ElasticSearch搜索引擎在JAVA中的简单使用

系统管理员 2024-02-18 22:09 18阅读 0赞

**Elasticsearch常用操作和核心原理见文章：**[https://blog.csdn.net/sdksdk0/article/details/78469190][https_blog.csdn.net_sdksdk0_article_details_78469190]  
**本文参照**：[https://www.2cto.com/kf/201802/719374.html][https_www.2cto.com_kf_201802_719374.html]  
**一、引入ElasticSearch的jar**  
  
org.elasticsearch  
elasticsearch  
2.4.0  
  
  
junit  
junit  
4.12  
  
  
com.fasterxml.jackson.core  
jackson-core  
2.8.1  
  
  
com.fasterxml.jackson.core  
jackson-databind  
2.8.1  
  
  
com.fasterxml.jackson.core  
jackson-annotations  
2.8.1  
  
**二、创建文档类型实体Bean**  
package cn.elasticsearch.domain;

public class Article \{  
private Integer id;  
private String title;  
private String content;

public Integer getId() {
        return id;
    }
    
    public void setId(Integer id) {
        this.id = id;
    }
    
    public String getTitle() {
        return title;
    }
    
    public void setTitle(String title) {
        this.title = title;
    }
    
    public String getContent() {
        return content;
    }
    
    public void setContent(String content) {
        this.content = content;
    }
    
    @Override
    public String toString() {
        return "Article [id=" + id + ", title=" + title + ", content="
                + content + "]";
    }

\}  
**三、ElasticSearch中建立文档，自动创建索引**  
// 直接在ElasticSearch中建立文档，自动创建索引  
@Test  
public void demo1() throws IOException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 创建对象要添加对象的JSON格式字符串
        XContentBuilder builder = XContentFactory.jsonBuilder().startObject()
                .field("1", 1)
                .field("title", "ElasticSearch是一个基于Lucene的搜索服务器")
                .field("content", "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。")
                .endObject();
    
        // 建立文档对象
        client.prepareIndex("blog1", "article", "1").setSource(builder).get();
    
        // 关闭连接
        client.close();
    }

**四、QueryBuilders.matchAllQuery() 查询所有**  
// 搜索在ElasticSearch中创建的文档对象，使用QueryBuilders.matchAllQuery()查询所有  
@Test  
public void demo2() throws UnknownHostException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 手册数据
        SearchResponse searchResponse = client
                .prepareSearch("blog1")
                .setTypes("article")
                .setQuery(QueryBuilders.matchAllQuery()).get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }

**五、QueryBuilders.queryStringQuery() 分词内容查询**  
// 使用QueryBuilders.queryStringQuery(搜索内容)进行分词内容查询  
@Test  
public void demo3() throws UnknownHostException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 搜索数据
        SearchResponse searchResponse = client
                .prepareSearch("blog1")
                .setTypes("article")
                .setQuery(QueryBuilders.queryStringQuery("全文")).get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }

**六、QueryBuilders.wildcardQuery() 范围分词模糊查询**  
// 使用QueryBuilders.wildcardQuery(“搜索范围:如title|content”,”查询内容”)进行范围分词模糊查询  
// \*表示任意字符串 ?表示任意字符  
// 查询结果为0条，说明没有词条包含”全文”  
@Test  
public void demo4() throws UnknownHostException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 搜索数据
    SearchResponse searchResponse = client
            .prepareSearch("blog1")
            .setTypes("article")
            .setQuery(QueryBuilders.wildcardQuery("content", "*全文*")).get();
    
    printSearchResponse(searchResponse);
    
    // 关闭连接
    client.close();

\}  
**七、QueryBuilders.termQuery() 范围词条查询**  
// 使用QueryBuilders.termQuery(“搜索范围:如title|content”,”查询内容”)进行范围词条查询  
// 查询结果为0条，说明没有”搜索”这个词条  
@Test  
public void demo5() throws UnknownHostException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 搜索数据
    SearchResponse searchResponse = client
            .prepareSearch("blog2")
            .setTypes("article")
            .setQuery(QueryBuilders.termQuery("content", "搜")).get();
    
    printSearchResponse(searchResponse);
    
    // 关闭连接
    client.close();

**八、创建/删除索引**  
// 索引操作 — 创建与删除  
@Test  
public void demo6() throws UnknownHostException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 创建索引
    client.admin().indices().prepareCreate("blog2").get();
    
    // 删除索引
    //client.admin().indices().prepareDelete("blog2").get();
    
    // 关闭连接
    client.close();

\}  
**九、创建映射**  
// 映射操作 — 创建  
@Test  
public void demo7() throws IOException, ExecutionException, InterruptedException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 添加映射
    XContentBuilder builder = XContentFactory.jsonBuilder()
            .startObject()
            .startObject("article")
            .startObject("properties")
            .startObject("id").field("type", "integer").field("store", "yes").endObject()
            .startObject("title").field("type", "string").field("store", "yes").field("analyzer", "ik").endObject()
            .startObject("content").field("type", "string").field("store", "yes").field("analyzer", "ik").endObject()
            .endObject()
            .endObject()
            .endObject();
    
    PutMappingRequest mapping = Requests.putMappingRequest("blog2")
            .type("article").source(builder);
    client.admin().indices().putMapping(mapping).get();
    
    // 关闭连接
    client.close();

\}  
**十、创建文档**  
// 文档操作 — 创建  
@Test  
public void demo8() throws IOException, ExecutionException, InterruptedException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 创建jackson解析对象
    ObjectMapper objectMapper = new ObjectMapper();
    
    for (int i = 1;i <= 100;i++){
        // 描述json 数据
        /*
         * {id:xxx, title:xxx, content:xxx}
         */
        Article article = new Article();
        article.setId(i);
        article.setTitle(i + "搜索工作其实很难的");
        article.setContent(i + "我们希望我们的搜索解决方案要快，我们希望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的索引数据，我们希望我们的搜索服务器始终可用，我们希望能够一台开始并扩展到数百，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。Elasticsearch旨在解决所有这些问题和更多的问题。");
    
        // 建立文档
        client.prepareIndex("blog2", "article", article.getId().toString())
                .setSource(objectMapper.writeValueAsString(article)).get();
    }
    
    // 关闭连接
    client.close();

\}  
**十一、分页搜索**  
// 分页搜索  
@Test  
public void demo11() throws UnknownHostException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 搜索数据
    SearchRequestBuilder searchRequestBuilder = client.prepareSearch("blog2")
            .setTypes("article")
            .setQuery(QueryBuilders.matchAllQuery());
    
    // 通过SearchRequestBuilder的setFrom和setSize方法实现分页
    // 显示第二页的数据，每页显示20条
    searchRequestBuilder.setFrom(2);
    searchRequestBuilder.setSize(20);
    
    SearchResponse searchResponse = searchRequestBuilder.get();
    
    printSearchResponse(searchResponse);
    
    // 关闭连接
    client.close();

\}  
**十二、高亮显示**  
// 高亮显示  
@Test  
public void demo12() throws IOException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

ObjectMapper objectMapper = new ObjectMapper();
    
    // 搜索数据
    SearchRequestBuilder searchRequestBuilder = client.prepareSearch("blog2")
            .setTypes("article")
            .setQuery(QueryBuilders.termQuery("title","搜索"));
    
    // 高亮应用的内容
    searchRequestBuilder.addHighlightedField("title"); // 对title字段进行高亮
    searchRequestBuilder.setHighlighterPreTags("<em>"); // 前置元素
    searchRequestBuilder.setHighlighterPostTags("</em>"); // 后置元素
    
    // 通过SearchRequestBuilder的setFrom和setSize方法实现分页
    // 显示第二页的数据，每页显示20条
    searchRequestBuilder.setFrom(2).setSize(20);
    
    SearchResponse searchResponse = searchRequestBuilder.get();
    
    // 获取命中次数，查询结果又多少对象
    SearchHits hits = searchResponse.getHits();
    System.out.println("查询结果有:" + hits.getTotalHits() + "条");
    Iterator<searchhit> iterator = hits.iterator();
    while (iterator.hasNext()) {
        SearchHit searchHit = iterator.next(); //每个查询对象
    
        // 将高亮处理后的内容，替换原有高亮内容(原有内容，可能会出现显示不全)
        Map<string,highlightfield> highlightFields = searchHit.getHighlightFields();
        HighlightField titleField = highlightFields.get("title");
        // 获取到原有内容中的每个高亮显示的集中的位置，fragment就是高亮片段
        Text[] fragments = titleField.fragments();
        String title = "";
        for (Text text : fragments){
            title += text;
        }
    
        // 通过ObjectMapper的readVallue将查询结果转换成Article对象
        Article article = objectMapper.readValue(searchHit.getSourceAsString(), Article.class);
    
        // 用高亮后内容，替换原有内容
        article.setTitle(title);
    
        System.out.println(article);
    }
    
    // 关闭连接
    client.close();

\}  
**十三、文档修改**  
// 文档操作 — 修改  
@Test  
public void demo9() throws IOException, ExecutionException, InterruptedException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

// 描述json 数据
    /*
     * {id:xxx, title:xxx, content:xxx}
     */
    Article article = new Article();
    article.setId(2);
    article.setTitle("搜索工作其实也不难");
    article.setContent("我们希望我们的搜索解决方案要快，我们希望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的索引数据，我们希望我们的搜索服务器始终可用，我们希望能够一台开始并扩展到数百，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。Elasticsearch旨在解决所有这些问题和更多的问题。");
    
    // 创建jackson解析对象
    ObjectMapper objectMapper = new ObjectMapper();
    
    // 修改文档 --- 方式一
    //client.prepareUpdate("blog2", "article", article.getId().toString())
    //        .setDoc(objectMapper.writeValueAsString(article)).get();
    
    // 修改文档 --- 方式二
    client.update(
            new UpdateRequest("blog2", "article", article.getId().toString())
                    .doc(objectMapper.writeValueAsString(article))
    ).get();
    
    // 关闭连接
    client.close();

\}  
**十四、文档删除**  
// 文档操作 — 删除  
@Test  
public void demo10() throws IOException, ExecutionException, InterruptedException \{  
// 创建ElasticSearch连接对象  
Client client = getElasticSearchClient();

Article article = new Article();
    article.setId(2);
    
    // 删除文档 --- 方式一
    //client.prepareDelete("blog2", "article", article.getId().toString()).get();
    
    // 删除文档 --- 方式二
    client.delete(
            new DeleteRequest("blog2", "article", article.getId().toString())
    ).get();
    
    // 关闭连接
    client.close();

\}  
**完整代码：**  
package cn.elasticsearch.test;

import cn.elasticsearch.domain.Article;  
import com.fasterxml.jackson.databind.ObjectMapper;  
import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;  
import org.elasticsearch.action.delete.DeleteRequest;  
import org.elasticsearch.action.search.SearchRequestBuilder;  
import org.elasticsearch.action.search.SearchResponse;  
import org.elasticsearch.action.update.UpdateRequest;  
import org.elasticsearch.client.Client;  
import org.elasticsearch.client.Requests;  
import org.elasticsearch.client.transport.TransportClient;  
import org.elasticsearch.common.text.Text;  
import org.elasticsearch.common.transport.InetSocketTransportAddress;  
import org.elasticsearch.common.xcontent.XContentBuilder;  
import org.elasticsearch.common.xcontent.XContentFactory;  
import org.elasticsearch.index.query.QueryBuilders;  
import org.elasticsearch.search.SearchHit;  
import org.elasticsearch.search.SearchHits;  
import org.elasticsearch.search.highlight.HighlightField;  
import org.junit.Test;

import java.io.IOException;  
import java.net.InetAddress;  
import java.net.UnknownHostException;  
import java.util.Iterator;  
import java.util.Map;  
import java.util.concurrent.ExecutionException;

// ElasticSearch 测试程序  
public class ElasticSearchTest \{

// 直接在ElasticSearch中建立文档，自动创建索引
    @Test
    public void demo1() throws IOException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 创建对象要添加对象的JSON格式字符串
        XContentBuilder builder = XContentFactory.jsonBuilder().startObject()
                .field("1", 1)
                .field("title", "ElasticSearch是一个基于Lucene的搜索服务器")
                .field("content", "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。")
                .endObject();
    
        // 建立文档对象
        client.prepareIndex("blog1", "article", "1").setSource(builder).get();
    
        // 关闭连接
        client.close();
    }
    
    
    // 搜索在ElasticSearch中创建的文档对象，使用QueryBuilders.matchAllQuery()查询所有
    @Test
    public void demo2() throws UnknownHostException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 手册数据
        SearchResponse searchResponse = client
                .prepareSearch("blog1")
                .setTypes("article")
                .setQuery(QueryBuilders.matchAllQuery()).get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }
    
    // 使用QueryBuilders.queryStringQuery(搜索内容)进行分词内容查询
    @Test
    public void demo3() throws UnknownHostException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 搜索数据
        SearchResponse searchResponse = client
                .prepareSearch("blog1")
                .setTypes("article")
                .setQuery(QueryBuilders.queryStringQuery("全文")).get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }
    
    // 使用QueryBuilders.wildcardQuery("搜索范围:如title|content","查询内容")进行范围分词模糊查询
    // *表示任意字符串     ?表示任意字符
    // 查询结果为0条，说明没有词条包含"全文"
    @Test
    public void demo4() throws UnknownHostException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 搜索数据
        SearchResponse searchResponse = client
                .prepareSearch("blog1")
                .setTypes("article")
                .setQuery(QueryBuilders.wildcardQuery("content", "*全文*")).get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }
    
    // 使用QueryBuilders.termQuery("搜索范围:如title|content","查询内容")进行范围词条查询
    // 查询结果为0条，说明没有"搜索"这个词条
    @Test
    public void demo5() throws UnknownHostException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 搜索数据
        SearchResponse searchResponse = client
                .prepareSearch("blog2")
                .setTypes("article")
                .setQuery(QueryBuilders.termQuery("content", "搜")).get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }
    
    // 索引操作 --- 创建与删除
    @Test
    public void demo6() throws UnknownHostException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 创建索引
        client.admin().indices().prepareCreate("blog2").get();
    
        // 删除索引
        //client.admin().indices().prepareDelete("blog2").get();
    
        // 关闭连接
        client.close();
    }
    
    // 映射操作 --- 创建
    @Test
    public void demo7() throws IOException, ExecutionException, InterruptedException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 添加映射
        XContentBuilder builder = XContentFactory.jsonBuilder()
                .startObject()
                .startObject("article")
                .startObject("properties")
                .startObject("id").field("type", "integer").field("store", "yes").endObject()
                .startObject("title").field("type", "string").field("store", "yes").field("analyzer", "ik").endObject()
                .startObject("content").field("type", "string").field("store", "yes").field("analyzer", "ik").endObject()
                .endObject()
                .endObject()
                .endObject();
    
        PutMappingRequest mapping = Requests.putMappingRequest("blog2")
                .type("article").source(builder);
        client.admin().indices().putMapping(mapping).get();
    
        // 关闭连接
        client.close();
    }
    
    // 文档操作 --- 创建
    @Test
    public void demo8() throws IOException, ExecutionException, InterruptedException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 创建jackson解析对象
        ObjectMapper objectMapper = new ObjectMapper();
    
        for (int i = 1;i <= 100;i++){
            // 描述json 数据
            /*
             * {id:xxx, title:xxx, content:xxx}
             */
            Article article = new Article();
            article.setId(i);
            article.setTitle(i + "搜索工作其实很难的");
            article.setContent(i + "我们希望我们的搜索解决方案要快，我们希望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的索引数据，我们希望我们的搜索服务器始终可用，我们希望能够一台开始并扩展到数百，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。Elasticsearch旨在解决所有这些问题和更多的问题。");
    
            // 建立文档
            client.prepareIndex("blog2", "article", article.getId().toString())
                    .setSource(objectMapper.writeValueAsString(article)).get();
        }
    
        // 关闭连接
        client.close();
    }
    
    // 分页搜索
    @Test
    public void demo11() throws UnknownHostException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 搜索数据
        SearchRequestBuilder searchRequestBuilder = client.prepareSearch("blog2")
                .setTypes("article")
                .setQuery(QueryBuilders.matchAllQuery());
    
        // 通过SearchRequestBuilder的setFrom和setSize方法实现分页
        // 显示第二页的数据，每页显示20条
        searchRequestBuilder.setFrom(2);
        searchRequestBuilder.setSize(20);
    
        SearchResponse searchResponse = searchRequestBuilder.get();
    
        printSearchResponse(searchResponse);
    
        // 关闭连接
        client.close();
    }
    
    // 高亮显示
    @Test
    public void demo12() throws IOException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        ObjectMapper objectMapper = new ObjectMapper();
    
        // 搜索数据
        SearchRequestBuilder searchRequestBuilder = client.prepareSearch("blog2")
                .setTypes("article")
                .setQuery(QueryBuilders.termQuery("title","搜索"));
    
        // 高亮应用的内容
        searchRequestBuilder.addHighlightedField("title"); // 对title字段进行高亮
        searchRequestBuilder.setHighlighterPreTags("<em>"); // 前置元素
        searchRequestBuilder.setHighlighterPostTags("</em>"); // 后置元素
    
        // 通过SearchRequestBuilder的setFrom和setSize方法实现分页
        // 显示第二页的数据，每页显示20条
        searchRequestBuilder.setFrom(2).setSize(20);
    
        SearchResponse searchResponse = searchRequestBuilder.get();
    
        // 获取命中次数，查询结果又多少对象
        SearchHits hits = searchResponse.getHits();
        System.out.println("查询结果有:" + hits.getTotalHits() + "条");
        Iterator<searchhit> iterator = hits.iterator();
        while (iterator.hasNext()) {
            SearchHit searchHit = iterator.next(); //每个查询对象
    
            // 将高亮处理后的内容，替换原有高亮内容(原有内容，可能会出现显示不全)
            Map<string,highlightfield> highlightFields = searchHit.getHighlightFields();
            HighlightField titleField = highlightFields.get("title");
            // 获取到原有内容中的每个高亮显示的集中的位置，fragment就是高亮片段
            Text[] fragments = titleField.fragments();
            String title = "";
            for (Text text : fragments){
                title += text;
            }
    
            // 通过ObjectMapper的readVallue将查询结果转换成Article对象
            Article article = objectMapper.readValue(searchHit.getSourceAsString(), Article.class);
    
            // 用高亮后内容，替换原有内容
            article.setTitle(title);
    
            System.out.println(article);
        }
    
        // 关闭连接
        client.close();
    }
    
    // 文档操作 --- 修改
    @Test
    public void demo9() throws IOException, ExecutionException, InterruptedException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        // 描述json 数据
        /*
         * {id:xxx, title:xxx, content:xxx}
         */
        Article article = new Article();
        article.setId(2);
        article.setTitle("搜索工作其实也不难");
        article.setContent("我们希望我们的搜索解决方案要快，我们希望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的索引数据，我们希望我们的搜索服务器始终可用，我们希望能够一台开始并扩展到数百，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。Elasticsearch旨在解决所有这些问题和更多的问题。");
    
        // 创建jackson解析对象
        ObjectMapper objectMapper = new ObjectMapper();
    
        // 修改文档 --- 方式一
        //client.prepareUpdate("blog2", "article", article.getId().toString())
        //        .setDoc(objectMapper.writeValueAsString(article)).get();
    
        // 修改文档 --- 方式二
        client.update(
                new UpdateRequest("blog2", "article", article.getId().toString())
                        .doc(objectMapper.writeValueAsString(article))
        ).get();
    
        // 关闭连接
        client.close();
    }
    
    // 文档操作 --- 删除
    @Test
    public void demo10() throws IOException, ExecutionException, InterruptedException {
        // 创建ElasticSearch连接对象
        Client client = getElasticSearchClient();
    
        Article article = new Article();
        article.setId(2);
    
        // 删除文档 --- 方式一
        //client.prepareDelete("blog2", "article", article.getId().toString()).get();
    
        // 删除文档 --- 方式二
        client.delete(
                new DeleteRequest("blog2", "article", article.getId().toString())
        ).get();
    
        // 关闭连接
        client.close();
    }
    
    // 遍历打印查询后的结果
    private void printSearchResponse(SearchResponse searchResponse) {
        // 获取命中次数，查询结果又多少对象
        SearchHits hits = searchResponse.getHits();
        System.out.println("查询结果有:" + hits.getTotalHits() + "条");
        Iterator<searchhit> iterator = hits.iterator();
        while (iterator.hasNext()) {
            SearchHit searchHit = iterator.next(); //每个查询对象
            System.out.println(searchHit.getSourceAsString()); //获取字符串格式并打印
            System.out.println("title:" + searchHit.getSource().get("title"));
        }
    }
    
    // 获取ElasticSearcch Client对象
    private Client getElasticSearchClient() throws UnknownHostException {
        return TransportClient
                .builder()
                .build()
                .addTransportAddress(
                        new InetSocketTransportAddress(
                                InetAddress.getByName("127.0.0.1"), 9300));
    }

[https_blog.csdn.net_sdksdk0_article_details_78469190]: https://blog.csdn.net/sdksdk0/article/details/78469190
[https_www.2cto.com_kf_201802_719374.html]: https://www.2cto.com/kf/201802/719374.html