Java tutorial
/* * Copyright 2015 Dmitry Ustalov * * 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 mtsar.api.csv; import com.google.common.collect.Sets; import mtsar.api.Stage; import mtsar.api.Task; import mtsar.api.sql.TaskDAO; import org.apache.commons.csv.CSVFormat; import org.apache.commons.csv.CSVParser; import org.apache.commons.csv.CSVRecord; import org.apache.commons.lang3.StringUtils; import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.Writer; import java.nio.charset.StandardCharsets; import java.sql.Timestamp; import java.util.*; import java.util.stream.StreamSupport; import static com.google.common.base.Preconditions.checkArgument; public final class TaskCSV { public static final CSVFormat FORMAT = CSVFormat.EXCEL.withHeader(); private static final String[] HEADER = { "id", "stage", "datetime", "tags", "type", "description", "answers" }; private static final Comparator<Task> ORDER = (t1, t2) -> t1.getId().compareTo(t2.getId()); public static Iterator<Task> parse(Stage stage, CSVParser csv) { final Set<String> header = csv.getHeaderMap().keySet(); checkArgument(!Sets.intersection(header, Sets.newHashSet(HEADER)).isEmpty(), "Unknown CSV header: %s", String.join(",", header)); return StreamSupport.stream(csv.spliterator(), false).map(row -> { final String id = row.isSet("id") ? row.get("id") : null; final String[] tags = row.isSet("tags") && !StringUtils.isEmpty(row.get("tags")) ? row.get("tags").split("\\|") : new String[0]; final String type = row.get("type"); final String description = row.isSet("description") ? row.get("description") : null; final String[] answers = row.isSet("answers") && !StringUtils.isEmpty(row.get("answers")) ? row.get("answers").split("\\|") : new String[0]; final String datetime = row.isSet("datetime") ? row.get("datetime") : null; return new Task.Builder().setId(StringUtils.isEmpty(id) ? null : Integer.valueOf(id)) .setStage(stage.getId()).addAllTags(Arrays.asList(tags)) .setDateTime(new Timestamp(StringUtils.isEmpty(datetime) ? System.currentTimeMillis() : Long.parseLong(datetime) * 1000L)) .setType(StringUtils.defaultIfEmpty(type, TaskDAO.TASK_TYPE_SINGLE)).setDescription(description) .addAllAnswers(Arrays.asList(answers)).build(); }).iterator(); } public static void write(Collection<Task> tasks, OutputStream output) throws IOException { try (final Writer writer = new OutputStreamWriter(output, StandardCharsets.UTF_8)) { final Iterable<String[]> iterable = () -> tasks.stream().sorted(ORDER) .map(task -> new String[] { Integer.toString(task.getId()), // id task.getStage(), // stage Long.toString(task.getDateTime().toInstant().getEpochSecond()), // datetime String.join("|", task.getTags()), // tags task.getType(), // type task.getDescription(), // description String.join("|", task.getAnswers()), // answers }).iterator(); FORMAT.withHeader(HEADER).print(writer).printRecords(iterable); } } }