Elasticsearch自定排序插件实现

Elasticsearch自定排序插件实现

本文将介绍以插件的形式实现Elasticsearch自定义排序。

整个插件项目的结构为

project
--src
----main
--------assemblies
------------plugin.xml
--------java
------------com.dcharm.plugin
----------------NativeScriptPlugin.java
----------------JyhBaseScriptFactory.java
--------resources
------------es-plugin.properties
----test
--pom.xml

下面会介绍各个文件的内容
1.pom.xml
pom.xml添加对Elasticsearch并且设置打包的方式，打包的方式引用了plugin.xml

   <dependencies>
       <dependency>
           <groupId>org.elasticsearch</groupId>
           <artifactId>elasticsearch</artifactId>
           <version>${es.version}</version>
           <scope>compile</scope>
       </dependency>
  </dependencies>
<build>
       <plugins>
           <plugin>
               <artifactId>maven-assembly-plugin</artifactId>
               <version>2.3</version>
               <configuration>
                   <appendAssemblyId>false</appendAssemblyId>
                   <outputDirectory>${project.build.directory}/releases/</outputDirectory>
                   <descriptors>
                       <descriptor>${basedir}/src/main/assemblies/plugin.xml</descriptor>
                   </descriptors>
               </configuration>
               <executions>
                   <execution>
                       <phase>package</phase>
                       <goals>
                           <goal>single</goal>
                       </goals>
                   </execution>
               </executions>
           </plugin>
       </plugins>
   </build>

2.plugin.xml
plugin.xml指定了插件打包的方式

<?xmlversion="1.0"?>
<assembly>
    <id>plugin</id>
    <formats>
        <format>zip</format>
    </formats>
    <includeBaseDirectory>false</includeBaseDirectory>
    <dependencySets>
        <dependencySet>
            <outputDirectory>/</outputDirectory>
            <useProjectArtifact>true</useProjectArtifact>
            <useTransitiveFiltering>true</useTransitiveFiltering>
            <excludes>
                <exclude>org.elasticsearch:elasticsearch</exclude>
            </excludes>
        </dependencySet>
    </dependencySets>
</assembly>

3.NativeScriptPlugin类

publicclassNativeScriptPlugin extendsAbstractPlugin {
    @Override
    publicString name() {
        return"native-script";//native-script为插件的名称
    }

    @Override
    publicString description() {
        return"native scripts";
    }

    publicvoidonModule(ScriptModule module) {
        //m2c_jyh_default就是排序算法的名称
        module.registerScript("m2c_jyh_default", JyhBaseScriptFactory.class);
    }

}

4.JyhBaseScriptFactory类

publicclassJyhBaseScriptFactory implementsNativeScriptFactory {
    @Override
    publicExecutableScript newScript(@NullableMap<String, Object> params) {
        returnnewJyhScript(params);
    }

    protectedclassJyhScript extendsAbstractDoubleSearchScript {
        privatedoubleprice;
        privateString category;

        //params就是搜索请求中传入的参数
        publicJyhScript(@NullableMap<String,Object> params){
            this.price = (Double)params.get("price");
            this.category = (String)params.get("category");
        }

        @Override
        publicdoublerunAsDouble() {
            //iismerchant对应着doc values中iismerchant字段的值
            longiismerchant = ((ScriptDocValues.Longs)doc().get("iismerchant")).getValue();
            doublescore = 30;
            if(iismerchant == 1) {
                score += 20;
            }
            else{
                score += this.price;
            }
            score = score < 0?0: score;
            returnscore;
        }
    }
}

5.es-plugin.properties
在src/main/resources下新增es-plugin.properties文件

plugin=com.dcharm.NativeScriptPlugin

6.打包
插件打包的方式和一般的maven项目相同，使用下面的命令

mvn clean install

打包后，插件为target/release目录下的project.zip文件

7.安装

bin/elasticsearch-plugin--urlfile:///path-to-target/project.zip --installnative-script

其中native-script为插件的名称

bin/elasticsearch-plugin--urlfile:///path-to-target/project.zip --installnative-script

安装的时候一定要注意这个路径的写法：file:///
我在这掉坑里了。




8.调用排序插件
调用自定义排序时，需要指定实现方式为native，排序名称为m2c_jyh_default

curl -XPOST localhost:9200/m2c/item/_search-d '{
  "fields": ["id","sproduct"],
  "from": 0,
  "size": 1,
  "query": {
    "function_score": {
      "query": {
        "match": {"sproduct":"nike"}
      },
      "functions": [
        {
          "script_score": {
            "lang":"native",
            "script":"m2c_jyh_default",
              "params": {
              "price": 10.0,
              "category":"12 34"
            }
          }
        }
      ],
      "boost_mode":"replace"
    }
  }
}'

上面的请求访问的是我自己测试用的索引m2c，大家在尝试的时候可以自己建立其他的索引。