根据sql,es的查询条件，怎么用java es api写出来。

使用Java的Elasticsearch（ES）API来编写查询条件，通常涉及构建查询体、执行查询和处理结果三个主要步骤。下面将详细介绍如何根据SQL查询条件来使用Java的ES API进行编写。

1. 构建查询体

1.1 SQL条件与ES查询体对应关系：

• SELECT语句：

  • SQL: SELECT field1, field2 FROM index WHERE condition
  • ES API：

    java
    复制代码
    SearchRequest searchRequest = new SearchRequest("index");
    SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
    sourceBuilder.fetchSource(new String[]{"field1", "field2"}, null); // 指定返回字段
    

• WHERE条件：

  • SQL: WHERE field = value
  • ES API：

    java
    复制代码
    sourceBuilder.query(QueryBuilders.termQuery("field", "value"));
    

• 复杂条件（AND、OR等）：

  • SQL: WHERE field1 = value1 AND field2 = value2
  • ES API：

    java
    复制代码
    BoolQueryBuilder boolQuery = QueryBuilders.boolQuery()
        .must(QueryBuilders.termQuery("field1", "value1"))
        .must(QueryBuilders.termQuery("field2", "value2"));
    sourceBuilder.query(boolQuery);
    

1.2 聚合查询与分页：

• 聚合查询：

  • SQL: SELECT COUNT(*) FROM index WHERE condition GROUP BY field
  • ES API：

    java
    复制代码
    TermsAggregationBuilder aggregation = AggregationBuilders.terms("by_field").field("field");
    sourceBuilder.aggregation(aggregation);
    

• 分页：

  • SQL: LIMIT 10 OFFSET 0
  • ES API：

    java
    复制代码
    sourceBuilder.from(0); // 起始位置
    sourceBuilder.size(10); // 返回数量
    

2. 执行查询

2.1 创建Elasticsearch客户端：

java
复制代码
RestHighLevelClient client = new RestHighLevelClient(
    RestClient.builder(new HttpHost("localhost", 9200, "http")));

2.2 执行搜索请求：

java
复制代码
SearchRequest searchRequest = new SearchRequest("index");
searchRequest.source(sourceBuilder);

try {
    SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
    // 处理搜索结果
} catch (IOException e) {
    e.printStackTrace();
} finally {
    try {
        client.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

3. 处理查询结果

3.1 解析查询结果：

java
复制代码
SearchHits hits = searchResponse.getHits();
for (SearchHit hit : hits.getHits()) {
    Map<String, Object> sourceAsMap = hit.getSourceAsMap();
    // 处理每个文档的数据
}

3.2 处理聚合结果：

java
复制代码
Terms byFieldAggregation = searchResponse.getAggregations().get("by_field");
List<? extends Terms.Bucket> buckets = byFieldAggregation.getBuckets();
for (Terms.Bucket bucket : buckets) {
    String keyAsString = bucket.getKeyAsString();
    long docCount = bucket.getDocCount();
    // 处理每个聚合桶的数据
}

完整示例代码：

java
复制代码
import org.apache.http.HttpHost;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.builder.SearchSourceBuilder;

import java.io.IOException;
import java.util.Map;

public class ElasticsearchExample {

    public static void main(String[] args) {
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")));

        SearchRequest searchRequest = new SearchRequest("index");
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.query(QueryBuilders.termQuery("field", "value"));

        searchRequest.source(sourceBuilder);

        try {
            // 执行搜索请求
            SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
            
            // 处理搜索结果
            SearchHits hits = searchResponse.getHits();
            for (SearchHit hit : hits.getHits()) {
                Map<String, Object> sourceAsMap = hit.getSourceAsMap();
                System.out.println(sourceAsMap);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                client.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

通过上述步骤，可以利用Java的Elasticsearch API根据SQL查询条件构建相应的ES查询体，并执行查询操作，最后处理和解析查询结果，从而实现对Elasticsearch索引数据的灵活检索和聚合分析。