elasticsearch 自定义similarity 插件开发

 

原文  http://www.cnblogs.com/luanfei/p/4029442.html

主题 Elastic Search

转自: http://www.chepoo.com/elasticsearch-similarity-custom-plug-in-development.html

在搜索开发中，我们要修改打分机制，就需要自定义similarity。现在来简单说一下elasticsearch下的自定义similarity 插件开发。

网上的 https://github.com/tlrx/elasticsearch-custom-similarity-provider 仅仅支持0.20.0.Beta1-SNAPSHOT版本，现在我们用的版本是elasticsearch 0.90版本以上。那个例子现在不能用，我修改了一下。

1.继承DefaultSimilarity，实现自己的搜索打分机制。

package org.elasticsearch.index.similarity;
 
import org.apache.lucene.search.similarities.DefaultSimilarity;
 
/**
 * Custom similarity class
 * 
 * @author xq
 *
 */
public class CustomSimilarity extends DefaultSimilarity {
 
  @Override
  public float idf(long docFreq, long numDocs) {
    return 1.0f;
  }
 
}

2.继续AbstractSimilarityProvider，把自定义的打分机制类加载到elasticsearch中。

package org.elasticsearch.index.similarity;
 
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.inject.assistedinject.Assisted;
import org.elasticsearch.common.settings.Settings;
 
/**
 * Simple {@link SimilarityProvider} for a {@link CustomSimilarity}
 * 
 * @author xq
 *
 */
public class CustomSimilarityProvider extends AbstractSimilarityProvider {
 
  private CustomSimilarity similarity;
 
  @Inject
  public CustomSimilarityProvider(@Assisted String name, @Assisted Settings settings) {
    super(name);
    this.similarity = new CustomSimilarity();
  }
 
 
 
  public CustomSimilarity get() {
    return similarity;
  }
}

3.继承AbstractPlugin作为elasticsearch插件使用

public class CustomerSimilarityPlugin extends AbstractPlugin {
 
  @Override public String name() {
    return "customer-similarity";
  }
 
 
  @Override public String description() {
    return "customer similarity";
  }
 
 
  @Override public void processModule(Module module) {
    if (module instanceof SimilarityModule) {
      SimilarityModule similarityModule = (SimilarityModule) module;
      similarityModule.addSimilarity("customer-similarity", CustomSimilarityProvider.class);
    }
  }
}

4.使用

curl -XPOST 'http://host:port/tweeter/' -d '
{
  "settings": {
    "similarity": {
      "index": {
        "type": "org.elasticsearch.index.similarity.CustomSimilarityProvider"
      },
      "search": {
        "type": "org.elasticsearch.index.similarity.CustomSimilarityProvider"
      }
    }
  }
}'

在创建mapping的使用自定义的打分规则：

{
  "news" : {
    "properties" : {
      "title" : { "type" : "string", "similarity" : "my_similarity" }
    }
}

在elasticsearch.yml中配置自定义的打分规则类为默认规则。 index.similarity.default.type: my_similarity