Apache Solr - 检索数据

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  简述

  在本章中，我们将讨论如何使用 Java Client API 检索数据。假设我们有一个名为 .csv 的文档sample.csv与以下内容。

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

  您可以在名为的核心下索引此数据sample_Solr使用post命令。

  
  [Hadoop@localhost bin]$ ./post -c Solr_sample sample.csv
  

  以下是将文档添加到 Apache Solr 索引的 Java 程序。将此代码保存在名为的文件中RetrievingData.java.

  
  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();         
     } 
  }
  

  通过在终端中执行以下命令来编译上述代码 -

  
  [Hadoop@localhost bin]$ javac RetrievingData 
  [Hadoop@localhost bin]$ java RetrievingData
  

  执行上述命令后，您将获得以下输出。

  
  {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}