基于Elasticsearch的自定义评分算法扩展

实现思路：

重写评分方法，调整计算文档得分的过程，然后根据function_score或script_sort进行排序检索。

 

实现步骤：

1、新建java项目TestProject，引入Elasticsearch的jar包

2、新建package：es.testscript

3、新建类TestScriptFactory，继承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);

    }

}

 

4、新建类TestScript，假设计算double类型的得分，继承AbstractDoubleSearchScript，并重写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 {

    //客户端传递的参与动态计算得分的参数

    private String[] paramArray;

 

    /**

     * 构造函数 获取传入的参数

     *

     * @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，计算得分

     *

     * @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;

        }

        //根据传入的paramArray计算得分

        defaultReturnVal=defaultReturnVal+1000;

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

        return defaultReturnVal;

    }

}

 

5、打包输出jar文件TestProject.jar

6、将TestProject.jar拷贝至ES目录的lib下

7、修改ES配置文件elasticsearch.yml，添加：

script.native:

    mynativescript.type: es.testscript.TestScriptFactory

注：mynativescript为自定义的脚本别名。

8、重启ES服务

9、执行检索：function_score方式

{

  "query": {

    "function_score": {

      "query": {

        "match_all": {}

      },

      "functions": [

        {

          "script_score": {

            "script": "mynativescript",

            "lang": "native",

            "params": {

              "p1": 1,

              "fields": "p1,p2"

            }

          }

        }

      ]

    }

  }

}

10、执行检索：script_sort方式

{

  "query": {

    "match_all": {}

  },

  "sort": {

    "_script": {

      "script": "mynativescript",

      "lang": "native",

      "order": "asc",

      "type": "string",

      "params": {

        "p1": 1,

        "p2": 2,

        "p3": 3

      }

    }

  }

}

11、执行检索：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")

                 );

//获取请求的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对象

 QueryContainer mainQuery = null; 
 FunctionScoreQuery funcQuery = new FunctionScoreQuery();
 funcQuery.ScoreMode = FunctionScoreMode.Sum;
 funcQuery.BoostMode = FunctionBoostMode.Replace;
 funcQuery.MaxBoost = 1000.0f;
 IFunctionScoreFunction func = new FunctionScoreFunctionsDescriptor<DTOCarInfoIndexField>().ScriptScore(s => s.Lang("native").Script("mynativescript"));
 IList<IFunctionScoreFunction> list = new List<IFunctionScoreFunction>();
 list.Add(func);
 funcQuery.Functions = list;
 mainQuery &= funcQuery;