Apache Solr - 检索数据

在本章中，我们将讨论如何使用 Java 客户端 API 检索数据。假设我们有一个名为 sample.csv 的 .csv 文档，内容如下。

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

您可以使用 post 命令在名为 sample_Solr 的核心下索引此数据。

[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 RetrievingData.java 的文件中。

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  { 
    //准备 Solr 客户端
    String urlString = "http://localhost:8983/Solr/my_core";
    SolrClient Solr = new HttpSolrClient.Builder(urlString).build();
    
    //准备 Solr 查询
    SolrQuery query = new SolrQuery();
    query.setQuery("*:*");
    
    //添加要检索的字段
    query.addField("*");
    
    //执行查询
    QueryResponse queryResponse = Solr.query(query);
    
    //存储查询结果
    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));
    
    //保存操作
    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}