Elasticsearch 之（48） Java API 基于scroll实现月度销售数据批量下载

比如说，现在要下载大批量的数据，从es，放到excel中，我们说，月度，或者年度，销售记录，很多，比如几千条，几万条，几十万条

其实就要用到我们之前《 Elasticsearch 之（5）kibana多种搜索方式》中讲解的es scroll api，对大量数据批量的获取和处理

就是要看宝马的销售记录

2条数据，做一个演示，每个批次下载一条宝马的销售记录，分2个批次给它下载完

package com.es.app;


import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.action.get.MultiGetItemResponse;
import org.elasticsearch.action.get.MultiGetResponse;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.InetSocketTransportAddress;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.transport.client.PreBuiltTransportClient;

import java.net.InetAddress;

public class ScrollCarInfoApp {

    public static void main(String[] args) throws Exception {
        Settings settings = Settings.builder()
                .put("cluster.name", "elasticsearch")
                .put("client.transport.sniff", true)
                .build();

        TransportClient client = new PreBuiltTransportClient(settings)
                .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("localhost"), 9300));

        SearchResponse searchResponse = client.prepareSearch("car_shop")
                .setTypes("sales")
                .setQuery(QueryBuilders.termQuery("brand.keyword", "宝马"))
                .setScroll(new TimeValue(60000))
                .setSize(1)
                .get();

        int batchCount = 0;

        do {
            for(SearchHit searchHit : searchResponse.getHits().getHits()) {
                System.out.println("batch: " + ++batchCount);
                System.out.println(searchHit.getSourceAsString());
                // 每次查询一批数据，比如1000行，然后写入本地的一个excel文件中
                // 如果说你一下子查询几十万条数据，不现实，jvm内存可能都会爆掉
            }

            searchResponse = client.prepareSearchScroll(searchResponse.getScrollId())
                    .setScroll(new TimeValue(60000))
                    .execute()
                    .actionGet();
        } while(searchResponse.getHits().getHits().length != 0);

        client.close();
    }

}

batch: 1
{
    "brand": "宝马",
    "name": "宝马320",
    "price": 320000,
    "produce_date": "2017-01-01",
    "sale_price": 280000,
    "sale_date": "2017-01-25"
}

batch: 2
{
    "brand": "宝马",
    "name": "宝马310",
    "price": 320000,
    "produce_date": "2017-01-01",
    "sale_price": 280000,
    "sale_date": "2017-01-25"
}