Java ES分组分页实现步骤

1. 建立Elasticsearch连接

首先需要建立与Elasticsearch的连接，可以使用官方提供的Java客户端库进行操作。

// 创建连接
RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(
                new HttpHost("localhost", 9200, "http")));

2. 构建搜索请求

构建一个搜索请求，指定索引、类型、查询条件和聚合条件。

// 构建搜索请求
SearchRequest searchRequest = new SearchRequest("indexName");
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.matchAllQuery());

3. 添加聚合条件

在搜索请求中添加聚合条件，即group by条件。

// 添加聚合条件
sourceBuilder.aggregation(AggregationBuilders.terms("group_by_field").field("fieldName"));

4. 执行搜索请求

执行搜索请求，获取搜索结果。

// 执行搜索请求
searchRequest.source(sourceBuilder);
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

5. 处理搜索结果

对搜索结果进行处理，获取聚合结果，并进行分页处理。

// 处理搜索结果
Terms termsAggregation = searchResponse.getAggregations().get("group_by_field");
List<? extends Terms.Bucket> buckets = termsAggregation.getBuckets();

// 分页处理
int from = 0;
int size = 10;
List<String> result = new ArrayList<>();
for (int i = from; i < Math.min(buckets.size(), from + size); i++) {
    result.add(buckets.get(i).getKey().toString());
}

完整示例代码

// 创建连接
RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(
                new HttpHost("localhost", 9200, "http")));

// 构建搜索请求
SearchRequest searchRequest = new SearchRequest("indexName");
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.matchAllQuery());

// 添加聚合条件
sourceBuilder.aggregation(AggregationBuilders.terms("group_by_field").field("fieldName"));

// 执行搜索请求
searchRequest.source(sourceBuilder);
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

// 处理搜索结果
Terms termsAggregation = searchResponse.getAggregations().get("group_by_field");
List<? extends Terms.Bucket> buckets = termsAggregation.getBuckets();

// 分页处理
int from = 0;
int size = 10;
List<String> result = new ArrayList<>();
for (int i = from; i < Math.min(buckets.size(), from + size); i++) {
    result.add(buckets.get(i).getKey().toString());
}

// 关闭连接
client.close();

类图

classDiagram
    class RestHighLevelClient {
        +RestHighLevelClient(HttpHost[] hosts)
        +search(SearchRequest searchRequest, RequestOptions options)
        +close()
    }
    class SearchRequest {
        +SearchRequest(String index)
        +source(SearchSourceBuilder source)
    }
    class SearchSourceBuilder {
        +query(QueryBuilder query)
        +aggregation(AggregationBuilder aggregation)
    }
    class AggregationBuilder {
        +field(String fieldName)
    }
    class Terms {
        +getBuckets()
    }
    class Terms.Bucket {
        +getKey()
    }

通过以上步骤，你可以实现Java中使用Elasticsearch进行分组并分页的操作。希望对你有所帮助！