Solr檢索數據

在本章中，我們將討論如何使用Java Client API檢索數據。假設有一個名為sample.csv的.csv文檔，其中包含以下內容。

001,9848022337,Hyderabad,Rajiv,Reddy
002,9848022338,Kolkata,Siddarth,Battacharya
003,9848022339,Delhi,Rajesh,Khanna

可以使用post命令在核心-solr_sample下對此數據編制索引。

[zaixian@ubuntu:/usr/local/solr]$ ./post -c solr_sample sample.csv

以下是向Apache Solr索引添加文檔的Java程式代碼。將此代碼保存在RetrievingData.java的檔中。

import java.io.IOException;

import org.apache.Solr.client.Solrj.SolrClient;
import org.apache.Solr.client.Solrj.SolrQuery;
import org.apache.Solr.client.Solrj.SolrServerException;
import org.apache.Solr.client.Solrj.impl.HttpSolrClient;
import org.apache.Solr.client.Solrj.response.QueryResponse;
import org.apache.Solr.common.SolrDocumentList;

public class RetrievingData {
   public static void main(String args[]) throws SolrServerException, IOException  {
      //Preparing the Solr client
      String urlString = "http://localhost:8983/Solr/my_core";
      SolrClient Solr = new HttpSolrClient.Builder(urlString).build();

      //Preparing Solr query
      SolrQuery query = new SolrQuery();
      query.setQuery("*:*");

      //Adding the field to be retrieved
      query.addField("*");

      //Executing the query
      QueryResponse queryResponse = Solr.query(query);

      //Storing the results of the query
      SolrDocumentList docs = queryResponse.getResults();
      System.out.println(docs);
      System.out.println(docs.get(0));
      System.out.println(docs.get(1));
      System.out.println(docs.get(2));

      //Saving the operations
      Solr.commit();
   }
}

通過在終端中執行以下命令編譯上述代碼 -

[zaixian@ubuntu:/usr/local/solr]$ javac RetrievingData.java
[zaixian@ubuntu:/usr/local/solr]$ java RetrievingData

執行上述命令後，將得到以下輸出。

{numFound = 3,start = 0,docs = [SolrDocument{id=001, phone = [9848022337],
city = [Hyderabad], first_name = [Rajiv], last_name = [Reddy],
_version_ = 1547262806014820352}, SolrDocument{id = 002, phone = [9848022338],
city = [Kolkata], first_name = [Siddarth], last_name = [Battacharya],

_version_ = 1547262806026354688}, SolrDocument{id = 003, phone = [9848022339],
city = [Delhi], first_name = [Rajesh], last_name = [Khanna],

_version_ = 1547262806029500416}]}

SolrDocument{id = 001, phone = [9848022337], city = [Hyderabad], first_name = [Rajiv],
last_name = [Reddy], _version_ = 1547262806014820352}

SolrDocument{id = 002, phone = [9848022338], city = [Kolkata], first_name = [Siddarth],
last_name = [Battacharya], _version_ = 1547262806026354688}

SolrDocument{id = 003, phone = [9848022339], city = [Delhi], first_name = [Rajesh],
last_name = [Khanna], _version_ = 1547262806029500416}