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package org.glassfish.jersey.message.filtering.spi;
import java.lang.annotation.Annotation;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import javax.inject.Inject;
import org.glassfish.jersey.internal.guava.Cache;
import org.glassfish.jersey.internal.guava.CacheBuilder;
/**
* Common implementation of {@link ObjectProvider object provider} and {@link ObjectGraphTransformer object graph transformer}.
* <p>
* Extensions of this class must provide a type of entity-filtering object (via generic type parameter) the requesting provider
* (e.g. message body worker) is familiar with and an implementation of
* {@link ObjectGraphTransformer#transform(ObjectGraph)} method for this type.
* </p>
*
* @param <T> representation of entity data filtering requested by provider.
* @author Michal Gajdos
*/
public abstract class AbstractObjectProvider<T> implements ObjectProvider<T>, ObjectGraphTransformer<T> {
private static final int PROVIDER_CACHE_SIZE = 1000;
private final Cache<EntityContext, T> filteringObjects = CacheBuilder.newBuilder().maximumSize(PROVIDER_CACHE_SIZE).build();
@Inject
private ScopeProvider scopeProvider;
@Inject
private EntityInspector entityInspector;
@Inject
private EntityGraphProvider graphProvider;
@Override
public final T getFilteringObject(final Type genericType, final boolean forWriter, final Annotation... annotations) {
return getFilteringObject(FilteringHelper.getEntityClass(genericType), forWriter, annotations);
}
private T getFilteringObject(final Class<?> entityClass, final boolean forWriter, final Annotation... annotations) {
if (FilteringHelper.filterableEntityClass(entityClass)) {
// Inspect.
entityInspector.inspect(entityClass, forWriter);
// Obtain runtime/resource scope.
final Set<String> filteringScope = scopeProvider.getFilteringScopes(getEntityAnnotations(annotations), true);
// Look into the cache.
final EntityContext entityContext = new EntityContext(entityClass, filteringScope);
T filteringObject = filteringObjects.getIfPresent(entityContext);
// Create new if not available.
if (filteringObject == null) {
filteringObject = createFilteringObject(entityClass, filteringScope, forWriter);
filteringObjects.put(entityContext, filteringObject);
}
return filteringObject;
}
return null;
}
/**
* Get entity annotations passed to request/response. This method filters annotations that are proxy instances (proxy
* annotations are taken from resource method and passed in this list).
*
* @param annotations annotations obtained from provider.
* @return annoations passed to request/response.
*/
private Annotation[] getEntityAnnotations(final Annotation[] annotations) {
final ArrayList<Annotation> entityAnnotations = new ArrayList<>();
for (final Annotation annotation : annotations) {
if (!(annotation instanceof Proxy)) {
entityAnnotations.add(annotation);
}
}
return entityAnnotations.toArray(new Annotation[entityAnnotations.size()]);
}
/**
* Create entity-filtering object after this object has not been found in the cache.
*
* @param entityClass entity class the entity-filtering object should be created for.
* @param filteringScopes entity-filtering scopes to create the entity-filtering object for.
* @param forWriter flag determining whether the class should be examined for reader or writer.
* @return entity-filtering object.
*/
private T createFilteringObject(final Class<?> entityClass, final Set<String> filteringScopes, final boolean forWriter) {
// Obtain the filtering object.
return transform(graphProvider.createObjectGraph(entityClass, filteringScopes, forWriter));
}
/**
* A helper method for a creation of an immutable set based on a provided set together with a given item.
*
* @param set The set to create the immutable set from.
* @param item The item to add to the set before it's made immutable.
* @return The immutable set from given set and item.
*/
protected Set<String> immutableSetOf(final Set<String> set, final String item) {
final Set<String> duplicate = new HashSet<>(set);
duplicate.add(item);
return Collections.unmodifiableSet(duplicate);
}
/**
* Creates a string identifier of a sub-graph.
*
* @param parent The parent class.
* @param field The field name.
* @param fieldClass The class of the field.
* @return The string identifier of the sub-graph.
*/
protected String subgraphIdentifier(final Class<?> parent, final String field, final Class<?> fieldClass) {
return parent.getName() + "_" + field + "_" + fieldClass.getName();
}
/**
* Class to be used as a key in cache ({@code EntityContext} -> filtering object) when processing similar requests.
*/
private static final class EntityContext {
private final Class<?> entityClass;
private final Set<String> filteringContext;
/**
* Create entity context class for given entity class and set of entity-filtering scopes.
*
* @param entityClass entity class.
* @param filteringScopes entity-filtering scopes.
*/
private EntityContext(final Class<?> entityClass, final Set<String> filteringScopes) {
this.entityClass = entityClass;
this.filteringContext = filteringScopes;
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if (!(o instanceof EntityContext)) {
return false;
}
final EntityContext that = (EntityContext) o;
return entityClass.equals(that.entityClass) && filteringContext.equals(that.filteringContext);
}
@Override
public int hashCode() {
int result = entityClass.hashCode();
result = 47 * result + filteringContext.hashCode();
return result;
}
}
}