【轉】Elasticsearch Java Rest Client 指南
阿新 • • 發佈：2018-12-26
sta eve oat bubuko 增刪改查 cli for 在一起 min 
API少的可憐
原文地址：https://www.jianshu.com/p/d2c8326e8fa3
仔細看了下，5.6版本的RestHighLevelClient就這麽些API，有興趣的朋友可以去看看源碼：
以上包含了基本的增刪改查和批量操作
我翻了一下官方文檔，涼涼。確實像官方文檔說的那樣，需要完善。雖然是High Level的Client，但是東西少的可憐。
增（index）刪（delete）改（update）查（get）操作都是和Index，type，id嚴格綁定的。
不能跨Index操作
目前幾乎所有的High Level Rest Clent的中文介紹全部是照搬ES的文檔啊。我懶得抄，而且我司用的Elasticsearch 5.6
API少的可憐
明顯特性比版本6少了很多。所以，我倒是想填這個坑，但是太大了。還是拉倒吧。強烈建議直接去翻官方文檔，這個API版本不同版本的差別很大，一定去看自己使用的版本！現有的中文博客參考價值有限。包括本篇。
-
Java High Level REST Client
-
Document APIs
0x1 基本增刪改查
- 第一步創建高級Client
RestClient restClient = RestClient
.builder(new HttpHost("localhost", 9200, "http"))
.build();
RestHighLevelClient highLevelClient = new RestHighLevelClient(restClient);
- 一次演示增刪改查
//增, source 裏對象創建方式可以是JSON字符串，或者Map，或者XContentBuilder 對象
IndexRequest indexRequest = new IndexRequest("指定index", "指定type", "指定ID") .source(builder);
highLevelClient.index(indexRequest);
//刪
DeleteRequest deleteRequest = new DeleteRequest("指定index", "指定type", "指定ID");
highLevelClient.delete(deleteRequest);
//改, source 裏對象創建方式可以是JSON字符串，或者Map，或者XContentBuilder 對象
UpdateRequest updateRequest = new UpdateRequest("指定index", "指定type", "指定ID").doc(builder);
highLevelClient.update(updateRequest);
//查
GetRequest getRequest = new GetRequest("指定index", "指定type", "指定ID");
highLevelClient.get(getRequest);
- 以上四個方法都有一個***Async的方法是異步回調的，只需添加ActionListener對象即可
- Get查詢不是唯一的查詢方法，還有SearchRequest等， 但是這個GetRequest只支持單Index操作
- Get操作支持限定查詢的字段，傳入fetchSourceContext對象即可
- Update 操作演示的並不是全量替換，而是和現有文檔作合並，除了doc操作還有使用Groovy script操作。
- upsert類似update操作，不過如果文檔不存在會作為新的doc存入ES
0x2 Bulk批量操作
其實就是把一大堆IndexRequest, UpdateRequest, DeleteRequest操作放在一起。
所以缺點就是必須指定Index，否則操作沒戲。
簡單示例
BulkRequest request = new BulkRequest();
request.add(new IndexRequest("指定index", "指定type", "指定ID_1").source(XContentType.JSON,"field", "foo"));
request.add(new DeleteRequest("指定index", "指定type", "指定ID_2"));
request.add(new UpdateRequest("指定index", "指定type", "指定ID_3") .doc(XContentType.JSON,"other", "test"));
BulkResponse bulkResponse = client.bulk(request);
for (BulkItemResponse bulkItemResponse : bulkResponse) {
if (bulkItemResponse.isFailed()) {
BulkItemResponse.Failure failure = bulkItemResponse.getFailure();
continue;
}
DocWriteResponse itemResponse = bulkItemResponse.getResponse();
if (bulkItemResponse.getOpType() == DocWriteRequest.OpType.INDEX
|| bulkItemResponse.getOpType() == DocWriteRequest.OpType.CREATE) {
IndexResponse indexResponse = (IndexResponse) itemResponse;
} else if (bulkItemResponse.getOpType() == DocWriteRequest.OpType.UPDATE) {
UpdateResponse updateResponse = (UpdateResponse) itemResponse;
} else if (bulkItemResponse.getOpType() == DocWriteRequest.OpType.DELETE) {
DeleteResponse deleteResponse = (DeleteResponse) itemResponse;
}
}
0x3 SearchRequest高級查詢
支持多文檔查詢、聚合操作。可以完全取代GetRequest。
// 創建
SearchRequest searchRequest = new SearchRequest();
SearchSourceBuilder builder = new SearchSourceBuilder();
searchSourceBuilder.query(xxxQuery);
searchRequest.source(builder);
可以在創建的時候指定index，SearchRequest searchRequest = new SearchRequest("some_index*");,支持帶*號的模糊匹配
當然，這並不是最厲害的地方，最NB的地方是，支持QueryBuilder，兼容之前TransportClient的代碼
- 我自己寫的跨Index模糊查詢
SearchRequest searchRequest = new SearchRequest("gdp_tops*");
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.termQuery("city", "北京市"));
sourceBuilder.timeout(new TimeValue(60, TimeUnit.SECONDS));
searchRequest.source(sourceBuilder);
try {
SearchResponse response = highLevelClient.search(searchRequest);
Arrays.stream(response.getHits().getHits())
.forEach(i -> {
System.out.println(i.getIndex());
System.out.println(i.getSource());
System.out.println(i.getType());
});
System.out.println(response.getHits().totalHits);
} catch (IOException e) {
e.printStackTrace();
}
- 官方給出的聚合查詢
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
TermsAggregationBuilder aggregation = AggregationBuilders.terms("by_company")
.field("company.keyword");
aggregation.subAggregation(AggregationBuilders.avg("average_age")
.field("age"));
searchSourceBuilder.aggregation(aggregation);
- 當然還支持異步查詢
官方示例
client.searchAsync(searchRequest, new ActionListener<SearchResponse>() {
@Override
public void onResponse(SearchResponse searchResponse) {
}
@Override
public void onFailure(Exception e) {
}
});
- 查詢結果處理
查詢結束後會得到一個SearchResponse對象，可以拿到查詢狀態，消耗時間，查詢到的總條目數等參數，具體結果操作
SearchHit[] searchHits = hits.getHits();
for (SearchHit hit : searchHits) {
// 結果的Index
String index = hit.getIndex();
// 結果的type
String type = hit.getType();
// 結果的ID
String id = hit.getId();
// 結果的評分
float score = hit.getScore();
// 查詢的結果 JSON字符串形式
String sourceAsString = hit.getSourceAsString();
// 查詢的結果 Map的形式
Map<String, Object> sourceAsMap = hit.getSourceAsMap();
// Document的title
String documentTitle = (String) sourceAsMap.get("title");
// 結果中的某個List
List<Object> users = (List<Object>) sourceAsMap.get("user");
// 結果中的某個Map
Map<String, Object> innerObject = (Map<String, Object>) sourceAsMap.get("innerObject");
}
- 聚合查詢
前面演示的是正常查詢，聚合查詢官方文檔也有展示
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
TermsAggregationBuilder aggregation = AggregationBuilders.terms("by_company")
.field("company.keyword");
aggregation.subAggregation(AggregationBuilders.avg("average_age")
.field("age"));
searchSourceBuilder.aggregation(aggregation);
和query查詢一樣，searchSourceBuilder使用aggregation()方法即可
查詢到的結果處理也跟普通查詢類似，處理一下Bucket就可以展示到接口了
Aggregations aggregations = searchResponse.getAggregations();
Terms byCompanyAggregation = aggregations.get("by_company");
Bucket elasticBucket = byCompanyAggregation.getBucketByKey("Elastic");
Avg averageAge = elasticBucket.getAggregations().get("average_age");
double avg = averageAge.getValue();
0x4 分頁和滾動搜索
有時候結果需要分頁查詢，推薦使用searchSourceBuilder的
sourceBuilder.from(0);
sourceBuilder.size(5);
有時候需要查詢的數據太多，可以考慮使用SearchRequest.scroll()方法拿到scrollId;之後再使用SearchScrollRequest
其用法如下：
SearchRequest searchRequest = new SearchRequest("posts");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(matchQuery("title", "Elasticsearch"));
searchSourceBuilder.size(size);
searchRequest.source(searchSourceBuilder);
searchRequest.scroll(TimeValue.timeValueMinutes(1L));
SearchResponse searchResponse = client.search(searchRequest);
String scrollId = searchResponse.getScrollId();
SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId);
scrollRequest.scroll(TimeValue.timeValueSeconds(30));
SearchResponse searchScrollResponse = client.searchScroll(scrollRequest);
scrollId = searchScrollResponse.getScrollId();
hits = searchScrollResponse.getHits();
assertEquals(3, hits.getTotalHits());
assertEquals(1, hits.getHits().length);
assertNotNull(scrollId);
Scroll查詢的使用場景是密集且前後有關聯的查詢。如果只是一般的分頁，可以使用size from來處理
【轉】Elasticsearch Java Rest Client 指南