Java tutorial
/* * Copyright 2008-present MongoDB, 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://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.mongodb; import org.bson.BSONObject; import org.bson.BasicBSONCallback; import org.bson.types.BasicBSONList; import org.bson.types.ObjectId; import java.util.Collections; import java.util.Iterator; import java.util.List; /** * An implementation of DBCallback that decodes into a DBObject. */ public class DefaultDBCallback extends BasicBSONCallback implements DBCallback { private final DBObjectFactory objectFactory; /** * Creates a new DefaultDBCallback. If the Collection is null, it uses {@link DBCollectionObjectFactory} to create documents, otherwise * it uses the collection's object factory. * * @param collection an optionally null Collection that the documents created by this callback belong to. */ public DefaultDBCallback(final DBCollection collection) { if (collection != null) { this.objectFactory = collection.getObjectFactory(); } else { this.objectFactory = new DBCollectionObjectFactory(); } } @Override public BSONObject create() { return objectFactory.getInstance(); } @Override public BSONObject create(final boolean array, final List<String> path) { return array ? new BasicDBList() : objectFactory.getInstance(path != null ? path : Collections.<String>emptyList()); } @Override public void gotDBRef(final String name, final String namespace, final ObjectId id) { _put(name, new DBRef(namespace, id)); } @Override public Object objectDone() { String name = curName(); BSONObject document = (BSONObject) super.objectDone(); if (!(document instanceof BasicBSONList)) { Iterator<String> iterator = document.keySet().iterator(); if (iterator.hasNext() && iterator.next().equals("$ref") && iterator.hasNext() && iterator.next().equals("$id")) { _put(name, new DBRef((String) document.get("$db"), (String) document.get("$ref"), document.get("$id"))); } } return document; } public static final DBCallbackFactory FACTORY = new DBCallbackFactory() { @Override public DBCallback create(final DBCollection collection) { return new DefaultDBCallback(collection); } }; }