Java tutorial
/** * This file is part of Graylog Pipeline Processor. * * Graylog Pipeline Processor is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Graylog Pipeline Processor is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Graylog Pipeline Processor. If not, see <http://www.gnu.org/licenses/>. */ package org.graylog.plugins.pipelineprocessor.functions.dates; import org.graylog.plugins.pipelineprocessor.EvaluationContext; import org.graylog.plugins.pipelineprocessor.ast.functions.AbstractFunction; import org.graylog.plugins.pipelineprocessor.ast.functions.FunctionArgs; import org.graylog.plugins.pipelineprocessor.ast.functions.FunctionDescriptor; import org.graylog.plugins.pipelineprocessor.ast.functions.ParameterDescriptor; import org.joda.time.DateTime; import org.joda.time.DateTimeZone; import org.joda.time.format.DateTimeFormat; import org.joda.time.format.DateTimeFormatter; import static com.google.common.collect.ImmutableList.of; public class FormatDate extends AbstractFunction<String> { public static final String NAME = "format_date"; private final ParameterDescriptor<DateTime, DateTime> value; private final ParameterDescriptor<String, DateTimeFormatter> format; private final ParameterDescriptor<String, DateTimeZone> timeZoneParam; public FormatDate() { value = ParameterDescriptor.type("value", DateTime.class).description("The date to format").build(); format = ParameterDescriptor.string("format", DateTimeFormatter.class).transform(DateTimeFormat::forPattern) .description( "The format string to use, see http://www.joda.org/joda-time/apidocs/org/joda/time/format/DateTimeFormat.html") .build(); timeZoneParam = ParameterDescriptor.string("timezone", DateTimeZone.class).transform(DateTimeZone::forID) .optional().description("The timezone to apply to the date, defaults to UTC").build(); } @Override public String evaluate(FunctionArgs args, EvaluationContext context) { final DateTime dateTime = value.required(args, context); final DateTimeFormatter formatter = format.required(args, context); if (dateTime == null || formatter == null) { return null; } final DateTimeZone timeZone = timeZoneParam.optional(args, context).orElse(DateTimeZone.UTC); return formatter.withZone(timeZone).print(dateTime); } @Override public FunctionDescriptor<String> descriptor() { return FunctionDescriptor.<String>builder().name(NAME).returnType(String.class) .params(of(value, format, timeZoneParam)) .description("Formats a date using the given format string").build(); } }