001/*
002 * Copyright 2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *       https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.batch.item.json;
018
019import org.springframework.core.io.Resource;
020import org.springframework.lang.Nullable;
021
022/**
023 * Strategy interface for Json readers. Implementations are expected to use
024 * a streaming API in order to read Json objects one at a time.
025 *
026 * @param <T> type of the target object
027 *
028 * @author Mahmoud Ben Hassine
029 * @since 4.1
030 */
031public interface JsonObjectReader<T> {
032
033        /**
034         * Open the Json resource for reading.
035         * @param resource the input resource
036         * @throws Exception if unable to open the resource
037         */
038        default void open(Resource resource) throws Exception {
039
040        }
041
042        /**
043         * Read the next object in the Json resource if any.
044         * @return the next object or {@code null} if the resource is exhausted
045         * @throws Exception if unable to read the next object
046         */
047        @Nullable
048        T read() throws Exception;
049
050        /**
051         * Close the input resource.
052         * @throws Exception if unable to close the input resource
053         */
054        default void close() throws Exception {
055
056        }
057}