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.builder;
018
019import org.springframework.batch.item.json.JsonItemReader;
020import org.springframework.batch.item.json.JsonObjectReader;
021import org.springframework.core.io.Resource;
022import org.springframework.util.Assert;
023import org.springframework.util.StringUtils;
024
025/**
026 * A builder for {@link JsonItemReader}.
027 *
028 * @param <T> type of the target item
029 *
030 * @author Mahmoud Ben Hassine
031 * @since 4.1
032 */
033public class JsonItemReaderBuilder<T> {
034
035        private JsonObjectReader<T> jsonObjectReader;
036
037        private Resource resource;
038
039        private String name;
040
041        private boolean strict = true;
042
043        private boolean saveState = true;
044
045        private int maxItemCount = Integer.MAX_VALUE;
046
047        private int currentItemCount;
048
049        /**
050         * Set the {@link JsonObjectReader} to use to read and map Json objects to domain objects.
051         * @param jsonObjectReader to use
052         * @return The current instance of the builder.
053         * @see JsonItemReader#setJsonObjectReader(JsonObjectReader)
054         */
055        public JsonItemReaderBuilder<T> jsonObjectReader(JsonObjectReader<T> jsonObjectReader) {
056                this.jsonObjectReader = jsonObjectReader;
057
058                return this;
059        }
060
061        /**
062         * The {@link Resource} to be used as input.
063         * @param resource the input to the reader.
064         * @return The current instance of the builder.
065         * @see JsonItemReader#setResource(Resource)
066         */
067        public JsonItemReaderBuilder<T> resource(Resource resource) {
068                this.resource = resource;
069
070                return this;
071        }
072
073        /**
074         * The name used to calculate the key within the
075         * {@link org.springframework.batch.item.ExecutionContext}. Required if
076         * {@link #saveState(boolean)} is set to true.
077         * @param name name of the reader instance
078         * @return The current instance of the builder.
079         * @see org.springframework.batch.item.ItemStreamSupport#setName(String)
080         */
081        public JsonItemReaderBuilder<T> name(String name) {
082                this.name = name;
083
084                return this;
085        }
086
087        /**
088         * Setting this value to true indicates that it is an error if the input
089         * does not exist and an exception will be thrown. Defaults to true.
090         * @param strict indicates the input resource must exist
091         * @return The current instance of the builder.
092         * @see JsonItemReader#setStrict(boolean)
093         */
094        public JsonItemReaderBuilder<T> strict(boolean strict) {
095                this.strict = strict;
096
097                return this;
098        }
099
100        /**
101         * Configure if the state of the {@link org.springframework.batch.item.ItemStreamSupport}
102         * should be persisted within the {@link org.springframework.batch.item.ExecutionContext}
103         * for restart purposes.
104         * @param saveState defaults to true
105         * @return The current instance of the builder.
106         */
107        public JsonItemReaderBuilder<T> saveState(boolean saveState) {
108                this.saveState = saveState;
109
110                return this;
111        }
112
113        /**
114         * Configure the max number of items to be read.
115         * @param maxItemCount the max items to be read
116         * @return The current instance of the builder.
117         * @see org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader#setMaxItemCount(int)
118         */
119        public JsonItemReaderBuilder<T> maxItemCount(int maxItemCount) {
120                this.maxItemCount = maxItemCount;
121
122                return this;
123        }
124
125        /**
126         * Index for the current item. Used on restarts to indicate where to start from.
127         * @param currentItemCount current index
128         * @return The current instance of the builder.
129         * @see org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader#setCurrentItemCount(int)
130         */
131        public JsonItemReaderBuilder<T> currentItemCount(int currentItemCount) {
132                this.currentItemCount = currentItemCount;
133
134                return this;
135        }
136
137        /**
138         * Validate the configuration and build a new {@link JsonItemReader}.
139         * @return a new instance of the {@link JsonItemReader}
140         */
141        public JsonItemReader<T> build() {
142                Assert.notNull(this.jsonObjectReader, "A json object reader is required.");
143                Assert.notNull(this.resource, "A resource is required.");
144                if (this.saveState) {
145                        Assert.state(StringUtils.hasText(this.name), "A name is required when saveState is set to true.");
146                }
147
148                JsonItemReader<T> reader = new JsonItemReader<>(this.resource, this.jsonObjectReader);
149                reader.setName(this.name);
150                reader.setStrict(this.strict);
151                reader.setSaveState(this.saveState);
152                reader.setMaxItemCount(this.maxItemCount);
153                reader.setCurrentItemCount(this.currentItemCount);
154
155                return reader;
156        }
157}