| if (LOG.isDebugEnabled()) |
| { |
| LOG.debug("Loading class " + clsName); |
| } |
| |
| ClassLoader cl = Thread.currentThread().getContextClassLoader(); |
| try |
| { |
| if (cl != null) |
| { |
| return cl.loadClass(clsName); |
| } |
| } |
| catch (ClassNotFoundException cnfex) |
| { |
| LOG.info("Could not load class " + clsName |
| + " using CCL. Falling back to default CL.", cnfex); |
| } |
| |
| return ConfigurationUtils.class.getClassLoader().loadClass(clsName); |
| } |
| |
| /** |
| * Loads the class with the specified name re-throwing |
| * {@code ClassNotFoundException} exceptions as runtime exceptions. This |
| * method works like {@link #loadClass(String)}. However, checked exceptions |
| * are caught and re-thrown as {@code ConfigurationRuntimeException}. |
| * |
| * @param clsName the name of the class to be loaded |
| * @return the loaded class |
| * @throws ConfigurationRuntimeException if the class cannot be resolved |
| * @since 2.0 |
| */ |
| public static Class<?> loadClassNoEx(String clsName) |
| { |
| try |
| { |
| return loadClass(clsName); |
| } |
| catch (ClassNotFoundException cnfex) |
| { |
| throw new ConfigurationRuntimeException("Cannot load class " |
| + clsName, cnfex); |
| } |
| } |
| |
| /** |
| * Creates an {@code ImmutableConfiguration} from the given |
| * {@code Configuration} object. This method creates a proxy object wrapping |
| * the original configuration and making it available under the |
| * {@code ImmutableConfiguration} interface. Through this interface the |
| * configuration cannot be manipulated. It is also not possible to cast the |
| * returned object back to a {@code Configuration} instance to circumvent |
| * this protection. |
| * |
| * @param c the {@code Configuration} to be wrapped (must not be |
| * <b>null</b>) |
| * @return an {@code ImmutableConfiguration} view on the specified |
| * {@code Configuration} object |
| * @throws NullPointerException if the passed in {@code Configuration} is |
| * <b>null</b> |
| * @since 2.0 |
| */ |
| public static ImmutableConfiguration unmodifiableConfiguration( |
| Configuration c) |
| { |
| return createUnmodifiableConfiguration(IMMUTABLE_CONFIG_IFCS, c); |
| } |
| |
| /** |
| * Creates an {@code ImmutableHierarchicalConfiguration} from the given |
| * {@code HierarchicalConfiguration} object. This method works exactly like |
| * the method with the same name, but it operates on hierarchical |
| * configurations. |
| * |
| * @param c the {@code HierarchicalConfiguration} to be wrapped (must not be |
| * <b>null</b>) |
| * @return an {@code ImmutableHierarchicalConfiguration} view on the |
| * specified {@code HierarchicalConfiguration} object |
| * @throws NullPointerException if the passed in |
| * {@code HierarchicalConfiguration} is <b>null</b> |
| * @since 2.0 |
| */ |
| public static ImmutableHierarchicalConfiguration unmodifiableConfiguration( |
| HierarchicalConfiguration<?> c) |
| { |
| return (ImmutableHierarchicalConfiguration) createUnmodifiableConfiguration( |
| IMMUTABLE_HIERARCHICAL_CONFIG_IFCS, c); |
| } |
| |
| /** |
| * Helper method for creating a proxy for an unmodifiable configuration. The |
| * interfaces the proxy should implement are passed as argument. |
| * |
| * @param ifcs an array with the interface classes the proxy must implement |
| * @param c the configuration object to be wrapped |
| * @return a proxy object for an immutable configuration |
| * @throws NullPointerException if the configuration is <b>null</b> |
| */ |
| private static ImmutableConfiguration createUnmodifiableConfiguration( |
| Class<?>[] ifcs, Configuration c) |
| { |
| return (ImmutableConfiguration) Proxy.newProxyInstance( |
| ConfigurationUtils.class.getClassLoader(), ifcs, |
| new ImmutableConfigurationInvocationHandler(c)); |
| } |
| |
| /** |
| * Casts the specified object to an {@code EventSource} if possible. The |
| * boolean argument determines the method's behavior if the object does not |
| * implement the {@code EventSource} event: if set to <b>false</b>, a |
| * {@code ConfigurationRuntimeException} is thrown; if set to <b>true</b>, a |
| * dummy {@code EventSource} is returned; on this object all methods can be |
| * called, but they do not have any effect. |
| * |
| * @param obj the object to be cast as {@code EventSource} |
| * @param mockIfUnsupported a flag whether a mock object should be returned |
| * if necessary |
| * @return an {@code EventSource} |
| * @throws ConfigurationRuntimeException if the object cannot be cast to |
| * {@code EventSource} and the mock flag is <b>false</b> |
| * @since 2.0 |
| */ |
| public static EventSource asEventSource(Object obj, |
| boolean mockIfUnsupported) |
| { |
| if (obj instanceof EventSource) |
| { |
| return (EventSource) obj; |
| } |
| |
| if (!mockIfUnsupported) |
| { |
| throw new ConfigurationRuntimeException( |
| "Cannot cast to EventSource: " + obj); |
| } |
| return DUMMY_EVENT_SOURCE; |
| } |
| } |