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Diffstat (limited to 'feature-pooling-dmaap/src/main/java/org/onap/policy/drools/pooling/extractor/ClassExtractors.java')
| -rw-r--r-- | feature-pooling-dmaap/src/main/java/org/onap/policy/drools/pooling/extractor/ClassExtractors.java | 466 |
1 files changed, 466 insertions, 0 deletions
diff --git a/feature-pooling-dmaap/src/main/java/org/onap/policy/drools/pooling/extractor/ClassExtractors.java b/feature-pooling-dmaap/src/main/java/org/onap/policy/drools/pooling/extractor/ClassExtractors.java new file mode 100644 index 00000000..cb12a6ac --- /dev/null +++ b/feature-pooling-dmaap/src/main/java/org/onap/policy/drools/pooling/extractor/ClassExtractors.java @@ -0,0 +1,466 @@ +/* + * ============LICENSE_START======================================================= + * ONAP + * ================================================================================ + * Copyright (C) 2018 AT&T Intellectual Property. All rights reserved. + * ================================================================================ + * Licensed 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. + * ============LICENSE_END========================================================= + */ + +package org.onap.policy.drools.pooling.extractor; + +import java.lang.reflect.Field; +import java.lang.reflect.Method; +import java.util.Map; +import java.util.Properties; +import java.util.concurrent.ConcurrentHashMap; +import org.apache.commons.lang.StringUtils; +import org.onap.policy.drools.utils.Pair; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Extractors for each object class. Properties define how the data is to be + * extracted for a given class, where the properties are similar to the + * following: + * + * <pre> + * <code><a.prefix>.<class.name> = ${event.reqid}</code> + * </pre> + * + * If it doesn't find a property for the class, then it looks for a property for + * that class' super class or interfaces. Extractors are compiled and cached. + */ +public class ClassExtractors { + + private static final Logger logger = LoggerFactory.getLogger(ClassExtractors.class); + + /** + * Properties that specify how the data is to be extracted from a given + * class. + */ + private final Properties properties; + + /** + * Property prefix, including a trailing ".". + */ + private final String prefix; + + /** + * Type of item to be extracted. + */ + private final String type; + + /** + * Maps the class name to its extractor. + */ + private final ConcurrentHashMap<String, Extractor> class2extractor = new ConcurrentHashMap<>(); + + /** + * + * @param props properties that specify how the data is to be extracted from + * a given class + * @param prefix property name prefix, prepended before the class name + * @param type type of item to be extracted + */ + public ClassExtractors(Properties props, String prefix, String type) { + this.properties = props; + this.prefix = (prefix.endsWith(".") ? prefix : prefix + "."); + this.type = type; + } + + /** + * Gets the number of extractors in the map. + * + * @return gets the number of extractors in the map + */ + protected int size() { + return class2extractor.size(); + } + + /** + * Extracts the desired data item from an object. + * + * @param object object from which to extract the data item + * @return the extracted item, or {@code null} if it could not be extracted + */ + public Object extract(Object object) { + if (object == null) { + return null; + } + + Extractor ext = getExtractor(object); + + return ext.extract(object); + } + + /** + * Gets the extractor for the given type of object, creating one if it + * doesn't exist yet. + * + * @param object object whose extracted is desired + * @return an extractor for the object + */ + private Extractor getExtractor(Object object) { + Class<?> clazz = object.getClass(); + Extractor ext = class2extractor.get(clazz.getName()); + + if (ext == null) { + // allocate a new extractor, if another thread doesn't beat us to it + ext = class2extractor.computeIfAbsent(clazz.getName(), xxx -> buildExtractor(clazz)); + } + + return ext; + } + + /** + * Builds an extractor for the class. + * + * @param clazz class for which the extractor should be built + * + * @return a new extractor + */ + private Extractor buildExtractor(Class<?> clazz) { + String value = properties.getProperty(prefix + clazz.getName(), null); + if (value != null) { + // property has config info for this class - build the extractor + return buildExtractor(clazz, value); + } + + /* + * Get the extractor, if any, for the super class or interfaces, but + * don't add one if it doesn't exist + */ + Extractor ext = getClassExtractor(clazz, false); + if (ext != null) { + return ext; + } + + /* + * No extractor defined for for this class or its super class - we + * cannot extract data items from objects of this type, so just + * allocated a null extractor. + */ + logger.warn("missing property " + prefix + clazz.getName()); + return new NullExtractor(); + } + + /** + * Builds an extractor for the class, based on the config value extracted + * from the corresponding property. + * + * @param clazz class for which the extractor should be built + * @param value config value (e.g., "${event.request.id}" + * @return a new extractor + */ + private Extractor buildExtractor(Class<?> clazz, String value) { + if (!value.startsWith("${")) { + logger.warn("property value for " + prefix + clazz.getName() + " does not start with '${'"); + return new NullExtractor(); + } + + if (!value.endsWith("}")) { + logger.warn("property value for " + prefix + clazz.getName() + " does not end with '}'"); + return new NullExtractor(); + } + + // get the part in the middle + String val = value.substring(2, value.length() - 1); + if (val.startsWith(".")) { + logger.warn("property value for " + prefix + clazz.getName() + " begins with '.'"); + return new NullExtractor(); + } + + if (val.endsWith(".")) { + logger.warn("property value for " + prefix + clazz.getName() + " ends with '.'"); + return new NullExtractor(); + } + + // everything's valid - create the extractor + try { + ComponetizedExtractor ext = new ComponetizedExtractor(clazz, val.split("[.]")); + + /* + * If there's only one extractor, then just return it, otherwise + * return the whole extractor. + */ + return (ext.extractors.length == 1 ? ext.extractors[0] : ext); + + } catch (ExtractorException e) { + logger.warn("cannot build extractor for " + clazz.getName()); + return new NullExtractor(); + } + } + + /** + * Gets the extractor for a class, examining all super classes and + * interfaces. + * + * @param clazz class whose extractor is desired + * @param addOk {@code true} if the extractor may be added, provided the + * property is defined, {@code false} otherwise + * @return the extractor to be used for the class, or {@code null} if no + * extractor has been defined yet + */ + private Extractor getClassExtractor(Class<?> clazz, boolean addOk) { + if (clazz == null) { + return null; + } + + Extractor ext = null; + + if (addOk) { + String val = properties.getProperty(prefix + clazz.getName(), null); + + if (val != null) { + /* + * A property is defined for this class, so create the extractor + * for it. + */ + return class2extractor.computeIfAbsent(clazz.getName(), xxx -> buildExtractor(clazz)); + } + } + + // see if the superclass has an extractor + if ((ext = getClassExtractor(clazz.getSuperclass(), true)) != null) { + return ext; + } + + // check the interfaces, too + for (Class<?> clz : clazz.getInterfaces()) { + if ((ext = getClassExtractor(clz, true)) != null) { + break; + } + } + + return ext; + } + + /** + * Extractor that always returns {@code null}. Used when no extractor could + * be built for a given object type. + */ + private class NullExtractor implements Extractor { + + @Override + public Object extract(Object object) { + logger.warn("cannot extract " + type + " from " + object.getClass()); + return null; + } + } + + /** + * Component-ized extractor. Extracts an object that is referenced + * hierarchically, where each name identifies a particular component within + * the hierarchy. Supports retrieval from {@link Map} objects, as well as + * via getXxx() methods, or by direct field retrieval. + * <p> + * Note: this will <i>not</i> work if POJOs are contained within a Map. + */ + private class ComponetizedExtractor implements Extractor { + + /** + * Extractor for each component. + */ + private final Extractor[] extractors; + + /** + * + * @param clazz the class associated with the object at the root of the + * hierarchy + * @param names name associated with each component + * @throws ExtractorException + */ + public ComponetizedExtractor(Class<?> clazz, String[] names) throws ExtractorException { + this.extractors = new Extractor[names.length]; + + Class<?> clz = clazz; + + for (int x = 0; x < names.length; ++x) { + String comp = names[x]; + + Pair<Extractor, Class<?>> pair = buildExtractor(clz, comp); + + extractors[x] = pair.first(); + clz = pair.second(); + } + } + + /** + * Builds an extractor for the given component of an object. + * + * @param clazz type of object from which the component will be + * extracted + * @param comp name of the component to extract + * @return a pair containing the extractor and the extracted object's + * type + * @throws ExtractorException + */ + private Pair<Extractor, Class<?>> buildExtractor(Class<?> clazz, String comp) throws ExtractorException { + Pair<Extractor, Class<?>> pair = null; + + if (pair == null) { + pair = getMethodExtractor(clazz, comp); + } + + if (pair == null) { + pair = getFieldExtractor(clazz, comp); + } + + if (pair == null) { + pair = getMapExtractor(clazz, comp); + } + + + // didn't find an extractor + if (pair == null) { + throw new ExtractorException("class " + clazz + " contains no element " + comp); + } + + return pair; + } + + @Override + public Object extract(Object object) { + Object obj = object; + + for (Extractor ext : extractors) { + if (obj == null) { + break; + } + + obj = ext.extract(obj); + } + + return obj; + } + + /** + * Gets an extractor that invokes a getXxx() method to retrieve the + * object. + * + * @param clazz container's class + * @param name name of the property to be retrieved + * @return a new extractor, or {@code null} if the class does not + * contain the corresponding getXxx() method + * @throws ExtractorException if the getXxx() method is inaccessible + */ + private Pair<Extractor, Class<?>> getMethodExtractor(Class<?> clazz, String name) throws ExtractorException { + Method meth; + + String nm = "get" + StringUtils.capitalize(name); + + try { + meth = clazz.getMethod(nm); + + Class<?> retType = meth.getReturnType(); + if (retType == void.class) { + // it's a void method, thus it won't return an object + return null; + } + + return new Pair<>(new MethodExtractor(meth), retType); + + } catch (NoSuchMethodException expected) { + // no getXxx() method, maybe there's a field by this name + return null; + + } catch (SecurityException e) { + throw new ExtractorException("inaccessible method " + clazz + "." + nm, e); + } + } + + /** + * Gets an extractor for a field within the object. + * + * @param clazz container's class + * @param name name of the field whose value is to be extracted + * @return a new extractor, or {@code null} if the class does not + * contain the given field + * @throws ExtractorException if the field is inaccessible + */ + private Pair<Extractor, Class<?>> getFieldExtractor(Class<?> clazz, String name) throws ExtractorException { + + Field field = getClassField(clazz, name); + if (field == null) { + return null; + } + + return new Pair<>(new FieldExtractor(field), field.getType()); + } + + /** + * Gets an extractor for an item within a Map object. + * + * @param clazz container's class + * @param key item key within the map + * @return a new extractor, or {@code null} if the class is not a Map + * subclass + * @throws ExtractorException + */ + private Pair<Extractor, Class<?>> getMapExtractor(Class<?> clazz, String key) throws ExtractorException { + + if (!Map.class.isAssignableFrom(clazz)) { + return null; + } + + /* + * Don't know the value's actual type, so we'll assume it's a Map + * for now. Things should still work OK, as this is only used to + * direct the constructor on what type of extractor to create next. + * If the object turns out not to be a map, then the MapExtractor + * for the next component will just return null. + */ + return new Pair<>(new MapExtractor(key), Map.class); + } + + /** + * Gets field within a class, examining all super classes and + * interfaces. + * + * @param clazz class whose field is desired + * @param name name of the desired field + * @return the field within the class, or {@code null} if the field does + * not exist + * @throws ExtractorException if the field is inaccessible + */ + private Field getClassField(Class<?> clazz, String name) throws ExtractorException { + if (clazz == null) { + return null; + } + + try { + return clazz.getDeclaredField(name); + + } catch (NoSuchFieldException expected) { + // no field by this name - try super class & interfaces + + } catch (SecurityException e) { + throw new ExtractorException("inaccessible field " + clazz + "." + name, e); + } + + + Field field; + + // see if the superclass has an extractor + if ((field = getClassField(clazz.getSuperclass(), name)) != null) { + return field; + } + + // not necessary to check the interfaces + + return field; + } + } +} |