com.jayway.jaxrs.hateoas.support.FieldPath.java Source code

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Here is the source code for com.jayway.jaxrs.hateoas.support.FieldPath.java

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/*
 * Copyright 2011 the original author or authors.
 * 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.
 */

package com.jayway.jaxrs.hateoas.support;

import com.google.common.base.Function;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import com.jayway.jaxrs.hateoas.HateoasInjectException;
import com.jayway.jaxrs.hateoas.HateoasLinkInjector;
import com.jayway.jaxrs.hateoas.HateoasVerbosity;
import com.jayway.jaxrs.hateoas.LinkProducer;
import org.apache.commons.lang.StringUtils;

import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;

/**
 * @author Mattias Hellborg Arthursson
 * @author Kalle Stenflo
 */
public class FieldPath implements Iterable<String> {
    public final static FieldPath EMPTY_PATH = new FieldPath(Collections.<String>emptyList());

    private final Collection<String> path;

    private FieldPath(Collection<String> path) {
        this.path = path;

        for (String s : path) {
            if (StringUtils.isBlank(s)) {
                throw new IllegalArgumentException("Blank elements in field path are not allowed");
            }
        }
    }

    public static FieldPath path(String path) {
        String[] pathElement = path.split("\\.");
        return new FieldPath(Arrays.asList(pathElement));
    }

    @Override
    public Iterator<String> iterator() {
        return path.iterator();
    }

    public Object injectLinks(Object target, HateoasLinkInjector<Object> injector, LinkProducer linkProducer,
            HateoasVerbosity verbosity) {

        if (target == null) {
            return target;
        }
        try {
            return injectLinks(iterator(), target, injector, linkProducer, verbosity);
        } catch (Exception e) {
            throw new HateoasInjectException(e);
        }
    }

    @SuppressWarnings("unchecked")
    private Object injectLinks(Iterator<String> pathIterator, Object currentTarget,
            final HateoasLinkInjector<Object> injector, final LinkProducer linkProducer,
            final HateoasVerbosity verbosity) throws NoSuchFieldException, IllegalAccessException {

        if (currentTarget == null) {
            return currentTarget;
        }

        if (!pathIterator.hasNext()) {
            if (Collection.class.isAssignableFrom(currentTarget.getClass())) {
                Collection<Object> targetAsCollection = (Collection<Object>) currentTarget;
                return Collections2.transform(targetAsCollection, new Function<Object, Object>() {
                    @Override
                    public Object apply(Object entry) {
                        return injector.injectLinks(entry, linkProducer, verbosity);
                    }
                });
            }
            return injector.injectLinks(currentTarget, linkProducer, verbosity);
        }

        String currentFieldName = pathIterator.next();
        Field currentField = ReflectionUtils.getField(currentTarget, currentFieldName);

        Object nextTarget = currentField.get(currentTarget);
        Object nextResult = null;
        if (nextTarget != null && Collection.class.isAssignableFrom(nextTarget.getClass())) {
            // We have not yet arrived at the end of the FieldPath, and the object at the current position in the
            // path is a Collection - the rest of the path should be traversed for _each_ of the items in the
            // collection.
            final ImmutableList<String> restOfPath = ImmutableList.copyOf(pathIterator);
            Collection<Object> targetAsCollection = (Collection<Object>) nextTarget;
            nextResult = Collections2.transform(targetAsCollection, new Function<Object, Object>() {
                @Override
                public Object apply(Object entry) {
                    FieldPath nestedPath = new FieldPath(restOfPath);
                    return nestedPath.injectLinks(entry, injector, linkProducer, verbosity);
                }
            });
        } else {
            nextResult = injectLinks(pathIterator, nextTarget, injector, linkProducer, verbosity);
        }
        //ReflectionUtils.setFieldAccessible(currentField);

        ReflectionUtils.setField(currentTarget, currentField.getName(), nextResult);

        return currentTarget;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        FieldPath fieldPath = (FieldPath) o;

        if (path != null ? !path.equals(fieldPath.path) : fieldPath.path != null)
            return false;

        return true;
    }

    @Override
    public int hashCode() {
        return path != null ? path.hashCode() : 0;
    }
}