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 {
    @Bean
    public 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);