ElasticSearch Java Api -检索索引库

Posted 2020-07-29 esc_ai

上篇博客记录了如何用java调用api把数据写入索引，这次记录下如何搜索。

一、准备数据

---

    String data1 = JsonUtil.model2Json(new Blog(1, "git简介", "2016-06-19", "SVN与Git最主要的区别..."));
    String data2 = JsonUtil.model2Json(new Blog(2, "Java中泛型的介绍与简单使用", "2016-06-19", "学习目标 掌握泛型的产生意义..."));
    String data3 = JsonUtil.model2Json(new Blog(3, "SQL基本操作", "2016-06-19", "基本操作：CRUD ..."));
    String data4 = JsonUtil.model2Json(new Blog(4, "Hibernate框架基础", "2016-06-19", "Hibernate框架基础..."));
    String data5 = JsonUtil.model2Json(new Blog(5, "Git基本知识git", "2016-06-19", "Shell是什么..."));
    String data6 = JsonUtil.model2Json(new Blog(6, "C++基本知识", "2016-06-19", "Shell是什么..."));
    String data7 = JsonUtil.model2Json(new Blog(7, "mysql基本知识", "2016-06-19", "git是什么..."));

二、查询

一次查询可分为下面四个步骤：

• 1.创建连接ElasticSearch服务的client.
  索引在ElasticSearch服务器上，进行索引的查询首先要和服务器创建连接，这是第一步。

  Client client = TransportClient.builder().build()
              .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), 9300));
  

• 2.创建QueryBuilder.
  QueryBuilder可以设置单个字段的查询,也可以设置多个字段的查询.
  e.g.1: 查询title字段中包含hibernate关键字的文档:

  QueryBuilder qb1 = termQuery("title", "hibernate");
  

  e.g.2: 查询title字段或content字段中包含git关键字的文档:

  QueryBuilder qb2= QueryBuilders.multiMatchQuery("git", "title","content");
  

• 3.执行查询
  通过client设置查询的index、type、query.返回一个SearchResponse对象：

  SearchResponse response = client.prepareSearch("blog").setTypes("article").setQuery(qb2).execute()
              .actionGet();
  

• 4.处理查询结果
  SearchResponse对象的getHits()方法获取查询结果,返回一个SearchHits的集合，遍历集合获取查询的文档信息：

  SearchHits hits = response.getHits();
  

三、java代码实现

package cn.com.bropen.es;

import java.net.InetAddress;
import java.net.UnknownHostException;

import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.Client;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.transport.InetSocketTransportAddress;
import org.elasticsearch.index.query.MultiMatchQueryBuilder;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;

import static org.elasticsearch.index.query.QueryBuilders.*;

public class ElasticSearchGet {

    public static void main(String[] args) {
        // client startup
        try {
            Client client = TransportClient.builder().build()
                    .addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), 9300));

            QueryBuilder qb1 = termQuery("title", "hibernate");
            QueryBuilder qb2= QueryBuilders.multiMatchQuery("git", "title","content");


            SearchResponse response = client.prepareSearch("blog").setTypes("article").setQuery(qb2).execute()
                    .actionGet();

            SearchHits hits = response.getHits();
            if (hits.totalHits() > 0) {
                for (SearchHit hit : hits) {
                    System.out.println("score:"+hit.getScore()+":\\t"+hit.getSource());// .get("title")
                }
            } else {
                System.out.println("搜到0条结果");
            }

        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

    }

}

查询结果：

log4j:WARN No appenders could be found for logger (org.elasticsearch.plugins).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
score:0.5:  {posttime=2016-06-19, id=1, title=git简介, content=SVN与Git最主要的区别...}
score:0.17673586:   {posttime=2016-06-19, id=7, title=Mysql基本知识, content=git是什么...}
score:0.049935166:  {posttime=2016-06-19, id=5, title=Git基本知识git, content=Shell是什么...}

参考资料：

1. 分布式搜索elasticsearch java API 之（五）——搜索
2. GET API
3. elasticsearch中文指南–java-api
4. 高亮显示