Java tutorial
/* * Copyright 2011-2015 Amazon Technologies, Inc. * * 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://aws.amazon.com/apache2.0 * * This file 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 com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper; import java.lang.reflect.Method; import java.util.Collection; import java.util.HashMap; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.concurrent.locks.ReentrantReadWriteLock; import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock; import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock; import org.apache.http.annotation.GuardedBy; /** * Reflection assistant for {@link DynamoDBMapper} */ class DynamoDBReflector { /* * Several caches for performance. Collectively, they can make this class * over twice as fast. */ private final Map<Class<?>, Collection<Method>> getterCache = new HashMap<Class<?>, Collection<Method>>(); private final Map<Class<?>, Method> primaryHashKeyGetterCache = new HashMap<Class<?>, Method>(); private final Map<Class<?>, Method> primaryRangeKeyGetterCache = new HashMap<Class<?>, Method>(); /* * All caches keyed by a Method use the getter for a particular mapped * property */ private final Map<Method, Method> setterCache = new HashMap<Method, Method>(); @GuardedBy("readWriteLockAttrName") private final Map<Method, String> attributeNameCache = new HashMap<Method, String>(); private final Map<Method, Boolean> versionAttributeGetterCache = new HashMap<Method, Boolean>(); private final Map<Method, Boolean> autoGeneratedKeyGetterCache = new HashMap<Method, Boolean>(); private final ReentrantReadWriteLock readWriteLockAttrName = new ReentrantReadWriteLock(); private final ReadLock readLockAttrName = readWriteLockAttrName.readLock(); private final WriteLock writeLockAttrName = readWriteLockAttrName.writeLock(); /** * Returns the set of getter methods which are relevant when marshalling or * unmarshalling an object. */ Collection<Method> getRelevantGetters(Class<?> clazz) { synchronized (getterCache) { if (!getterCache.containsKey(clazz)) { List<Method> relevantGetters = findRelevantGetters(clazz); getterCache.put(clazz, relevantGetters); } return getterCache.get(clazz); } } static List<Method> findRelevantGetters(Class<?> clazz) { List<Method> relevantGetters = new LinkedList<Method>(); for (Method m : clazz.getMethods()) { if (isRelevantGetter(m)) { relevantGetters.add(m); } } return relevantGetters; } /** * Returns whether the method given is a getter method we should serialize / * deserialize to the service. The method must begin with "get" or "is", * have no arguments, belong to a class that declares its table, and not be * marked ignored. */ private static boolean isRelevantGetter(Method m) { return (m.getName().startsWith("get") || m.getName().startsWith("is")) && m.getParameterTypes().length == 0 && isDocumentType(m.getDeclaringClass()) && !ReflectionUtils.getterOrFieldHasAnnotation(m, DynamoDBIgnore.class); } private static boolean isDocumentType(Class<?> clazz) { return (clazz.getAnnotation(DynamoDBTable.class) != null) || (clazz.getAnnotation(DynamoDBDocument.class) != null); } /** * Returns the annotated {@link DynamoDBRangeKey} getter for the class * given, or null if the class doesn't have one. */ <T> Method getPrimaryRangeKeyGetter(Class<T> clazz) { synchronized (primaryRangeKeyGetterCache) { if (!primaryRangeKeyGetterCache.containsKey(clazz)) { Method rangeKeyMethod = null; for (Method method : getRelevantGetters(clazz)) { if (method.getParameterTypes().length == 0 && ReflectionUtils.getterOrFieldHasAnnotation(method, DynamoDBRangeKey.class)) { rangeKeyMethod = method; break; } } primaryRangeKeyGetterCache.put(clazz, rangeKeyMethod); } return primaryRangeKeyGetterCache.get(clazz); } } /** * Returns all annotated {@link DynamoDBHashKey} and * {@link DynamoDBRangeKey} getters for the class given, throwing an * exception if there isn't one. * * TODO: caching */ <T> Collection<Method> getPrimaryKeyGetters(Class<T> clazz) { List<Method> keyGetters = new LinkedList<Method>(); for (Method getter : getRelevantGetters(clazz)) { if (ReflectionUtils.getterOrFieldHasAnnotation(getter, DynamoDBHashKey.class) || ReflectionUtils.getterOrFieldHasAnnotation(getter, DynamoDBRangeKey.class)) { keyGetters.add(getter); } } return keyGetters; } /** * Returns the annotated {@link DynamoDBHashKey} getter for the class given, * throwing an exception if there isn't one. */ <T> Method getPrimaryHashKeyGetter(Class<T> clazz) { Method hashKeyMethod; synchronized (primaryHashKeyGetterCache) { if (!primaryHashKeyGetterCache.containsKey(clazz)) { for (Method method : getRelevantGetters(clazz)) { if (method.getParameterTypes().length == 0 && ReflectionUtils.getterOrFieldHasAnnotation(method, DynamoDBHashKey.class)) { primaryHashKeyGetterCache.put(clazz, method); break; } } } hashKeyMethod = primaryHashKeyGetterCache.get(clazz); } if (hashKeyMethod == null) { throw new DynamoDBMappingException( "Public, zero-parameter hash key property must be annotated with " + DynamoDBHashKey.class); } return hashKeyMethod; } /** * Returns the {@link DynamoDBTable} annotation of the class given, throwing * a runtime exception if it isn't annotated. */ <T> DynamoDBTable getTable(Class<T> clazz) { DynamoDBTable table = clazz.getAnnotation(DynamoDBTable.class); if (table == null) throw new DynamoDBMappingException("Class " + clazz + " must be annotated with " + DynamoDBTable.class); return table; } /** * Returns the attribute name corresponding to the given getter method. */ String getAttributeName(Method getter) { String attributeName; readLockAttrName.lock(); try { attributeName = attributeNameCache.get(getter); } finally { readLockAttrName.unlock(); } if (attributeName != null) return attributeName; DynamoDBHashKey hashKeyAnnotation = ReflectionUtils.getAnnotationFromGetterOrField(getter, DynamoDBHashKey.class); if (hashKeyAnnotation != null) { attributeName = hashKeyAnnotation.attributeName(); if (attributeName != null && attributeName.length() > 0) return cacheAttributeName(getter, attributeName); } DynamoDBIndexHashKey indexHashKey = ReflectionUtils.getAnnotationFromGetterOrField(getter, DynamoDBIndexHashKey.class); if (indexHashKey != null) { attributeName = indexHashKey.attributeName(); if (attributeName != null && attributeName.length() > 0) return cacheAttributeName(getter, attributeName); } DynamoDBRangeKey rangeKey = ReflectionUtils.getAnnotationFromGetterOrField(getter, DynamoDBRangeKey.class); if (rangeKey != null) { attributeName = rangeKey.attributeName(); if (attributeName != null && attributeName.length() > 0) return cacheAttributeName(getter, attributeName); } DynamoDBIndexRangeKey indexRangeKey = ReflectionUtils.getAnnotationFromGetterOrField(getter, DynamoDBIndexRangeKey.class); if (indexRangeKey != null) { attributeName = indexRangeKey.attributeName(); if (attributeName != null && attributeName.length() > 0) return cacheAttributeName(getter, attributeName); } DynamoDBAttribute attribute = ReflectionUtils.getAnnotationFromGetterOrField(getter, DynamoDBAttribute.class); if (attribute != null) { attributeName = attribute.attributeName(); if (attributeName != null && attributeName.length() > 0) return cacheAttributeName(getter, attributeName); } DynamoDBVersionAttribute version = ReflectionUtils.getAnnotationFromGetterOrField(getter, DynamoDBVersionAttribute.class); if (version != null) { attributeName = version.attributeName(); if (attributeName != null && attributeName.length() > 0) return cacheAttributeName(getter, attributeName); } // Default to the camel-cased field name of the getter method, inferred // according to the Java naming convention. attributeName = ReflectionUtils.getFieldNameByGetter(getter, true); return cacheAttributeName(getter, attributeName); } private String cacheAttributeName(Method getter, String attributeName) { writeLockAttrName.lock(); try { attributeNameCache.put(getter, attributeName); } finally { writeLockAttrName.unlock(); } return attributeName; } /** * Returns the setter corresponding to the getter given, or null if no such * setter exists. */ Method getSetter(Method getter) { synchronized (setterCache) { if (!setterCache.containsKey(getter)) { String fieldName = ReflectionUtils.getFieldNameByGetter(getter, false); String setterName = "set" + fieldName; Method setter = null; try { setter = getter.getDeclaringClass().getMethod(setterName, getter.getReturnType()); } catch (NoSuchMethodException e) { throw new DynamoDBMappingException("Expected a public, one-argument method called " + setterName + " on class " + getter.getDeclaringClass(), e); } catch (SecurityException e) { throw new DynamoDBMappingException("No access to public, one-argument method called " + setterName + " on class " + getter.getDeclaringClass(), e); } setterCache.put(getter, setter); } return setterCache.get(getter); } } /** * Returns whether the method given is an annotated, no-args getter of a * version attribute. */ boolean isVersionAttributeGetter(Method getter) { synchronized (versionAttributeGetterCache) { if (!versionAttributeGetterCache.containsKey(getter)) { versionAttributeGetterCache.put(getter, getter.getName().startsWith("get") && getter.getParameterTypes().length == 0 && ReflectionUtils.getterOrFieldHasAnnotation(getter, DynamoDBVersionAttribute.class)); } return versionAttributeGetterCache.get(getter); } } /** * Returns whether the method given is an assignable key getter. */ boolean isAssignableKey(Method getter) { synchronized (autoGeneratedKeyGetterCache) { if (!autoGeneratedKeyGetterCache.containsKey(getter)) { autoGeneratedKeyGetterCache.put(getter, ReflectionUtils.getterOrFieldHasAnnotation(getter, DynamoDBAutoGeneratedKey.class) && (ReflectionUtils.getterOrFieldHasAnnotation(getter, DynamoDBHashKey.class) || ReflectionUtils.getterOrFieldHasAnnotation(getter, DynamoDBRangeKey.class))); } return autoGeneratedKeyGetterCache.get(getter); } } /** * Returns the name of the primary hash key. */ String getPrimaryHashKeyName(Class<?> clazz) { return getAttributeName(getPrimaryHashKeyGetter(clazz)); } /** * Returns the name of the primary range key, or null if the table does not * one. */ String getPrimaryRangeKeyName(Class<?> clazz) { Method primaryRangeKeyGetter = getPrimaryHashKeyGetter(clazz); return primaryRangeKeyGetter == null ? null : getAttributeName(getPrimaryRangeKeyGetter(clazz)); } /** * Returns true if and only if the specified class has declared a * primary range key. */ boolean hasPrimaryRangeKey(Class<?> clazz) { return getPrimaryRangeKeyGetter(clazz) != null; } }