ASP.NET Web API + Elasticsearch 6.x 快速做个全文搜索

一、Elasticsearch 的安装 

下载  MSI(https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.0.1.msi)安装文件，完成后双击安装，点下一步，全部默认设置。

二、运行 Elasticsearch

打开 cmd，输入

cd %PROGRAMFILES%ElasticElasticsearchin

回车，输入 

.elasticsearch.exe

回车

三、开发环境搭建

1、新建一个 webApi 工程

2、安装 NEST，用来连接 Elasticsearch

打开 NuGet 包管理器控制台，输入以下命令

Install-Package NEST -Version 6.0.1

注意安装时带上版本号，NEST 与 Elasticsearch 版本对应，这是个坑。

3、连接 Elasticsearch

新建一个连接类 ClientHelper.cs

 1 public class ClientHelper
 2 {
 3     private static ClientHelper clientHelper = null;
 4     // 默认索引
 5     public static string DEFAULT_INDEX = "resource";
 6     private ElasticClient Client()
 7     {
 8         var nodes = new Uri[]
 9         {
10             new Uri("http://127.0.0.1:9200")
11         };
12         var pool = new StaticConnectionPool(nodes);
13         var settings = new ConnectionSettings(pool)
14             .DefaultIndex(DEFAULT_INDEX)
15             .PrettyJson();
16             //.BasicAuthentication("elastic", "changeme");
17 
18         return new ElasticClient(settings);
19     }
20 
21     public static ElasticClient getInstance()
22     {
23         if(clientHelper==null){
24             clientHelper = new ClientHelper();
25         }
26         return clientHelper.Client();   
27     }
28 }

新建索引类 Resource.cs

1 [ElasticsearchType(Name = "resource", IdProperty = "ID")]
2 public class Resource
3 {
4     [Keyword(Name = "id")]
5     public string ID { get; set; }
6 
7     [Text(Name = "name")]
8     public string NAME { get; set; }
9 }

4、增删查改操作

新建一个 api 控制器 ESController.cs

 1 public class ESController : ApiController
 2 {
 3   // GET: api/ES/1
 4   // 按 id 查询单条记录
 5   public Resource Get(string id)
 6   {
 7       var client = ClientHelper.getInstance();
 8       var response = client.Get<Resource>(id, idx => idx.Index(ClientHelper.DEFAULT_INDEX));
 9       return response.Source;
10   } 
11      
12   // POST api/ES   
13   // 批量导入数据库数据
14   public string Post()
15   {
16       using (DataContext db = new DataContext())
17        {
18           var client = ClientHelper.getInstance();
19           List<Demo>  items= db.demo.ToList();
20           for (int i = 0; i < 100;i++ )
21           {
22              var item = items[i];
23              Resource mod = new Resource();
24              mod.ID = item.ID;
25              mod.NAME = item.NAME;
26              client.Index<Resource>(mod, idx => idx.Index(ClientHelper.DEFAULT_INDEX));
27           }
28       }
29       return "OK";
30    }
31 
32    // PUT api/ES/5
33    // 按 id 更新单条数据
34    public Result Put(string id)
35    {
36        var client = ClientHelper.getInstance();
37        var response = client.Update<Resource>(id, idx => idx.Index(ClientHelper.DEFAULT_INDEX));
38        return response.Result; 
39    }
40 
41     // DELETE api/ES/5
42     // 按 id 删除单条数据
43     public Result Delete(string id)
44     {
45       var client = ClientHelper.getInstance();
46       var response = client.Delete<Resource>(id, idx => idx.Index(ClientHelper.DEFAULT_INDEX));
47       return response.Result; 
48     }
49 }

另新建一个api 控制器 SearchController.cs 用来提供搜索服务

 1 public class SearchController : ApiController
 2 {
 3     // GET: api/Search/
 4     public List<IHit<Resource>> Get(string id)
 5     {
 6         var client = ClientHelper.getInstance();
 7         var modList = client.Search<Resource>(s => s
 8             .From(0)
 9             .Size(10)
10             .Query(q => q.Term(t => t.NAME, id))
11         );
12         return modList.Hits.ToList();
13     }
14 }

5、试一试

(1) 导入数据到 Elasticsearch

POST http://localhost:8389/api/es

(2) 查询 id 为 1 的记录

GET http://localhost:8389/api/es/1

(3) 更新 id 为 1 的记录

PUT http://localhost:8389/api/es/1

(4) 删除 id 为 1 的记录

DELETE http://localhost:8389/api/es/1

(5) 查询名字中带有 中 的记录

GET http://localhost:8389/api/Search/中

一个简单的全文索引服务就完成了！