elasticsearchTemplate.search 聚合统计

ElasticsearchTemplate.search()方法可以用于执行各种类型的搜索操作，包括聚合统计。聚合统计是一种高级搜索技术，用于对搜索结果进行分组、计数和统计等操作。

下面是一个示例代码，演示如何使用ElasticsearchTemplate.search()方法进行聚合统计：

import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.bucket.histogram.DateHistogramInterval;
import org.elasticsearch.search.aggregations.bucket.histogram.Histogram;
import org.elasticsearch.search.aggregations.metrics.avg.Avg;
import org.elasticsearch.search.aggregations.metrics.sum.Sum;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.elasticsearch.core.ElasticsearchTemplate;
import org.springframework.stereotype.Component;

import java.util.Date;

@Component
public class MyAggregation {

    @Autowired
    private ElasticsearchTemplate elasticsearchTemplate;

    public void aggregation() {
        Histogram dateHistogram = AggregationBuilders.dateHistogram("date_histogram")
                .field("timestamp")
                .dateHistogramInterval(DateHistogramInterval.HOUR)
                .subAggregation(AggregationBuilders.avg("average").field("value"))
                .subAggregation(AggregationBuilders.sum("sum").field("value"))
                .subAggregation(AggregationBuilders.count("count").field("value"))
                .subAggregation(AggregationBuilders.max("max").field("value"))
                .subAggregation(AggregationBuilders.min("min").field("value"));

        SearchQuery searchQuery = new NativeSearchQueryBuilder()
                .withQuery(QueryBuilders.matchAllQuery())
                .withSearchType(SearchType.QUERY_THEN_FETCH)
                .withIndices("my_index")
                .withTypes("my_type")
                .addAggregation(dateHistogram)
                .build();

        Aggregations aggregations = elasticsearchTemplate.query(searchQuery, new ResultsExtractor<Aggregations>() {
            @Override
            public Aggregations extract(SearchResponse response) {
                return response.getAggregations();
            }
        });

        Histogram histogram = aggregations.get("date_histogram");
        for (Histogram.Bucket entry : histogram.getBuckets()) {
            Date key = (Date) entry.getKey();
            long docCount = entry.getDocCount();
            Avg avg = entry.getAggregations().get("average");
            Sum sum = entry.getAggregations().get("sum");
            long count = entry.getAggregations().get("count").getValue();
            double max = entry.getAggregations().get("max").getValue();
            double min = entry.getAggregations().get("min").getValue();
            System.out.println("Key: " + key + ", Doc count: " + docCount + ", Average: " + avg.getValue() + ", Sum: " + sum.getValue() + ", Count: " + count + ", Max: " + max + ", Min: " + min);
        }
    }

}

在上面的示例代码中，我们定义了一个名为date_histogram的直方图聚合，它将搜索结果按照时间戳字段进行分组，并且为每个分组计算了平均值、总和、计数、最大值和最小值。我们将该聚合添加到搜索查询中，并使用ElasticsearchTemplate.query()方法执行查询。最后，我们迭代直方图聚合的每个分组，并打印出每个分组的统计信息。

这只是一个简单的聚合统计示例，Elasticsearch支持更多类型的聚合，包括桶聚合、指标聚合、嵌套聚合等。你可以根据自己的需求选择适合的聚合类型，实现更加复杂和有用的聚合统计功能。