ElasticSearch Java API只需十招，轻松掌握变专家！

环境：springboot2.4.12 + elasticsearch7.8.0

      Elasticsearch是一种开源的、分布式的、实时的搜索和分析引擎。它允许你存储，搜索和分析大量数据，通常用于为网站或应用程序提供强大的搜索功能。

      Java API是Elasticsearch提供的官方客户端，它允许Java开发者轻松地与Elasticsearch服务器进行交互。下面是一些关于如何使用Java API来调用Elasticsearch的常用方法。

注意：这里为了方便使用springboot项目（避免还要单独引用其它包）

相关依赖

 
  org.springframework.boot
  spring-boot-starter-web
 
 
  org.elasticsearch
  elasticsearch
  7.8.0
 
 
  org.elasticsearch.client
  elasticsearch-rest-high-level-client
  7.8.0

索引操作

高级别的Rest客户端对象

private static RestHighLevelClient client = 
  new RestHighLevelClient(RestClient.builder(
    new HttpHost("localhost", 9200, "http"))) ;

1. 创建索引

public static void createIndex(String index) throws Exception {
  CreateIndexRequest request = new CreateIndexRequest(index) ;
  CreateIndexResponse response = client.indices().create(request, RequestOptions.DEFAULT) ;
  boolean ack = response.isAcknowledged() ;
  System.out.println("ack = " + ack) ;
}

2. 查看索引

public static void viewIndex(String index) throws Exception {
  GetIndexRequest request = new GetIndexRequest(index) ;
  GetIndexResponse response = client.indices().get(request, RequestOptions.DEFAULT) ;
  System.out.println("aliases: " + response.getAliases() + "\n"
    + "mappings: " + response.getMappings() + "\n"
    + "settings: " + response.getSettings()) ;
}

3. 删除索引

public static void deleteIndex(String index) throws Exception {
  DeleteIndexRequest request = new DeleteIndexRequest(index) ;
  AcknowledgedResponse response = client.indices().delete(request, RequestOptions.DEFAULT) ;
  System.out.println("ack: " + response.isAcknowledged()) ;
}

文档操作

private static RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(new HttpHost("localhost", 9200, "http"))) ;

1. 创建文档

public static void createDoc(String index, Users users) throws Exception {
  IndexRequest request = new IndexRequest() ;
  // 设置索引及唯一标识
  request.index(index).id("1001") ;
  ObjectMapper objectMapper = new ObjectMapper() ;
  String jsonString = objectMapper.writeValueAsString(users) ;
  // 添加文档数据及数据格式
  request.source(jsonString, XContentType.JSON) ;
  IndexResponse response = client.index(request, RequestOptions.DEFAULT) ;
  System.out.println("_index: " + response.getIndex() + "\n"
      + "_id: " + response.getId() + "\n"
      + "_result: " + response.getResult()) ;
}

2. 更新文档

public static void updateDoc(String index, String id) throws Exception {
  UpdateRequest request = new UpdateRequest() ;
  // 配置修改参数
  request.index(index).id(id) ;
  Map source = new HashMap() ;
  source.put("sex", "女") ;
  request.doc(source, XContentType.JSON) ;
  UpdateResponse response = client.update(request, RequestOptions.DEFAULT) ;
  System.out.println("_index: " + response.getIndex() + "\n"
      + "_id: " + response.getId() + "\n"
      + "_result: " + response.getResult()) ;
}

3. 查询文档

public static void viewDoc(String index, String id) throws Exception {
  GetRequest request = new GetRequest().index(index).id(id) ;
  GetResponse response = client.get(request, RequestOptions.DEFAULT) ;
  System.out.println("_index: " + response.getIndex() + "\n"
      + "_type: " + response.getType() + "\n"
      + "_id: " + response.getId() + "\n"
      + "source: " + response.getSourceAsString()) ;
}

4. 删除文档

public static void deleteIndex(String index, String id) throws Exception {
  DeleteRequest request = new DeleteRequest().index(index).id(id) ;
  DeleteResponse response = client.delete(request, RequestOptions.DEFAULT) ;
  System.out.println(response.toString()) ;
}

5. 批量操作

public static void batchOperator(String index) throws Exception {
  BulkRequest request = new BulkRequest() ;
  request.add(new IndexRequest().index(index).id("1002").source(XContentType.JSON, "name","老六", "sex", "男", "age", 20)) ;
  request.add(new IndexRequest().index(index).id("1003").source(XContentType.JSON, "name","外网", "sex", "女", "age", 10)) ;
  request.add(new IndexRequest().index(index).id("1004").source(XContentType.JSON, "name","莉莉", "sex", "女", "age", 35)) ;
  BulkResponse response = client.bulk(request, RequestOptions.DEFAULT) ;
  System.out.println("took: " + response.getTook() + "\n"
      + "items: " + new ObjectMapper().writeValueAsString(response.getItems())) ;
}

6. 高级查询

public static void highSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.matchAllQuery()) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
}

7. term精确查询

public static void highTermSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.termQuery("age", "20")) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
}

8. 分页查询

public static void highPagingSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.matchAllQuery()) ;
  builder.from(1) ;
  builder.size(2) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
}

9. 分页&排序查询

public static void highPagingAndSortSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.matchAllQuery()) ;
  builder.from(0) ;
  builder.size(20) ;
  builder.sort("age", SortOrder.ASC) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
}

10. 分页&排序&过滤字段查询

public static void highPagingAndSortAndFilterFieldSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.matchAllQuery()) ;
  builder.from(0) ;
  builder.size(20) ;
  builder.sort("age", SortOrder.ASC) ;
  String[] includes = {"name"} ;
  String[] excludes = {} ;
  builder.fetchSource(includes, excludes) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
}

11. 范围查询

public static void highBoolSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.matchAllQuery()) ;
  builder.from(0) ;
  builder.size(20) ;
  builder.sort("age", SortOrder.ASC) ;
  RangeQueryBuilder rangeBuilder = QueryBuilders.rangeQuery("age");
  rangeBuilder.gte(15) ;
  rangeBuilder.lte(30) ;
  builder.query(rangeBuilder) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
}

12. 高亮查询

public static void highHighLightSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.query(QueryBuilders.matchQuery("name", "莉莉")) ;
  HighlightBuilder highLightBuilder = new HighlightBuilder() ;
  highLightBuilder.preTags("") ;
  highLightBuilder.postTags("") ;
  highLightBuilder.field("name") ;
  builder.highlighter(highLightBuilder) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString() + "\n"
        + "highlight: " + hit.getHighlightFields()) ;
  }
}

13. 聚合查询

public static void highAggsSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.aggregation(AggregationBuilders.avg("avg_age").field("age")) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString())  ;
  }
  System.out.println(((ParsedAvg)response.getAggregations().iterator().next()).getValue()) ;
}

14. 分组统计

public static void highGroupSearch(String index) throws Exception {
  SearchRequest request = new SearchRequest().indices(index) ;
  SearchSourceBuilder builder = new SearchSourceBuilder() ;
  builder.aggregation(AggregationBuilders.terms("age_groupby").field("age")) ;
  request.source(builder) ;
  SearchResponse response = client.search(request, RequestOptions.DEFAULT) ;
  SearchHits hits = response.getHits() ;
  System.out.println("took: " + response.getTook() + "\n"
      + "timeout: " + response.isTimedOut() + "\n"
      + "total: " + hits.getTotalHits() + "\n"
      + "MaxScore: " + hits.getMaxScore()) ;
  for (SearchHit hit : hits) {
    System.out.println(hit.getSourceAsString()) ;
  }
  System.out.println(response) ;
}

完毕！！！