上篇部落格記錄瞭如何用java呼叫api把資料寫入索引，這次記錄下如何搜尋。

一、準備資料

    String data1 = JsonUtil.model2Json(new Blog(1, "git簡介", "2016-06-19", "SVN與Git最主要的區別..."));
    String data2 = JsonUtil.model2Json(new Blog(2, "Java中泛型的介紹與簡單使用", "2016-06-19", "學習目標 掌握泛型的產生意義..."));
    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框架基礎", "2016-06-19", "Hibernate框架基礎..."));
    String data5 = JsonUtil.model2Json(new Blog(5, "Git基本知識git", "2016-06-19", "Shell是什麼..."));
    String data6 = JsonUtil.model2Json(new Blog(6, "C++基本知識", "2016-06-19", "Shell是什麼..."));
    String data7 = JsonUtil.model2Json(new Blog(7, "Mysql基本知識", "2016-06-19", "git是什麼..."));
 

二、查詢

一次查詢可分為下面四個步驟：

• 1.建立連線ElasticSearch服務的client. 
  索引在ElasticSearch伺服器上，進行索引的查詢首先要和伺服器建立連線，這是第一步。

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

• 2.建立QueryBuilder. 
  QueryBuilder可以設定單個欄位的查詢,也可以設定多個欄位的查詢. 
  e.g.1

  : 查詢title欄位中包含hibernate關鍵字的文件:

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

  e.g.2: 查詢title欄位或content欄位中包含git關鍵字的文件:

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

• 3.執行查詢 
  通過client設定查詢的index、type、query.返回一個SearchResponse物件：

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

• 4.處理查詢結果 
  SearchResponse物件的getHits()方法獲取查詢結果,返回一個SearchHits的集合，遍歷集合獲取查詢的文件資訊：

  SearchHits hits = response.getHits();
  

三、java程式碼實現

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條結果");
            }

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

    }

}

查詢結果：

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簡介, content=SVN與Git最主要的區別...}
score:0.17673586:   {posttime=2016-06-19, id=7, title=Mysql基本知識, content=git是什麼...}
score:0.049935166:  {posttime=2016-06-19, id=5, title=Git基本知識git, content=Shell是什麼...}

參考資料：