RefProcessor.java

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package com.sun.jersey.server.linking.impl;

import com.sun.jersey.server.linking.el.LinkBuilder;
import java.net.URI;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import javax.ws.rs.core.UriInfo;

/**
 * Utility class that can inject links into {@link Link} annotated fields in
 * an entity.
 * @author mh124079
 */
public class RefProcessor<T> {

    private EntityDescriptor instanceDescriptor;

    public RefProcessor(Class<T> c) {
        instanceDescriptor = EntityDescriptor.getInstance(c);
    }

    /**
     * Inject any {@link Link} annotated fields in the supplied entity and
     * recursively process its fields.
     * @param entity the entity object returned by the resource method
     * @param uriInfo the uriInfo for the request
     */
    public void processLinks(T entity, UriInfo uriInfo) {
        Set<Object> processed = new HashSet<Object>();
        Object resource = uriInfo.getMatchedResources().get(0);
        processLinks(entity, resource, entity, processed, uriInfo);
    }

    /**
     * Inject any {@link Link} annotated fields in the supplied instance. Called
     * once for the entity and then recursively for each member and field.
     * @param entity
     * @param processed a list of already processed objects, used to break
     * recursion when processing circular references.
     * @param uriInfo
     */
    private void processLinks(Object entity, Object resource, Object instance, 
            Set<Object> processed, UriInfo uriInfo) {
        if (instance==null || processed.contains(instance))
            return; // ignore null properties and defeat circular references
        processed.add(instance);

        // Process any @Link annotated fields in entity
        for (RefFieldDescriptor linkField: instanceDescriptor.getLinkFields()) {
            if (LinkBuilder.evaluateCondition(linkField.getCondition(), entity, resource, instance)) {
                URI uri = LinkBuilder.buildURI(linkField, entity, resource, instance, uriInfo);
                linkField.setPropertyValue(instance, uri);
            }
        }

        // If entity is an array or collection then process members
        Class<?> instanceClass = instance.getClass();
        if (instanceClass.isArray() && Object[].class.isAssignableFrom(instanceClass)) {
            Object array[] = (Object[])instance;
            for (Object member: array) {
                processMember(entity, resource, member, processed, uriInfo);
            }
        } else if (instance instanceof Collection) {
            Collection collection = (Collection)instance;
            for (Object member: collection) {
                processMember(entity, resource, member, processed, uriInfo);
            }
        }

        // Recursively process all member fields
        for (FieldDescriptor member: instanceDescriptor.getNonLinkFields()) {
            processMember(entity, resource, member.getFieldValue(instance), processed, uriInfo);
        }
    }

    private void processMember(Object entity, Object resource, Object member, Set<Object> processed, UriInfo uriInfo) {
        if (member != null) {
            RefProcessor proc = new RefProcessor(member.getClass());
            proc.processLinks(entity, resource, member, processed, uriInfo);
        }
    }

}