分布式搜索引擎-ElasticSearch（下集）

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分布式搜索引擎-elasticsearch（下集）

注意：ElasticSearch版本为7.6.1

什么是ElasticSearch

ElasticSearch是一个基于Lucene的搜索服务器。它提供了一个分布式多用户能力的全文搜索引擎，基于RESTful web接口。Elasticsearch是用Java开发的，并作为Apache许可条款下的开放源码发布，是当前流行的企业级搜索引擎。设计用于云计算中，能够达到实时搜索，稳定，可靠，快速，安装使用方便。

我们建立一个网站或应用程序，并要添加搜索功能，但是想要完成搜索工作的创建是非常困难的。我们希望搜索解决方案要运行速度快，我们希望能有一个零配置和一个完全免费的搜索模式，我们希望能够简单地使用JSON通过HTTP来索引数据，我们希望我们的搜索服务器始终可用，我们希望能够从一台开始并扩展到数百台，我们要实时搜索，我们要简单的多租户，我们希望建立一个云的解决方案。因此我们利用Elasticsearch来解决所有这些问题及可能出现的更多其它问题。摘选自《百度百科》

GET goods/_search { "query": { "match_all": {} } , "sort": [ { "od": { "order": "desc" } } ] , "from" : 0 , "size": 2 }

{ "took" : 1, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 4, "relation" : "eq" }, "max_score" : null, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "4", "_score" : null, "_source" : { "title" : "IQOONEO5", "content" : "IQOONEO5 高通骁龙870Soc ,", "price" : "2499", "od" : 4 }, "sort" : [ 4 ] }, { "_index" : "goods", "_type" : "_doc", "_id" : "3", "_score" : null, "_source" : { "title" : "小米11", "content" : "小米11 高通骁龙888Soc ,1亿像素", "price" : "4500", "od" : 3 }, "sort" : [ 3 ] } ] } }

可以选择一个或者多个字段高亮，然后被选择的这些字段如果被条件匹配到则会默认加em标签

GET goods/_search { "query": { "match": { "title": "华为P40" } }, "highlight": { "fields": { "title": {} } } }

结果

{ "took" : 6, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 2.7309713, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "1", "_score" : 2.7309713, "_source" : { "title" : "华为P40", "content" : "华为P40 8+256G，麒麟990Soc，贼牛逼", "price" : "4999", "od" : 1 }, "highlight" : { "title" : [ "华为P40" ] } }, { "_index" : "goods", "_type" : "_doc", "_id" : "2", "_score" : 1.5241971, "_source" : { "title" : "华为Mate30", "content" : "华为Mate30 8+128G，麒麟990Soc", "price" : "3998", "od" : 2 }, "highlight" : { "title" : [ "华为Mate30" ] } } ] } }

默认是em标签，我们可以更改他的前缀和后缀，利用前端的知识

GET goods/_search { "query": { "match": { "title": "华为P40" } }, "highlight": { "pre_tags": "", "post_tags": "" , "fields": { "title": {} } } }

{ "took" : 3, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 2.7309713, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "1", "_score" : 2.7309713, "_source" : { "title" : "华为P40", "content" : "华为P40 8+256G，麒麟990Soc，贼牛逼", "price" : "4999", "od" : 1 }, "highlight" : { "title" : [ "华为P40" ] } }, { "_index" : "goods", "_type" : "_doc", "_id" : "2", "_score" : 1.5241971, "_source" : { "title" : "华为Mate30", "content" : "华为Mate30 8+128G，麒麟990Soc", "price" : "3998", "od" : 2 }, "highlight" : { "title" : [ "华为Mate30" ] } } ] } }

例如百度搜索华为P40，不仅仅是title会高亮，content也会高亮，所以我们可以用multi_match+highlight实现

GET goods/_search { "query": { "multi_match": { "query": "华为P40", "fields": ["title","content"] } } , "highlight": { "pre_tags": "", "post_tags": "", "fields": { "title": {}, "content": {} } } }

{ "took" : 8, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 2.8157697, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "1", "_score" : 2.8157697, "_source" : { "title" : "华为P40", "content" : "华为P40 8+256G，麒麟990Soc，贼牛逼", "price" : "4999", "od" : 1 }, "highlight" : { "title" : [ "华为P40" ], "content" : [ "华为P40 8+256G，麒麟990Soc，贼牛逼" ] } }, { "_index" : "goods", "_type" : "_doc", "_id" : "2", "_score" : 1.8023796, "_source" : { "title" : "华为Mate30", "content" : "华为Mate30 8+128G，麒麟990Soc", "price" : "3998", "od" : 2 }, "highlight" : { "title" : [ "华为Mate30" ], "content" : [ "华为Mate30 8+128G，麒麟990Soc" ] } } ] } }

类似于MYSQL的and or

重点：must 代表and ，should 代表 or

must（and）的使用：

下面我们在must里面给了两个条件，如果这里是must，那就必须两个条件都要满足

GET goods/_search { "query": { "bool": { "must": [ { "match": { "title": "华为" } }, { "match": { "content": "MATE30" } } ] } } }

结果：

{ "took" : 10, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 2.9512205, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "2", "_score" : 2.9512205, "_source" : { "title" : "华为Mate30", "content" : "华为Mate30 8+128G，麒麟990Soc", "price" : "3998", "od" : 2 } } ] } }

should（or）的使用：

should里面同样有两个条件，但是只要满足一个就可以了

GET goods/_search { "query": { "bool": { "should": [ { "match": { "title": "华为" } }, { "match": { "content": "MATE30" } } ] } } }

结果：

{ "took" : 1, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 2.9512205, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "2", "_score" : 2.9512205, "_source" : { "title" : "华为Mate30", "content" : "华为Mate30 8+128G，麒麟990Soc", "price" : "3998", "od" : 2 } }, { "_index" : "goods", "_type" : "_doc", "_id" : "1", "_score" : 1.5241971, "_source" : { "title" : "华为P40", "content" : "华为P40 8+256G，麒麟990Soc，贼牛逼", "price" : "4999", "od" : 1 } } ] } }

比如我们要实现，输入title=xx，我们如果想得到price>4000作为一个条件，可以用到这个。

GET goods/_search { "query": { "bool": { "must": [ { "match": { "title": "小米" } } ],"filter": { "range": { "price": { "gt": 4000 } } } } } }

{ "took" : 1, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 2.4135482, "hits" : [ { "_index" : "goods", "_type" : "_doc", "_id" : "3", "_score" : 2.4135482, "_source" : { "title" : "小米11", "content" : "小米11 高通骁龙888Soc ,1亿像素", "price" : "4500", "od" : 3 } } ] } }

GET _cat/indices?v

elasticsearch的Java Api

1.导入elasticsearch高级客户端依赖和elasticsearch依赖（注意版本要和本机的es版本一致）,我们本机现在用的是7.6.1的es

org.elasticsearch.client elasticsearch-rest-high-level-client 7.6.1 org.elasticsearch elasticsearch 7.6.1 com.alibaba fastjson 1.2.75

2.打开RestHighLevelClient的构造器：

public RestHighLevelClient(RestClientBuilder restClientBuilder) { this(restClientBuilder, Collections.emptyList()); }

我们发现需要传入一个RestClientBuilder，但是这个对象我们需要通过RestClient来得到，而不是RestClientBuilder

3.打开RestClient：

public static RestClientBuilder builder(HttpHost... hosts) { if (hosts == null || hosts.length == 0) { throw new IllegalArgumentException("hosts must not be null nor empty"); } List nodes = Arrays.stream(hosts).map(Node::new).collect(Collectors.toList()); return new RestClientBuilder(nodes); }

我们发现RestClient的builder可以得到RestClientBuilder，然后我们点进去看HttpHost：

public HttpHost(String hostname, int port, String scheme) { //es所在主机名，es的端口号，协议（默认http） this.hostname = (String)Args.containsNoBlanks(hostname, "Host name"); this.lcHostname = hostname.toLowerCase(Locale.ROOT); if (scheme != null) { this.schemeName = scheme.toLowerCase(Locale.ROOT); } else { this.schemeName = "http"; } this.port = port; this.address = null; }

4.然后我们就配置好了如下：

HttpHost httpHost = new HttpHost("localhost",9200,"http"); RestClientBuilder restClientBuilder = RestClient.builder(httpHost); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(restClientBuilder);

5.为了方便，我们可以把这个RestHighLevelClient交给SpringIOC容器管理，后面我们自动注入即可

@Configuration public class esConfig { @Bean public RestHighLevelClient restHighLevelClient(){ HttpHost httpHost = new HttpHost("localhost",9200,"http"); RestClientBuilder builder = RestClient.builder(httpHost); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); return restHighLevelClient; } }

java elasticsearch api操作索引都是用restHighLevelClient.indices().xxxxx()的格式

//创建索引 @Test public void createIndex() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); //new一个创建索引请求，并传入一个创建的索引名称 CreateIndexRequest createIndexRequest = new CreateIndexRequest("java01"); //向es发送创建索引请求。 CreateIndexResponse createIndexResponse = restHighLevelClient.indices().create(createIndexRequest, RequestOptions.DEFAULT); restHighLevelClient.close(); }

//删除索引 @Test public void deleteIndex() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); //new一个删除索引请求，并传入需要删除的索引名称 DeleteIndexRequest deleteIndexRequest = new DeleteIndexRequest("java01"); //resthighLevelClient发送删除索引请求 restHighLevelClient.indices().delete(deleteIndexRequest,RequestOptions.DEFAULT); restHighLevelClient.close(); }

//检查索引是否存在 @Test public void indexExsit() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); GetIndexRequest getIndexRequest = new GetIndexRequest("goods"); boolean exists = restHighLevelClient.indices().exists(getIndexRequest, RequestOptions.DEFAULT); System.out.println(exists); }

//创建文档 @Test public void createIndexDoc() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); IndexRequest indexRequest = new IndexRequest("hello"); //指定文档id indexRequest.id("1"); /** * public IndexRequest source(Map source, XContentType contentType) throws ElasticsearchGenerationException { * try { * XContentBuilder builder = XContentFactory.contentBuilder(contentType); * builder.map(source); * return this.source(builder); * } catch (IOException var4) { * throw new ElasticsearchGenerationException("Failed to generate [" + source + "]", var4); * } * } * source有很多种方法，哪种都可以，我现在选的是Map的方法添加key:value */ Map source=new HashMap<>(); source.put("a_age","50"); source.put("a_address","广州"); //在es里面，一切皆为JSON，我们要把Map用fastjson转换成JSON字符串，XContentType指定为JSON类型 indexRequest.source(JSON.toJSONString(source), XContentType.JSON); IndexResponse response = restHighLevelClient.index(indexRequest, RequestOptions.DEFAULT); System.out.println("response:"+response); System.out.println("status:"+response.status()); }

//删除文档 @Test public void deleteDoc() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); DeleteRequest deleteRequest = new DeleteRequest("hello"); deleteRequest.id("1"); DeleteResponse delete = restHighLevelClient.delete(deleteRequest, RequestOptions.DEFAULT); System.out.println(delete.status()); }

//修改文档 @Test public void updateDoc() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); /** * 通过下面的方法去调用 * public UpdateRequest(String index, String id) { * super(index); * this.refreshPolicy = RefreshPolicy.NONE; * this.waitForActiveShards = ActiveShardCount.DEFAULT; * this.scriptedUpsert = false; * this.docAsUpsert = false; * this.detectNoop = true; * this.id = id; * } */ UpdateRequest updateRequest = new UpdateRequest("hello","1"); Map source=new HashMap<>(); source.put("a_address","河源"); updateRequest.doc(JSON.toJSONString(source),XContentType.JSON); UpdateResponse response = restHighLevelClient.update(updateRequest, RequestOptions.DEFAULT); System.out.println(response.status()); }

//获取文档 @Test public void getDoc() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); GetRequest getRequest = new GetRequest("hello"); getRequest.id("1"); GetResponse response = restHighLevelClient.get(getRequest, RequestOptions.DEFAULT); String sourceAsString = response.getSourceAsString(); System.out.println(sourceAsString); }

//搜索(匹配全文match_all) @Test public void search_matchAll() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); /** * public SearchRequest(String... indices) { * this(indices, new SearchSourceBuilder()); * } */ SearchRequest searchRequest = new SearchRequest("hello"); //相当于文本 SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder(); MatchAllQueryBuilder matchAllQueryBuilder = QueryBuilders.matchAllQuery(); searchSourceBuilder.query(matchAllQueryBuilder); //相当于search的query searchRequest.source(searchSourceBuilder); SearchResponse search = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT); SearchHit[] hits = search.getHits().getHits(); for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } }

//模糊搜索match @Test public void search_match() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); SearchRequest searchRequest = new SearchRequest(); //查询文本 SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder(); MatchQueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("a_address", "广州"); searchSourceBuilder.query(matchQueryBuilder); searchRequest.source(searchSourceBuilder); SearchResponse search = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT); SearchHit[] hits = search.getHits().getHits(); for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } }

//搜索(多字段搜索multi_match) @Test public void search_term() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); SearchRequest searchRequest = new SearchRequest("goods"); SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder(); searchSourceBuilder.query(QueryBuilders.multiMatchQuery("华为","title","content")); searchRequest.source(searchSourceBuilder); SearchResponse search = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT); SearchHit[] hits = search.getHits().getHits(); for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } }

fetchsource方法相当于_source

//fetchsource实现筛选字段(_source) @Test public void search_source() throws IOException { RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http")); RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder); SearchRequest searchRequest = new SearchRequest("goods"); SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder(); searchSourceBuilder.query(QueryBuilders.matchAllQuery()); /** * public SearchSourceBuilder fetchSource(@Nullable String[] includes, @Nullable String[] excludes) { * FetchSourceContext fetchSourceContext = this.fetchSourceContext != null ? this.fetchSourceContext : FetchSourceContext.FETCH_SOURCE; * this.fetchSourceContext = new FetchSourceContext(fetchSourceContext.fetchSource(), includes, excludes); * return this; * } * */ String[] includes={"title"}; //包含 String[] excludes={}; //排除 searchSourceBuilder.fetchSource(includes,excludes); searchRequest.source(searchSourceBuilder); SearchResponse search = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT); SearchHit[] hits = search.getHits().getHits(); for (SearchHit hit : hits) { System.out.println(hit.getSourceAsString()); } }

我们要把下面的es命令行代码转换成Java代码

GET goods/_search { "query": { "match": { "title": "华为" } },"sort": [ { "od": { "order": "desc" } } ] ,"from": 0, "size": 1, "highlight": { "pre_tags": "", "post_tags": "", "fields": { "title": {} } } }

Elasticsearch 分布式 实时流计算服务 CS 搜索引擎

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