基於Elasticsearch的自定義評分算法擴展 (轉)

實現思路：

重寫評分方法，調整計算文檔得分的過程，而後根據function_score或script_sort進行排序檢索。

 

實現步驟：

一、新建java項目TestProject，引入Elasticsearch的jar包

二、新建package：es.testscript

三、新建類TestScriptFactory，繼承NativeScriptFactory，示例：

package es.testscript;

import java.util.Map;

 

import org.elasticsearch.common.Nullable;

import org.elasticsearch.script.ExecutableScript;

import org.elasticsearch.script.NativeScriptFactory;

 

/**

 * Created by lijunhao on 2016/3/29.

 */

public class TestScriptFactory implements NativeScriptFactory {

    @Override

    public ExecutableScript newScript(@Nullable Map<String, Object> params) {

        return new TestScript(params);

    }

}

 

四、新建類TestScript，假設計算double類型的得分，繼承AbstractDoubleSearchScript，並重寫runAsDouble方法，示例：

package es.testscript;

 

import java.util.Iterator;

import java.util.Map;

import java.util.Set;

 

import org.elasticsearch.common.Nullable;

import org.elasticsearch.index.fielddata.ScriptDocValues;

import org.elasticsearch.script.AbstractDoubleSearchScript;

import org.elasticsearch.script.AbstractLongSearchScript;

 

import java.util.Map;

 

public class TestScript extends AbstractDoubleSearchScript {

    //客戶端傳遞的參與動態計算得分的參數

    private String[] paramArray;

 

    /**

     * 構造函數 獲取傳入的參數

     *

     * @param params

     */

    public TestScript(@Nullable Map<String, Object> params) {

        if (params == null || params.size() == 0) {

            return;

        }

        Set<String> keys = params.keySet();

        Iterator<String> iterator = keys.iterator();

        while (iterator.hasNext()) {

            String key = iterator.next();

            String val = params.get(key).toString();

            System.out.println("key:" + key + " val:" + val + "\r\n");

        }

        if (params.get("fields") == null) {

            return;

        }

        paramArray = params.get("fields").toString().split(",");

        System.out.println("fields:" + params.get("fields").toString() + "\r\n");

    }

 

    /**

     * 排序方法，計算得分

     *

     * @return

     */

    @Override

    public double runAsDouble() {

        double defaultReturnVal = Double.parseDouble(String.valueOf(((ScriptDocValues.Longs)doc().get("id")).getValue()));

        if (paramArray == null || paramArray.length == 0) {

            return defaultReturnVal;

        }

        //根據傳入的paramArray計算得分

        defaultReturnVal=defaultReturnVal+1000;

        System.out.println("score:" + defaultReturnVal + "\r\n");

        return defaultReturnVal;

    }

}

 

五、打包輸出jar文件TestProject.jar

六、將TestProject.jar拷貝至ES目錄的lib下

七、修改ES配置文件elasticsearch.yml，添加：

script.native:

    mynativescript.type: es.testscript.TestScriptFactory

注：mynativescript爲自定義的腳本別名。

八、重啓ES服務

九、執行檢索：function_score方式

{

  "query": {

    "function_score": {

      "query": {

        "match_all": {}

      },

      "functions": [

        {

          "script_score": {

            "script": "mynativescript",

            "lang": "native",

            "params": {

              "p1": 1,

              "fields": "p1,p2"

            }

          }

        }

      ]

    }

  }

}

十、執行檢索：script_sort方式

{

  "query": {

    "match_all": {}

  },

  "sort": {

    "_script": {

      "script": "mynativescript",

      "lang": "native",

      "order": "asc",

      "type": "string",

      "params": {

        "p1": 1,

        "p2": 2,

        "p3": 3

      }

    }

  }

}

十一、執行檢索：Nest方式之Linq

var s = new SearchDescriptor<ModelTest>().From(0).Size(20).MatchAll().SortScript(sort => sort

                     .Descending()

                     .Script("mynativescript")

                     .Descending()

                     .Params(p => p

                         .Add("p1", 1.1).Add("p2", 2.2)

                     )

                     .Language("native")

                     .Type("string")

                 );

//獲取請求的json字符串

string reqStr = Encoding.UTF8.GetString(client.Serializer.Serialize(s));

ISearchResponse<ModelTest> resp = client.Search<ModelTest>(s);

ModelTest[] result = resp.Documents.ToArray();

 

12. Nest方式之Query對象

 1 QueryContainer mainQuery = null; <br> FunctionScoreQuery funcQuery = new FunctionScoreQuery();
 2 funcQuery.ScoreMode = FunctionScoreMode.Sum;
 3 funcQuery.BoostMode = FunctionBoostMode.Replace;
 4 funcQuery.MaxBoost = 1000.0f;
 5 IFunctionScoreFunction func = new FunctionScoreFunctionsDescriptor<DTOCarInfoIndexField>().ScriptScore(s => s.Lang("native").Script("mynativescript"));
 6 IList<IFunctionScoreFunction> list = new List<IFunctionScoreFunction>();
 7 list.Add(func);
 8 funcQuery.Functions = list;
 9 mainQuery &= funcQuery;
10 
11