1. ElasticSearch

1.1 倒排索引 

1.2 ElasticSearch和Mysql对比 

 1.3 RestClient操作

导入依赖

        <dependency><groupId>org.elasticsearch.client</groupId><artifactId>elasticsearch-rest-high-level-client</artifactId><version>7.15.0</version></dependency>

并设置 

<elasticsearch.version>7.15.0</elasticsearch.version>

添加ElasticSearch配置

@Configuration
public class ElasticSearchConfig {@Beanpublic RestHighLevelClient restHighLevelClient(){RestHighLevelClient client=new RestHighLevelClient(RestClient.builder(new HttpHost("127.0.0.1",9200,"http")));return client;}
}

索引的创建，判断是否存在，删除

  CreateIndexRequest createIndexRequest=new CreateIndexRequest("test");restHighLevelClient.indices().create(createIndexRequest, RequestOptions.DEFAULT);//判断某个索引库是否存在GetIndexRequest getIndexRequest=new GetIndexRequest("test");boolean exists = restHighLevelClient.indices().exists(getIndexRequest, RequestOptions.DEFAULT);System.out.println(exists);//删除某个索引库DeleteIndexRequest deleteIndexRequest=new DeleteIndexRequest("test");restHighLevelClient.indices().delete(deleteIndexRequest,RequestOptions.DEFAULT);

添加文档

  IndexRequest in = new IndexRequest("test").id("1").source("{\n" +"   \"username\":\"admin\",\n" +"   \"password\":\"admin\"\n" +"}", XContentType.JSON);restHighLevelClient.index(in,RequestOptions.DEFAULT);

查找文档

 GetRequest getRequest=new GetRequest("test","1");GetResponse getResponse = restHighLevelClient.get(getRequest, RequestOptions.DEFAULT);System.out.println(getResponse.getSourceAsString());

更新文档

//全量更新，再次写入id一样的文档，就会删除旧文档，添加新文档IndexRequest in = new IndexRequest("test").id("1").source("{\n" +"   \"username\":\"admin\",\n" +"   \"password\":\"helloworld\"\n" +"}", XContentType.JSON);restHighLevelClient.index(in,RequestOptions.DEFAULT);UpdateRequest updateRequest=new UpdateRequest("test","1");updateRequest.doc("password","hello");restHighLevelClient.update(updateRequest,RequestOptions.DEFAULT);

删除文档

  DeleteRequest deleteRequest=new DeleteRequest("test","1");restHighLevelClient.delete(deleteRequest,RequestOptions.DEFAULT);

批量导入文档

  BulkRequest bulkRequest=new BulkRequest();bulkRequest.add(new IndexRequest("test").id("2").source("{\n" +"   \"username\":\"hello\",\n" +"   \"password\":\"hello\"\n" +"}",XContentType.JSON));bulkRequest.add(new IndexRequest("test").id("3").source("{\n" +"   \"username\":\"world\",\n" +"   \"password\":\"world\"\n" +"}",XContentType.JSON));restHighLevelClient.bulk(bulkRequest,RequestOptions.DEFAULT);