Es之java各种查询操作

在Elasticsearch中，使用Java进行各种查询操作通常涉及到Elasticsearch客户端库，如Java High Level REST Client。以下是一些常见查询操作的示例代码：

1. 查询所有文档：

RestHighLevelClient client = new RestHighLevelClient(...);
SearchRequest searchRequest = new SearchRequest("index_name");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchAllQuery());
searchRequest.source(searchSourceBuilder);
 
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits searchHits = searchResponse.getHits();
for (SearchHit hit : searchHits) {
    System.out.println(hit.getSourceAsString());
}
 
client.close();

2. 根据条件查询文档：

RestHighLevelClient client = new RestHighLevelClient(...);
SearchRequest searchRequest = new SearchRequest("index_name");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchQuery("field_name", "value"));
searchRequest.source(searchSourceBuilder);
 
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits searchHits = searchResponse.getHits();
for (SearchHit hit : searchHits) {
    System.out.println(hit.getSourceAsString());
}
 
client.close();

3. 分页查询：

SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.from(0); // 起始位置
searchSourceBuilder.size(10); // 每页数量
searchSourceBuilder.query(QueryBuilders.matchAllQuery());
 
SearchRequest searchRequest = new SearchRequest("index_name");
searchRequest.source(searchSourceBuilder);
 
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits searchHits = searchResponse.getHits();
for (SearchHit hit : searchHits) {
    System.out.println(hit.getSourceAsString());
}

4. 排序查询：

SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchAllQuery());
searchSourceBuilder.sort("field_name", SortOrder.ASC); // 根据field_name字段升序排序
 
SearchRequest searchRequest = new SearchRequest("index_name");
searchRequest.source(searchSourceBuilder);
 
SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits searchHits = searchResponse.getHits();
for (SearchHit hit : se