Java tutorial
/* * Licensed to ElasticSearch and Shay Banon under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. ElasticSearch licenses this * file to you 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 org.elasticsearch.index.mapper.selector; import org.apache.lucene.document.Document; import org.apache.lucene.document.StoredField; import org.apache.lucene.index.FieldInfo; import org.elasticsearch.common.lucene.document.BaseFieldVisitor; import org.elasticsearch.index.mapper.internal.RoutingFieldMapper; import org.elasticsearch.index.mapper.internal.SourceFieldMapper; import org.elasticsearch.index.mapper.internal.UidFieldMapper; import java.io.IOException; /** * An optimized field selector that loads just the uid and the routing. */ public class UidAndRoutingFieldVisitor extends BaseFieldVisitor { private String uid; private String routing; @Override public Document createDocument() { Document document = new Document(); if (uid != null) { document.add(new StoredField(UidFieldMapper.NAME, uid)); } if (routing != null) { document.add(new StoredField(SourceFieldMapper.NAME, routing)); } return document; } @Override public void reset() { uid = null; routing = null; } @Override public Status needsField(FieldInfo fieldInfo) throws IOException { if (RoutingFieldMapper.NAME.equals(fieldInfo.name)) { return Status.YES; } else if (UidFieldMapper.NAME.equals(fieldInfo.name)) { return Status.YES; } return uid != null && routing != null ? Status.STOP : Status.NO; } @Override public void stringField(FieldInfo fieldInfo, String value) throws IOException { if (RoutingFieldMapper.NAME.equals(fieldInfo.name)) { routing = value; } else if (UidFieldMapper.NAME.equals(fieldInfo.name)) { uid = value; } } public String uid() { return uid; } public String routing() { return routing; } @Override public String toString() { return "uid_and_routing"; } }