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Posted to commits@commons.apache.org by oh...@apache.org on 2013/11/26 21:34:07 UTC
svn commit: r1545824 - in /commons/proper/configuration/trunk/src:
main/java/org/apache/commons/configuration/builder/DefaultParametersManager.java
test/java/org/apache/commons/configuration/builder/TestDefaultParametersManager.java
Author: oheger
Date: Tue Nov 26 20:34:06 2013
New Revision: 1545824
URL: http://svn.apache.org/r1545824
Log:
Extracted functionality related to default values to a separate class.
The new class DefaultParametersManager is now responsible for managing and
applying DefaultParametersHandler objects.
Added:
commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/builder/DefaultParametersManager.java
commons/proper/configuration/trunk/src/test/java/org/apache/commons/configuration/builder/TestDefaultParametersManager.java
Added: commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/builder/DefaultParametersManager.java
URL: http://svn.apache.org/viewvc/commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/builder/DefaultParametersManager.java?rev=1545824&view=auto
==============================================================================
--- commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/builder/DefaultParametersManager.java (added)
+++ commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/builder/DefaultParametersManager.java Tue Nov 26 20:34:06 2013
@@ -0,0 +1,275 @@
+/*
+ * 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.configuration.builder;
+
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import org.apache.commons.configuration.builder.fluent.FileBasedBuilderParameters;
+import org.apache.commons.configuration.builder.fluent.PropertiesBuilderParameters;
+import org.apache.commons.configuration.builder.fluent.XMLBuilderParameters;
+
+/**
+ * <p>
+ * A class for managing a set of {@link DefaultParametersHandler} objects.
+ * </p>
+ * <p>
+ * This class provides functionality for registering and removing
+ * {@code DefaultParametersHandler} objects for arbitrary parameters classes.
+ * The handlers registered at an instance can then be applied on a passed in
+ * parameters object, so that it gets initialized with the provided default
+ * values.
+ * </p>
+ * <p>
+ * Usage of this class is as follows: First the {@code DefaultParametersHandler}
+ * objects to be supported must be registered using one of the
+ * {@code registerDefaultHandler()} methods. After that arbitrary parameters
+ * objects can be passed to the {@code initializeParameters()} method. This
+ * causes all {@code DefaultParametersHandler} objects supporting this
+ * parameters class to be invoked on this object.
+ * </p>
+ * <p>
+ * Implementation note: This class is thread-safe.
+ * </p>
+ *
+ * @version $Id: $
+ * @since 2.0
+ */
+public class DefaultParametersManager
+{
+ /** A collection with the registered default handlers. */
+ private final Collection<DefaultHandlerData> defaultHandlers;
+
+ /**
+ * Creates a new instance of {@code DefaultParametersManager}.
+ */
+ public DefaultParametersManager()
+ {
+ defaultHandlers = new CopyOnWriteArrayList<DefaultHandlerData>();
+ }
+
+ /**
+ * Registers the specified {@code DefaultParametersHandler} object for the
+ * given parameters class. This means that this handler object is invoked
+ * every time a parameters object of the specified class or one of its
+ * subclasses is initialized. The handler can set arbitrary default values
+ * for the properties supported by this parameters object. If there are
+ * multiple handlers registered supporting a specific parameters class, they
+ * are invoked in the order in which they were registered. So handlers
+ * registered later may override the values set by handlers registered
+ * earlier.
+ *
+ * @param <T> the type of the parameters supported by this handler
+ * @param paramsClass the parameters class supported by this handler (must
+ * not be <b>null</b>)
+ * @param handler the {@code DefaultParametersHandler} to be registered
+ * (must not be <b>null</b>)
+ * @throws IllegalArgumentException if a required parameter is missing
+ */
+ public <T> void registerDefaultsHandler(Class<T> paramsClass,
+ DefaultParametersHandler<? super T> handler)
+ {
+ registerDefaultsHandler(paramsClass, handler, null);
+ }
+
+ /**
+ * Registers the specified {@code DefaultParametersHandler} object for the
+ * given parameters class and start class in the inheritance hierarchy. This
+ * method works like
+ * {@link #registerDefaultsHandler(Class, DefaultParametersHandler)}, but
+ * the defaults handler is only executed on parameter objects that are
+ * instances of the specified start class. Parameter classes do not stand in
+ * a real inheritance hierarchy; however, there is a logic hierarchy defined
+ * by the methods supported by the different parameter objects. A properties
+ * parameter object for instance supports all methods defined for a
+ * file-based parameter object. So one can argue that
+ * {@link FileBasedBuilderParameters} is a base interface of
+ * {@link PropertiesBuilderParameters} (although, for technical reasons,
+ * this relation is not reflected in the Java classes). A
+ * {@link DefaultParametersHandler} object defined for a base interface can
+ * also deal with parameter objects "derived" from this base interface (i.e.
+ * supporting a super set of the methods defined by the base interface). Now
+ * there may be the use case that there is an implementation of
+ * {@code DefaultParametersHandler} for a base interface (e.g.
+ * {@code FileBasedBuilderParameters}), but it should only process specific
+ * derived interfaces (say {@code PropertiesBuilderParameters}, but not
+ * {@link XMLBuilderParameters}). This can be achieved by passing in
+ * {@code PropertiesBuilderParameters} as start class. In this case,
+ * {@code DefaultParametersManager} ensures that the handler is only called
+ * on parameter objects having both the start class and the actual type
+ * supported by the handler as base interfaces. The passed in start class
+ * can be <b>null</b>; then the parameter class supported by the handler is
+ * used (which is the default behavior of the
+ * {@link #registerDefaultsHandler(Class, DefaultParametersHandler)}
+ * method).
+ *
+ * @param <T> the type of the parameters supported by this handler
+ * @param paramsClass the parameters class supported by this handler (must
+ * not be <b>null</b>)
+ * @param handler the {@code DefaultParametersHandler} to be registered
+ * (must not be <b>null</b>)
+ * @param startClass an optional start class in the hierarchy of parameter
+ * objects for which this handler should be applied
+ * @throws IllegalArgumentException if a required parameter is missing
+ */
+ public <T> void registerDefaultsHandler(Class<T> paramsClass,
+ DefaultParametersHandler<? super T> handler, Class<?> startClass)
+ {
+ if (paramsClass == null)
+ {
+ throw new IllegalArgumentException(
+ "Parameters class must not be null!");
+ }
+ if (handler == null)
+ {
+ throw new IllegalArgumentException(
+ "DefaultParametersHandler must not be null!");
+ }
+ defaultHandlers.add(new DefaultHandlerData(handler, paramsClass,
+ startClass));
+ }
+
+ /**
+ * Removes the specified {@code DefaultParametersHandler} from this
+ * instance. If this handler has been registered multiple times for
+ * different start classes, all occurrences are removed.
+ *
+ * @param handler the {@code DefaultParametersHandler} to be removed
+ */
+ public void unregisterDefaultsHandler(DefaultParametersHandler<?> handler)
+ {
+ unregisterDefaultsHandler(handler, null);
+ }
+
+ /**
+ * Removes the specified {@code DefaultParametersHandler} from this instance
+ * if it is in combination with the given start class. If this handler has
+ * been registered multiple times for different start classes, only
+ * occurrences for the given start class are removed. The {@code startClass}
+ * parameter can be <b>null</b>, then all occurrences of the handler are
+ * removed.
+ *
+ * @param handler the {@code DefaultParametersHandler} to be removed
+ * @param startClass the start class for which this handler is to be removed
+ */
+ public void unregisterDefaultsHandler(DefaultParametersHandler<?> handler,
+ Class<?> startClass)
+ {
+ Collection<DefaultHandlerData> toRemove =
+ new LinkedList<DefaultHandlerData>();
+ for (DefaultHandlerData dhd : defaultHandlers)
+ {
+ if (dhd.isOccurrence(handler, startClass))
+ {
+ toRemove.add(dhd);
+ }
+ }
+
+ defaultHandlers.removeAll(toRemove);
+ }
+
+ /**
+ * Initializes the passed in {@code BuilderParameters} object by applying
+ * all matching {@link DefaultParametersHandler} objects registered at this
+ * instance. Using this method the passed in parameters object can be
+ * populated with default values.
+ *
+ * @param params the parameters object to be initialized (may be
+ * <b>null</b>, then this method has no effect)
+ */
+ public void initializeParameters(BuilderParameters params)
+ {
+ if (params != null)
+ {
+ for (DefaultHandlerData dhd : defaultHandlers)
+ {
+ dhd.applyHandlerIfMatching(params);
+ }
+ }
+ }
+
+ /**
+ * A data class storing information about {@code DefaultParametersHandler}
+ * objects added to a {@code Parameters} object. Using this class it is
+ * possible to find out which default handlers apply for a given parameters
+ * object and to invoke them.
+ */
+ private static class DefaultHandlerData
+ {
+ /** The handler object. */
+ private final DefaultParametersHandler<?> handler;
+
+ /** The class supported by this handler. */
+ private final Class<?> parameterClass;
+
+ /** The start class for applying this handler. */
+ private final Class<?> startClass;
+
+ /**
+ * Creates a new instance of {@code DefaultHandlerData}.
+ *
+ * @param h the {@code DefaultParametersHandler}
+ * @param cls the handler's data class
+ * @param startCls the start class
+ */
+ public DefaultHandlerData(DefaultParametersHandler<?> h, Class<?> cls,
+ Class<?> startCls)
+ {
+ handler = h;
+ parameterClass = cls;
+ startClass = startCls;
+ }
+
+ /**
+ * Checks whether the managed {@code DefaultParametersHandler} can be
+ * applied to the given parameters object. If this is the case, it is
+ * executed on this object and can initialize it with default values.
+ *
+ * @param obj the parameters object to be initialized
+ */
+ @SuppressWarnings("unchecked")
+ // There are explicit isInstance() checks, so there won't be
+ // ClassCastExceptions
+ public void applyHandlerIfMatching(BuilderParameters obj)
+ {
+ if (parameterClass.isInstance(obj)
+ && (startClass == null || startClass.isInstance(obj)))
+ {
+ @SuppressWarnings("rawtypes")
+ DefaultParametersHandler handlerUntyped = handler;
+ handlerUntyped.initializeDefaults(obj);
+ }
+ }
+
+ /**
+ * Tests whether this instance refers to the specified occurrence of a
+ * {@code DefaultParametersHandler}.
+ *
+ * @param h the handler to be checked
+ * @param startCls the start class
+ * @return <b>true</b> if this instance refers to this occurrence,
+ * <b>false</b> otherwise
+ */
+ public boolean isOccurrence(DefaultParametersHandler<?> h,
+ Class<?> startCls)
+ {
+ return h == handler
+ && (startCls == null || startCls.equals(startClass));
+ }
+ }
+}
Added: commons/proper/configuration/trunk/src/test/java/org/apache/commons/configuration/builder/TestDefaultParametersManager.java
URL: http://svn.apache.org/viewvc/commons/proper/configuration/trunk/src/test/java/org/apache/commons/configuration/builder/TestDefaultParametersManager.java?rev=1545824&view=auto
==============================================================================
--- commons/proper/configuration/trunk/src/test/java/org/apache/commons/configuration/builder/TestDefaultParametersManager.java (added)
+++ commons/proper/configuration/trunk/src/test/java/org/apache/commons/configuration/builder/TestDefaultParametersManager.java Tue Nov 26 20:34:06 2013
@@ -0,0 +1,269 @@
+/*
+ * 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.configuration.builder;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+
+import java.util.Map;
+
+import org.apache.commons.configuration.builder.fluent.FileBasedBuilderParameters;
+import org.apache.commons.configuration.builder.fluent.Parameters;
+import org.apache.commons.configuration.builder.fluent.PropertiesBuilderParameters;
+import org.apache.commons.configuration.builder.fluent.XMLBuilderParameters;
+import org.apache.commons.configuration.convert.ListDelimiterHandler;
+import org.apache.commons.configuration.tree.ExpressionEngine;
+import org.easymock.EasyMock;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+/**
+ * Test class for {@code DefaultParametersManager}.
+ *
+ * @version $Id: $
+ */
+public class TestDefaultParametersManager
+{
+ /** Constant for the default encoding. */
+ private static final String DEF_ENCODING = "UTF-8";
+
+ /** A test list delimiter handler. */
+ private static ListDelimiterHandler listHandler;
+
+ /** An object for creating new parameters objects. */
+ private Parameters parameters;
+
+ /** The manager to be tested. */
+ private DefaultParametersManager manager;
+
+ @BeforeClass
+ public static void setUpBeforeClass() throws Exception
+ {
+ listHandler = EasyMock.createMock(ListDelimiterHandler.class);
+ }
+
+ @Before
+ public void setUp() throws Exception
+ {
+ parameters = new Parameters();
+ manager = new DefaultParametersManager();
+ }
+
+ /**
+ * Tries to register a default handler without a class.
+ */
+ @Test(expected = IllegalArgumentException.class)
+ public void testRegisterDefaultsHandlerNoClass()
+ {
+ manager.registerDefaultsHandler(null, new FileBasedDefaultsHandler());
+ }
+
+ /**
+ * Tries to register a null default handler.
+ */
+ @Test(expected = IllegalArgumentException.class)
+ public void testRegisterDefaultsHandlerNoHandler()
+ {
+ manager.registerDefaultsHandler(BasicBuilderProperties.class, null);
+ }
+
+ /**
+ * Checks whether the expected default values have been set on a parameters
+ * object.
+ *
+ * @param map the map with parameters
+ */
+ private static void checkDefaultValues(Map<String, Object> map)
+ {
+ assertEquals("Wrong delimiter handler", listHandler,
+ map.get("listDelimiterHandler"));
+ assertEquals("Wrong exception flag value", Boolean.TRUE,
+ map.get("throwExceptionOnMissing"));
+ FileBasedBuilderParametersImpl fbparams =
+ FileBasedBuilderParametersImpl.fromParameters(map);
+ assertEquals("Wrong encoding", DEF_ENCODING, fbparams.getFileHandler()
+ .getEncoding());
+ }
+
+ /**
+ * Checks that no default values have been set on a parameters object.
+ *
+ * @param map the map with parameters
+ */
+ private static void checkNoDefaultValues(Map<String, Object> map)
+ {
+ assertFalse("Got base properties",
+ map.containsKey("throwExceptionOnMissing"));
+ FileBasedBuilderParametersImpl fbParams =
+ FileBasedBuilderParametersImpl.fromParameters(map, true);
+ assertNull("Got an encoding", fbParams.getFileHandler().getEncoding());
+ }
+
+ /**
+ * Tests whether default values are set for newly created parameters
+ * objects.
+ */
+ @Test
+ public void testApplyDefaults()
+ {
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ new FileBasedDefaultsHandler());
+ FileBasedBuilderParameters params = parameters.fileBased();
+ manager.initializeParameters(params);
+ Map<String, Object> map = params.getParameters();
+ checkDefaultValues(map);
+ }
+
+ /**
+ * Tests whether default values are also applied when a sub parameters class
+ * is created.
+ */
+ @Test
+ public void testApplyDefaultsOnSubClass()
+ {
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ new FileBasedDefaultsHandler());
+ XMLBuilderParameters params = parameters.xml();
+ manager.initializeParameters(params);
+ Map<String, Object> map = params.getParameters();
+ checkDefaultValues(map);
+ }
+
+ /**
+ * Tests that default values are only applied if the start class provided at
+ * registration time matches.
+ */
+ @Test
+ public void testApplyDefaultsStartClass()
+ {
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ new FileBasedDefaultsHandler(), XMLBuilderParameters.class);
+ XMLBuilderParameters paramsXml = parameters.xml();
+ manager.initializeParameters(paramsXml);
+ Map<String, Object> map = paramsXml.getParameters();
+ checkDefaultValues(map);
+ PropertiesBuilderParameters paramsProps = parameters.properties();
+ manager.initializeParameters(paramsProps);
+ map = paramsProps.getParameters();
+ checkNoDefaultValues(map);
+ }
+
+ /**
+ * Tests whether multiple handlers can be registered for the same classes
+ * and whether they are called in the correct order.
+ */
+ @Test
+ public void testApplyDefaultsMultipleHandlers()
+ {
+ final ExpressionEngine engine =
+ EasyMock.createMock(ExpressionEngine.class);
+ manager.registerDefaultsHandler(XMLBuilderParameters.class,
+ new DefaultParametersHandler<XMLBuilderParameters>()
+ {
+ public void initializeDefaults(
+ XMLBuilderParameters parameters)
+ {
+ parameters
+ .setThrowExceptionOnMissing(false)
+ .setListDelimiterHandler(
+ EasyMock.createMock(ListDelimiterHandler.class))
+ .setExpressionEngine(engine);
+ }
+ });
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ new FileBasedDefaultsHandler());
+ XMLBuilderParameters params = parameters.xml();
+ manager.initializeParameters(params);
+ Map<String, Object> map = params.getParameters();
+ checkDefaultValues(map);
+ assertSame("Expression engine not set", engine,
+ map.get("expressionEngine"));
+ }
+
+ /**
+ * Tests whether initializeParameters() ignores null input. (We can only
+ * test that no exception is thrown.)
+ */
+ @Test
+ public void testInitializeParametersNull()
+ {
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ new FileBasedDefaultsHandler());
+ manager.initializeParameters(null);
+ }
+
+ /**
+ * Tests whether all occurrences of a given defaults handler can be removed.
+ */
+ @Test
+ public void testUnregisterDefaultsHandlerAll()
+ {
+ FileBasedDefaultsHandler handler = new FileBasedDefaultsHandler();
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ handler, XMLBuilderParameters.class);
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ handler, PropertiesBuilderParameters.class);
+ manager.unregisterDefaultsHandler(handler);
+
+ XMLBuilderParameters paramsXml = parameters.xml();
+ manager.initializeParameters(paramsXml);
+ checkNoDefaultValues(paramsXml.getParameters());
+ PropertiesBuilderParameters paramsProps = parameters.properties();
+ manager.initializeParameters(paramsProps);
+ checkNoDefaultValues(paramsProps.getParameters());
+ }
+
+ /**
+ * Tests whether a specific occurrence of a defaults handler can be removed.
+ */
+ @Test
+ public void testUnregisterDefaultsHandlerSpecific()
+ {
+ FileBasedDefaultsHandler handler = new FileBasedDefaultsHandler();
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ handler, XMLBuilderParameters.class);
+ manager.registerDefaultsHandler(FileBasedBuilderParameters.class,
+ handler, PropertiesBuilderParameters.class);
+ manager.unregisterDefaultsHandler(handler,
+ PropertiesBuilderParameters.class);
+ XMLBuilderParameters paramsXml = parameters.xml();
+ manager.initializeParameters(paramsXml);
+ checkDefaultValues(paramsXml.getParameters());
+ PropertiesBuilderParameters paramsProps = parameters.properties();
+ manager.initializeParameters(paramsProps);
+ checkNoDefaultValues(paramsProps.getParameters());
+ }
+
+ /**
+ * A test defaults handler implementation for testing the initialization of
+ * parameters objects with default values. This class sets some hard-coded
+ * default values.
+ */
+ private static class FileBasedDefaultsHandler implements
+ DefaultParametersHandler<FileBasedBuilderParameters>
+ {
+ public void initializeDefaults(FileBasedBuilderParameters parameters)
+ {
+ parameters.setThrowExceptionOnMissing(true)
+ .setEncoding(DEF_ENCODING)
+ .setListDelimiterHandler(listHandler);
+ }
+ }
+}