ElasticSearch的JavaAPI简单使用
ES是一个**开源的高扩展的分布式全文搜索引擎，**是整个Elastic Stack技术栈的核心。它可以近乎实时的存储、检索数据；本身扩展性很好，可以扩展到上百台服务器，处理PB级别的数据。Elasticsearch软件是由Java语言开发的，所以也可以通过Java API的方式对Elasticsearch服务进行访问，并且操作的方式基本和Http操作一致
本文已经收录到我的Github: https://github.com/chenliang15405/common-study/tree/main/elasticsearch-demo
Maven依赖
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pom.xml中加入ES需要的依赖<dependencies> <dependency> <groupId>org.elasticsearchgroupId> <artifactId>elasticsearchartifactId> <version>7.8.0version> dependency> <dependency> <groupId>org.elasticsearch.clientgroupId> <artifactId>elasticsearch-rest-high-level-clientartifactId> <version>7.8.0version> dependency> <dependency> <groupId>org.apache.logging.log4jgroupId> <artifactId>log4j-apiartifactId> <version>2.8.2version> dependency> <dependency> <groupId>org.apache.logging.log4jgroupId> <artifactId>log4j-coreartifactId> <version>2.8.2version> dependency> <dependency> <groupId>com.fasterxml.jackson.coregroupId> <artifactId>jackson-databindartifactId> <version>2.9.9version> dependency> <dependency> <groupId>junitgroupId> <artifactId>junitartifactId> <version>4.12version> dependency> dependencies> -
如果在运行时报错
java.lang.NoSuchMethodError: org.elasticsearch.client.Request.addParameters那么应该是发生了依赖冲突，新建一个Maven项目，最好不要直接创建springboot项目，可能会有依赖冲突，将上面的依赖加入到maven项目的pom中
链接ES客户端
因为使用的highLevel的ES客户端，所以可以很方便的连接到ES，只需要通过host和port就可以直接连接
public static void main(String[] args) throws IOException {
RestHighLevelClient esClient = new RestHighLevelClient(
RestClient.builder(new HttpHost("localhost", 9200, "http"))
);
esClient.close();
}
如果代码执行正常，没有报错那么就表示正常连接到了ES节点，可以通过获取到的RestHighLevelClient对象进行操作
索引操作
加入了maven依赖，那么就可以通过Java客户端链接到ES进行操作，首先进行索引的基本操作
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创建索引
RestHighLevelClient esClient = new RestHighLevelClient( RestClient.builder(new HttpHost("localhost", 9200, "http")) ); @Test public void index_create() throws IOException { // 创建索引 - 请求对象 CreateIndexRequest request = new CreateIndexRequest("test"); // 发送请求，获取响应 CreateIndexResponse response = esClient.indices().create(request, RequestOptions.DEFAULT); boolean acknowledged = response.isAcknowledged(); // 响应状态 System.out.println("操作状态 = " + acknowledged); } -
查询索引
RestHighLevelClient esClient = new RestHighLevelClient( RestClient.builder(new HttpHost("localhost", 9200, "http")) ); @Test public void index_get() throws IOException { GetIndexRequest request = new GetIndexRequest("test"); GetIndexResponse response = esClient.indices().get(request, RequestOptions.DEFAULT); System.out.println(Arrays.toString(response.getIndices())); System.out.println(response.getMappings()); System.out.println(response.getSettings()); } -
删除索引
RestHighLevelClient esClient = new RestHighLevelClient( RestClient.builder(new HttpHost("localhost", 9200, "http")) ); @Test public void index_delete() throws IOException { DeleteIndexRequest request = new DeleteIndexRequest("test"); AcknowledgedResponse response = esClient.indices().delete(request, RequestOptions.DEFAULT); System.out.println(response.isAcknowledged()); }
文档操作
文档作为数据的对象，可以通过ES的客户端对象直接操作
RestHighLevelClient对象和上面的创建方式相同，此处省略
文档基本操作
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创建文档
@Test public void doc_create() throws IOException { IndexRequest request = new IndexRequest(); // 设置操作的索引和当前插入的文档的id request.index("people").id("1001"); User user = new User(); user.setName("张三"); user.setAge(10); user.setSex("男"); ObjectMapper mapper = new ObjectMapper(); String userJson = mapper.writeValueAsString(user); request.source(userJson, XContentType.JSON); IndexResponse response = esClient.index(request, RequestOptions.DEFAULT); System.out.println(response); System.out.println("_index" + response.getIndex()); System.out.println("_id" + response.getId()); System.out.println("_result" + response.getResult()); } -
更新文档
@Test public void doc_update() throws IOException { UpdateRequest request = new UpdateRequest(); request.index("people").id("1001"); request.doc(XContentType.JSON, "sex", "女"); UpdateResponse response = esClient.update(request, RequestOptions.DEFAULT); System.out.println(response); } -
查询文档
@Test public void doc_get() throws IOException { GetRequest request = new GetRequest(); request.index("people").id("1001"); GetResponse response = esClient.get(request, RequestOptions.DEFAULT); System.out.println(response); System.out.println(response.getSource()); } -
删除文档
@Test public void doc_delete() throws IOException { DeleteRequest request = new DeleteRequest(); request.index("people").id("1001"); DeleteResponse response = esClient.delete(request, RequestOptions.DEFAULT); System.out.println(response); }
文档批量操作
一般操作ES的数据都是批量保存或者批量删除，如果通过一条一条的操作，那么效率非常的低，可以通过批量操作API提高效率
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批量保存
@Test public void doc_insert_batch() throws IOException { BulkRequest request = new BulkRequest(); request.add(new IndexRequest().index("people").id("1001").source(XContentType.JSON, "name", "张三", "sex", "男", "age", 10)); request.add(new IndexRequest().index("people").id("1002").source(XContentType.JSON, "name", "李四", "sex", "男", "age", 11)); request.add(new IndexRequest().index("people").id("1003").source(XContentType.JSON, "name", "王五", "sex", "男", "age", 12)); request.add(new IndexRequest().index("people").id("1004").source(XContentType.JSON, "name", "王五1", "sex", "男", "age", 8)); request.add(new IndexRequest().index("people").id("1005").source(XContentType.JSON, "name", "王五2", "sex", "男", "age", 9)); request.add(new IndexRequest().index("people").id("1006").source(XContentType.JSON, "name", "王五33", "sex", "男", "age", 7)); BulkResponse response = esClient.bulk(request, RequestOptions.DEFAULT); System.out.println(response.getTook()); System.out.println(Arrays.toString(response.getItems())); } -
批量删除
@Test public void doc_delete_batch() throws IOException { BulkRequest request = new BulkRequest(); request.add(new DeleteRequest().index("people").id("1001")); request.add(new DeleteRequest().index("people").id("1002")); request.add(new DeleteRequest().index("people").id("1003")); BulkResponse response = esClient.bulk(request, RequestOptions.DEFAULT); System.out.println(response.getTook()); System.out.println(response); }
文档高级查询
高级查询、分组查询、分页、排序、聚合操作等，作为ES常用的查询操作，ES的Java客户端也提供了好用的API进行操作
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查询指定索引的所有数据
@Test public void match_all() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); builder.query(QueryBuilders.matchAllQuery()); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
term查询
@Test public void query_term() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); builder.query(QueryBuilders.termQuery("age", 10)); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
分页查询
@Test public void query_page() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); builder.query(QueryBuilders.matchAllQuery()); // from指定的是页数开始的偏移量， （当前页数 - 1）* size builder.from(0); builder.size(3); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
排序查询
@Test public void query_sort() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); builder.query(QueryBuilders.matchAllQuery()); builder.sort("age", SortOrder.DESC); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
查询并过滤字段
@Test public void query_filter() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); builder.query(QueryBuilders.matchAllQuery()); String[] excludes = { }; String[] includes = { "name"}; // 过滤字段，指定只包含某些字段，或者需要排除某些字段 builder.fetchSource(includes, excludes); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
bool条件查询，多条件Must
@Test public void query_bool_must() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery(); // 多条件查询，must -> 一定需要匹配到 boolQueryBuilder.must(QueryBuilders.matchQuery("age", 10)); boolQueryBuilder.must(QueryBuilders.matchQuery("sex", "女")); builder.query(boolQueryBuilder); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
bool条件查询，多条件should
@Test public void query_bool_should() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery(); // 多条件查询，should -> 如果当前这条数据满足两个should条件中的任意一个，则表示满足条件 boolQueryBuilder.should(QueryBuilders.matchQuery("age", 10)); boolQueryBuilder.should(QueryBuilders.matchQuery("sex", "女")); builder.query(boolQueryBuilder); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
范围查询
@Test public void query_range() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); // 根据某个字段构建范围查询 RangeQueryBuilder rangeQueryBuilder = QueryBuilders.rangeQuery("age"); // 指定范围查询的条件数据 rangeQueryBuilder.gte(9); rangeQueryBuilder.lte(12); builder.query(rangeQueryBuilder); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
模糊查询
@Test public void query_fuzzy() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); // 模糊查询，指定字段名称进行模糊查询，后面的指定模糊匹配的字符个数 builder.query(QueryBuilders.fuzzyQuery("name", "王五").fuzziness(Fuzziness.ONE)); request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); SearchHits hits = response.getHits(); System.out.println("took:" + response.getTook()); System.out.println("timeout:" + response.isTimedOut()); System.out.println("total:" + hits.getTotalHits()); System.out.println("MaxScore:" + hits.getMaxScore()); System.out.println("hits========>>"); for (SearchHit hit : hits) { //输出每条查询的结果信息 System.out.println(hit.getSourceAsString()); } System.out.println("<<========"); } -
高亮查询
@Test public void query_highlight() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); TermsQueryBuilder termsQueryBuilder = QueryBuilders.termsQuery("sex", "女"); // 设置查询方式 builder.query(termsQueryBuilder); // 构建高亮字段 HighlightBuilder highlightBuilder = new HighlightBuilder(); highlightBuilder.preTags(""); // 设置标签前缀 highlightBuilder.postTags(""); // 设置标签后缀 highlightBuilder.field("sex"); // 设置高亮字段 // 设置高亮查询 builder.highlighter(highlightBuilder); // 设置请求体 request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); System.out.println(response); SearchHits hits = response.getHits(); System.out.println("took::"+response.getTook()); System.out.println("time_out::"+response.isTimedOut()); System.out.println("total::"+hits.getTotalHits()); System.out.println("max_score::"+hits.getMaxScore()); System.out.println("hits::::>>"); for (SearchHit hit : hits) { String sourceAsString = hit.getSourceAsString(); System.out.println(sourceAsString); //打印高亮结果 Map<String, HighlightField> highlightFields = hit.getHighlightFields(); System.out.println(highlightFields); } } -
聚合查询—最大值
@Test public void query_aggs_max() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); // 聚合查询，获取最大的age字段的数 builder.aggregation(AggregationBuilders.max("maxAge").field("age")); // 设置请求体 request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); System.out.println(response); } -
聚合查询—分组查询
@Test public void query_aggs_group() throws IOException { SearchRequest request = new SearchRequest(); request.indices("people"); SearchSourceBuilder builder = new SearchSourceBuilder(); // 聚合查询，获取最大的age字段的数 builder.aggregation(AggregationBuilders.terms("age_groupby").field("age")); // 设置请求体 request.source(builder); SearchResponse response = esClient.search(request, RequestOptions.DEFAULT); System.out.printl n(response); }
文档的高级查询，JavaAPI的操作方式和语法基本和Http操作的一致，只不过将对应的Http方式替换为了API，可以更好的在程序中进行ES操作，下一篇一起看看如何在SpringBoot和ElasticSearch进行集成吧，更加方便的操作ES与索引数据
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