Spring Data Elasticsearch--ElasticsearchRestTemplate--使用/教程/实例

拼搏现实的明天。 2022-09-15 11:59 521阅读 0赞

原文网址：[Spring Data Elasticsearch--ElasticsearchRestTemplate--使用/教程/实例\_IT利刃出鞘的博客-CSDN博客][Spring Data Elasticsearch--ElasticsearchRestTemplate--_IT_-CSDN]

# 简介 #

**说明**

本文用实例来介绍如何使用Spring Data Elasticsearch的ElasticsearchRestTemplate来操作ES。包括：索引的增删等、文档的增删改查、文档的动态查询（或者说：多条件查询、复杂查询）。

动态查询的含义：查询条件有多个时，某个查询条件可能有也可能没有，这时就需要手动判断，如果为空则不拼装搜索条件。

本文用博客的业务进行示例。索引名：blog，里边有标题、内容、作者、创建时间等。

**官网**

[Elasticsearch Operations][]

**为什么用ElasticsearchRestTemplate**

在Spring Data Elasticsearch4.0之后，ElasticsearchRepository里边大部分搜索方法都已经被标记为废弃，注释中让我们用两种方法来操作：

1.  在方法上使用@Query自定义DSL。
2.  使用 ElasticsearchOperations来操作。

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16][]

使用@Query自定义DSL不支持动态查询，其用法见：[Spring Data Elasticsearch--入门/使用/用法/实例/教程/客户端--SpringBoot整合\_IT利刃出鞘的博客-CSDN博客][Spring Data Elasticsearch--_--SpringBoot_IT_-CSDN]

ElasticsearchOperations支持动态查询，ElasticsearchRestTemplate是ElasticsearchOperations的实现类。

# 公共代码 #

## 依赖及配置 ##

**依赖**

主要是spring-boot-starter-data-elasticsearch这个依赖：

<dependency>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-data-elasticsearch</artifactId>
    </dependency>

**配置**

spring:
      elasticsearch:
        rest:
          uris: http://127.0.0.1:9200
          # username: xxx
          # password: yyy
          # connection-timeout: 1
          # read-timeout: 30
    
    # 上边是客户端High Level REST Client的配置，推荐使用。
    
    # 下边是reactive客户端的配置，非官方，不推荐。
    #  data:
    #    elasticsearch:
    #      client:
    #        reactive:
    #          endpoints: 127.0.0.1:9200
    #          username: xxx
    #          password: yyy
    #          connection-timeout: 1
    #          socket-timeout: 30
    #          use-ssl: false

**整个pom.xml**

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.3.12.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>com.example</groupId>
        <artifactId>demo_spring-data-elasticsearch</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>demo_spring-data-elasticsearch</name>
        <description>demo_spring-data-elasticsearch</description>
        <properties>
            <java.version>1.8</java.version>
        </properties>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
    
            <dependency>
                <groupId>com.github.xiaoymin</groupId>
                <artifactId>knife4j-spring-boot-starter</artifactId>
                <version>3.0.3</version>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <excludes>
                            <exclude>
                                <groupId>org.projectlombok</groupId>
                                <artifactId>lombok</artifactId>
                            </exclude>
                        </excludes>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    
    </project>

## 索引结构及数据 ##

**索引结构**

http://localhost:9200/  
PUT blog

{
        "mappings": {
            "properties": {
                "id":{
                    "type":"long"
                },
                "title": {
                    "type": "text"
                },
                "content": {
                    "type": "text"
                },
                "author":{
                    "type": "text",
                    "fields": {
                        "keyword": {
                            "type": "keyword"
                        }
                    }
                },
                "category":{
                    "type": "keyword"
                },
                "createTime": {
                    "type": "date",
                    "format":"yyyy-MM-dd HH:mm:ss.SSS||yyyy-MM-dd'T'HH:mm:ss.SSS||yyyy-MM-dd HH:mm:ss||epoch_millis"
                },
                "updateTime": {
                    "type": "date",
                    "format":"yyyy-MM-dd HH:mm:ss.SSS||yyyy-MM-dd'T'HH:mm:ss.SSS||yyyy-MM-dd HH:mm:ss||epoch_millis"
                },
                "status":{
                    "type":"integer"
                },
                "serialNum": {
                    "type": "keyword"
                }
            }
        }
    }

**数据**

*  每个文档必须独占一行，不能换行。
 *  此命令要放到postman中去执行，如果用head执行会失败

http://localhost:9200/  
POST \_bulk

{"index":{"_index":"blog","_id":1}}
    {"blogId":1,"title":"Spring Data ElasticSearch学习教程1","content":"这是批量添加的文档1","author":"Iron Man","category":"ElasticSearch","status":1,"serialNum":"1","createTime":"2021-10-10 11:52:01.249","updateTime":null}
    {"index":{"_index":"blog","_id":2}}
    {"blogId":2,"title":"Spring Data ElasticSearch学习教程2","content":"这是批量添加的文档2","author":"Iron Man","category":"ElasticSearch","status":1,"serialNum":"2","createTime":"2021-10-10 11:52:02.249","updateTime":null}
    {"index":{"_index":"blog","_id":3}}
    {"blogId":3,"title":"Spring Data ElasticSearch学习教程3","content":"这是批量添加的文档3","author":"Captain America","category":"ElasticSearch","status":1,"serialNum":"3","createTime":"2021-10-10 11:52:03.249","updateTime":null}
    {"index":{"_index":"blog","_id":4}}
    {"blogId":4,"title":"Spring Data ElasticSearch学习教程4","content":"这是批量添加的文档4","author":"Captain America","category":"ElasticSearch","status":1,"serialNum":"4","createTime":"2021-10-10 11:52:04.249","updateTime":null}
    {"index":{"_index":"blog","_id":5}}
    {"blogId":5,"title":"Spring Data ElasticSearch学习教程5","content":"这是批量添加的文档5","author":"Spider Man","category":"ElasticSearch","status":1,"serialNum":"5","createTime":"2021-10-10 11:52:05.249","updateTime":null}
    {"index":{"_index":"blog","_id":6}}
    {"blogId":6,"title":"Java学习教程6","content":"这是批量添加的文档6","author":"Spider Man","category":"ElasticSearch","status":1,"serialNum":"6","createTime":"2021-10-10 11:52:06.249","updateTime":null}
    {"index":{"_index":"blog","_id":7}}
    {"blogId":7,"title":"Java学习教程7","content":"这是批量添加的文档7","author":"Iron Man","category":"ElasticSearch","status":1,"serialNum":"7","createTime":"2021-10-10 11:52:07.249","updateTime":null}
    {"index":{"_index":"blog","_id":8}}
    {"blogId":8,"title":"Java学习教程8","content":"这是批量添加的文档8","author":"Iron Man","category":"ElasticSearch","status":1,"serialNum":"8","createTime":"2021-10-10 11:52:08.249","updateTime":null}
    {"index":{"_index":"blog","_id":9}}
    {"blogId":9,"title":"Java学习教程9","content":"这是批量添加的文档9","author":"Captain America","category":"ElasticSearch","status":1,"serialNum":"9","createTime":"2021-10-10 11:52:09.249","updateTime":null}
    {"index":{"_index":"blog","_id":10}}
    {"blogId":10,"title":"Java学习教程10","content":"这是批量添加的文档10","author":"God Of Thunder","category":"ElasticSearch","status":1,"serialNum":"10","createTime":"2021-10-10 11:52:10.249","updateTime":null}

执行后的结果

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

# 索引操作（IndexOperations） #

本处只是展示索引的操作方法，项目中不会这样创建索引，而是手写DSL去创建。

package com.example.demo.controller;
    
    import com.example.demo.entity.Blog;
    import io.swagger.annotations.Api;
    import io.swagger.annotations.ApiOperation;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * 本处只是展示索引的操作方法，项目中不会这样创建索引，而是手写DSL去创建。
     */
    @Api(tags = "索引操作（用不到）")
    @RestController
    @RequestMapping("indexViaRestTemplate")
    public class IndexViaRestTemplateController {
        @Autowired
        private ElasticsearchRestTemplate elasticsearchRestTemplate;
    
    
        @ApiOperation("创建索引")
        @PostMapping("createIndex")
        public String createIndex() {
            // 创建索引，会根据Blog类的@Document注解信息来创建
            elasticsearchRestTemplate.createIndex(Blog.class);
    
            // 配置映射，会根据Item类中的id、Field等字段来自动完成映射
            elasticsearchRestTemplate.putMapping(Blog.class);
            return "success";
        }
    
        @ApiOperation("创建索引")
        @PostMapping("deleteIndex")
        public String deleteIndex() {
            // 删除索引，会根据Blog类的@Document注解信息来删除
            elasticsearchRestTemplate.deleteIndex(Blog.class);
            return "success";
        }
    }

# 文档操作（DocumentOperations） #

本处介绍常用的一些方法，这些方法能够满足开发中所有需求：

1.  添加单个文档
2.  添加多个文档
3.  修改单个文档数据
4.  修改单个文档部分数据
5.  修改多个文档部分数据
6.  查看单个文档
7.  删除单个文档(根据id)
8.  删除单个文档(根据条件)
9.  删除所有文档。

package com.example.demo.controller;
    
    import com.example.demo.entity.Blog;
    import io.swagger.annotations.Api;
    import io.swagger.annotations.ApiOperation;
    import org.elasticsearch.index.query.QueryBuilders;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
    import org.springframework.data.elasticsearch.core.document.Document;
    import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
    import org.springframework.data.elasticsearch.core.query.NativeSearchQuery;
    import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
    import org.springframework.data.elasticsearch.core.query.UpdateQuery;
    import org.springframework.data.elasticsearch.core.query.UpdateResponse;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    
    @Api(tags = "增删改查（RestTemplate方式）")
    @RestController
    @RequestMapping("crudViaRestTemplate")
    public class CrudViaRestTemplateController {
        @Autowired
        private ElasticsearchRestTemplate elasticsearchRestTemplate;
    
        @ApiOperation("添加单个文档")
        @PostMapping("addDocument")
        public Blog addDocument() {
            Long id = 1L;
            Blog blog = new Blog();
            blog.setBlogId(id);
            blog.setTitle("Spring Data ElasticSearch学习教程" + id);
            blog.setContent("这是添加单个文档的实例" + id);
            blog.setAuthor("Tony");
            blog.setCategory("ElasticSearch");
            blog.setCreateTime(new Date());
            blog.setStatus(1);
            blog.setSerialNum(id.toString());
    
            return elasticsearchRestTemplate.save(blog);
        }
    
        @ApiOperation("添加多个文档")
        @PostMapping("addDocuments")
        public Object addDocuments(Integer count) {
            List<Blog> blogs = new ArrayList<>();
            for (int i = 1; i <= count; i++) {
                Long id = (long)i;
                Blog blog = new Blog();
                blog.setBlogId(id);
                blog.setTitle("Spring Data ElasticSearch学习教程" + id);
                blog.setContent("这是添加单个文档的实例" + id);
                blog.setAuthor("Tony");
                blog.setCategory("ElasticSearch");
                blog.setCreateTime(new Date());
                blog.setStatus(1);
                blog.setSerialNum(id.toString());
                blogs.add(blog);
            }
    
            return elasticsearchRestTemplate.save(blogs);
        }
    
        /**
         * 跟新增是同一个方法。若id已存在，则修改。
         * 无法只修改某个字段，只能覆盖所有字段。若某个字段没有值，则会写入null。
         * @return 成功写入的数据
         */
        @ApiOperation("修改单个文档数据")
        @PostMapping("editDocument")
        public Blog editDocument() {
            Long id = 1L;
            Blog blog = new Blog();
            blog.setBlogId(id);
            blog.setTitle("Spring Data ElasticSearch学习教程" + id);
            blog.setContent("这是修改单个文档的实例" + id);
    
            return elasticsearchRestTemplate.save(blog);
        }
    
        @ApiOperation("修改单个文档部分数据")
        @PostMapping("editDocumentPart")
        public UpdateResponse editDocumentPart() {
            long id = 1L;
    
            Document document = Document.create();
            document.put("title", "修改后的标题" + id);
            document.put("content", "修改后的内容" + id);
    
            UpdateQuery updateQuery = UpdateQuery.builder(Long.toString(id))
                    .withDocument(document)
                    .build();
    
            UpdateResponse response = elasticsearchRestTemplate.update(updateQuery, IndexCoordinates.of("blog"));
    
            return response;
        }
    
        @ApiOperation("修改多个文档部分数据")
        @PostMapping("editDocumentsPart")
        public void editDocumentsPart(int count) {
            List<UpdateQuery> updateQueryList = new ArrayList<>();
            for (int i = 1; i <= count; i++) {
                long id = (long) i;
                Document document = Document.create();
                document.put("title", "修改后的标题" + id);
                document.put("content", "修改后的内容" + id);
                UpdateQuery updateQuery = UpdateQuery.builder(Long.toString(id))
                        .withDocument(document)
                        .build();
                updateQueryList.add(updateQuery);
            }
    
            elasticsearchRestTemplate.bulkUpdate(updateQueryList, IndexCoordinates.of("blog"));
        }
    
        @ApiOperation("查看单个文档")
        @GetMapping("findById")
        public Blog findById(Long id) {
    
            return elasticsearchRestTemplate.get(
                    id.toString(), Blog.class, IndexCoordinates.of("blog"));
        }
    
        @ApiOperation("删除单个文档(根据id)")
        @PostMapping("deleteDocumentById")
        public String deleteDocumentById(Long id) {
            return elasticsearchRestTemplate.delete(id.toString(), Blog.class);
        }
    
        @ApiOperation("删除单个文档(根据条件)")
        @PostMapping("deleteDocumentByQuery")
        public void deleteDocumentByQuery(String title) {
            NativeSearchQuery nativeSearchQuery = new NativeSearchQueryBuilder()
                    .withQuery(QueryBuilders.matchQuery("title", title))
                    .build();
    
            elasticsearchRestTemplate.delete(nativeSearchQuery, Blog.class, IndexCoordinates.of("blog"));
        }
    
        @ApiOperation("删除所有文档")
        @PostMapping("deleteDocumentAll")
        public void deleteDocumentAll() {
            NativeSearchQuery nativeSearchQuery = new NativeSearchQueryBuilder()
                    .withQuery(QueryBuilders.matchAllQuery())
                    .build();
            elasticsearchRestTemplate.delete(nativeSearchQuery, Blog.class, IndexCoordinates.of("blog"));
        }
    }

本处就不贴出测试的截图了。功能都是测试通过的。

# 查询操作（SearchOperations） #

## 简介 ##

**查询的方法**

Query接口有一个抽象实现和三个实现：

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 2][]

本处我使用NativeSearchQuery。因为它更贴近ES，语法更偏向于ES原来的命令。CriteriaQuery的用法跟JPA的差不多。

**构建Query**

可通过new NativeSearchQueryBuilder()来构建NativeSearchQuery对象NativeSearchQuery中有众多的方法来为我们实现复杂的查询与筛选等操作。其中的build()返回NativeSearchQuery。

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 3][]

**QueryBuilders构造复杂查询条件**

NativeSearchQueryBuilder中接收QueryBuilder

public NativeSearchQueryBuilder withQuery(QueryBuilder queryBuilder) {
    	this.queryBuilder = queryBuilder;
    	return this;
    }

可以用QueryBuilders构造QueryBuilder对象

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 4][]

## 基本查询 ##

通过标题和内容来查找博客。

package com.example.demo.controller;
    
    import com.example.demo.dao.BlogRepository;
    import com.example.demo.entity.Blog;
    import io.swagger.annotations.Api;
    import io.swagger.annotations.ApiOperation;
    import org.apache.commons.lang3.StringUtils;
    import org.elasticsearch.index.query.BoolQueryBuilder;
    import org.elasticsearch.index.query.MatchQueryBuilder;
    import org.elasticsearch.index.query.Operator;
    import org.elasticsearch.index.query.QueryBuilders;
    import org.elasticsearch.search.aggregations.Aggregation;
    import org.elasticsearch.search.aggregations.AggregationBuilder;
    import org.elasticsearch.search.aggregations.AggregationBuilders;
    import org.elasticsearch.search.aggregations.Aggregations;
    import org.elasticsearch.search.aggregations.bucket.terms.ParsedStringTerms;
    import org.elasticsearch.search.aggregations.bucket.terms.Terms;
    import org.elasticsearch.search.aggregations.metrics.ParsedAvg;
    import org.elasticsearch.search.aggregations.metrics.ParsedMax;
    import org.elasticsearch.search.sort.SortBuilder;
    import org.elasticsearch.search.sort.SortBuilders;
    import org.elasticsearch.search.sort.SortOrder;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.data.domain.Page;
    import org.springframework.data.domain.PageImpl;
    import org.springframework.data.domain.PageRequest;
    import org.springframework.data.domain.Range;
    import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
    import org.springframework.data.elasticsearch.core.SearchHit;
    import org.springframework.data.elasticsearch.core.SearchHits;
    import org.springframework.data.elasticsearch.core.query.FetchSourceFilterBuilder;
    import org.springframework.data.elasticsearch.core.query.NativeSearchQuery;
    import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.*;
    import java.util.stream.Collectors;
    
    @Api(tags = "动态查询")
    @RestController
    @RequestMapping("dynamicQuery")
    public class DynamicQueryController {
        @Autowired
        private ElasticsearchRestTemplate elasticsearchRestTemplate;
    
        @ApiOperation("简单查询")
        @GetMapping("simple")
        public List<Blog> simple(String title, String content) {
            NativeSearchQueryBuilder query = new NativeSearchQueryBuilder();
            BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    
            if (StringUtils.isNotBlank(title)) {
                boolQueryBuilder.must(QueryBuilders.matchQuery("title", title));
            }
    
            if (StringUtils.isNotBlank(content)) {
                boolQueryBuilder.must(QueryBuilders.matchQuery("content", content));
            }
    
            query.withQuery(boolQueryBuilder);
            SearchHits<Blog> searchHits = elasticsearchRestTemplate.search(query.build(), Blog.class);
    
            List<Blog> blogs = new ArrayList<>();
            for (SearchHit<Blog> searchHit : searchHits) {
                blogs.add(searchHit.getContent());
            }
            return blogs;
        }
    }

**测试**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 5][]

## 分页排序 ##

通过标题和作者来查找博客，分页，并根据创建时间倒序排序。

@ApiOperation("分页排序")
    @GetMapping("pageAndSort")
    public Page<Blog> pageAndSort(String title, String author) {
    	PageRequest pageRequest = PageRequest.of(0, 2);
    
    	NativeSearchQueryBuilder query = new NativeSearchQueryBuilder();
    	BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    
    	if (StringUtils.isNotBlank(title)) {
    		boolQueryBuilder.must(QueryBuilders.matchQuery("title", title));
    	}
    
    	if (StringUtils.isNotBlank(author)) {
    		boolQueryBuilder.must(QueryBuilders.matchQuery("author", author));
    	}
    
    	query.withQuery(boolQueryBuilder);
    	query.withPageable(pageRequest);
    	query.withSort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC));
    
    	SearchHits<Blog> searchHits = elasticsearchRestTemplate.search(query.build(), Blog.class);
    
    	List<Blog> blogs = new ArrayList<>();
    	for (SearchHit<Blog> searchHit : searchHits) {
    		blogs.add(searchHit.getContent());
    	}
    
    	return new PageImpl<Blog>(blogs, pageRequest, searchHits.getTotalHits());
    }

**测试**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 6][]

## 去重 ##

通过标题和作者来查找博客，根据作者去重。

@ApiOperation("去重")
    @GetMapping("collapse")
    public List<Blog> collapse(String title, String author) {
    	PageRequest pageRequest = PageRequest.of(0, 2);
    
    	NativeSearchQueryBuilder query = new NativeSearchQueryBuilder();
    	BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    
    	if (StringUtils.isNotBlank(title)) {
    		boolQueryBuilder.must(QueryBuilders.matchQuery("title", title));
    	}
    
    	if (StringUtils.isNotBlank(author)) {
    		boolQueryBuilder.must(QueryBuilders.matchQuery("author", author));
    	}
    
    	query.withQuery(boolQueryBuilder);
    	query.withPageable(pageRequest);
    	query.withSort(SortBuilders.fieldSort("createTime").order(SortOrder.DESC));
    
    	// 去重的字段不能是text类型。所以，author的mapping要有keyword，且通过author.keyword去重。
    	query.withCollapseField("author.keyword");
    	//query.withCollapseField("category");
    
    	SearchHits<Blog> searchHits = elasticsearchRestTemplate.search(query.build(), Blog.class);
    
    	List<Blog> blogs = new ArrayList<>();
    	for (SearchHit<Blog> searchHit : searchHits) {
    		blogs.add(searchHit.getContent());
    	}
    
    	return blogs;
    }

**测试**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 7][]

## 聚合 ##

查询标题中带有“java”的每个作者的文章数量。

@ApiOperation("聚合")
    @GetMapping("aggregation")
    public Map<String, Long> aggregation() {
    	NativeSearchQueryBuilder query = new NativeSearchQueryBuilder();
    	BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    
    	boolQueryBuilder.must(QueryBuilders.matchQuery("title", "java"));
    
    	query.withQuery(boolQueryBuilder);
    	// 作为聚合的字段不能是text类型。所以，author的mapping要有keyword，且通过author.keyword聚合。
    	query.addAggregation(AggregationBuilders.terms("per_count").field("author.keyword"));
    	// 不需要获取source结果集，在aggregation里可以获取结果
    	query.withSourceFilter(new FetchSourceFilterBuilder().build());
    
    	SearchHits<Blog> searchHits = elasticsearchRestTemplate.search(query.build(), Blog.class);
    
    	Aggregations aggregations = searchHits.getAggregations();
    	assert aggregations != null;
    	//因为结果为字符串类型 所以用ParsedStringTerms。其他还有ParsedLongTerms、ParsedDoubleTerms等
    	ParsedStringTerms per_count = aggregations.get("per_count");
    	Map<String, Long> map = new HashMap<>();
    	for (Terms.Bucket bucket : per_count.getBuckets()) {
    		map.put(bucket.getKeyAsString(), bucket.getDocCount());
    	}
    
    	return map;
    }

**测试**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 8][]

## 嵌套聚合 ##

查询标题中带有“java”的每个作者的文章数量，再查出各个作者的最新的发文时间。

@ApiOperation("嵌套聚合")
    @GetMapping("subAggregation")
    public Map<String, Map<String, Object>> subAggregation() {
    	NativeSearchQueryBuilder query = new NativeSearchQueryBuilder();
    	BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
    
    	boolQueryBuilder.must(QueryBuilders.matchQuery("title", "java"));
    
    	query.withQuery(boolQueryBuilder);
    	query.addAggregation(AggregationBuilders.terms("per_count").field("author.keyword")
    			.subAggregation(AggregationBuilders.max("latest_create_time").field("createTime"))
    	);
    
    	// 不需要获取source结果集，在aggregation里可以获取结果
    	query.withSourceFilter(new FetchSourceFilterBuilder().build());
    
    	SearchHits<Blog> searchHits = elasticsearchRestTemplate.search(query.build(), Blog.class);
    
    	Aggregations aggregations = searchHits.getAggregations();
    	assert aggregations != null;
    	//因为结果为字符串类型 所以用ParsedStringTerms。其他还有ParsedLongTerms、ParsedDoubleTerms等
    	ParsedStringTerms per_count = aggregations.get("per_count");
    
    	Map<String, Map<String, Object>> map = new HashMap<>();
    
    	for (Terms.Bucket bucket : per_count.getBuckets()) {
    		Map<String, Object> objectMap = new HashMap<>();
    		objectMap.put("docCount", bucket.getDocCount());
    
    		ParsedMax parsedMax = bucket.getAggregations().get("latest_create_time");
    		objectMap.put("latestCreateTime", parsedMax.getValueAsString());
    		map.put(bucket.getKeyAsString(), objectMap);
    	}
    
    	return map;
    }

**测试**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 9][]

# 其他网址 #

[自己挖坑自己填 spring-data-elasticsearch 4.0.0.M4 简单实践\_lixiang19971019的博客-CSDN博客][spring-data-elasticsearch 4.0.0.M4 _lixiang19971019_-CSDN]

[Elasticsearch 整合 Spring Boot（4） - 简书][Elasticsearch _ Spring Boot_4_ -]

[Elasticsearch 聚合搜索报错：mapping 没有keyword 解决\_sweetCandy\_m的博客-CSDN博客][Elasticsearch _mapping _keyword _sweetCandy_m_-CSDN]

[Spring Data Elasticsearch--ElasticsearchRestTemplate--_IT_-CSDN]: https://knife.blog.csdn.net/article/details/120706299
[Elasticsearch Operations]: https://docs.spring.io/spring-data/elasticsearch/docs/current/reference/html/#elasticsearch.operations
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/a5adb5a0e92949eeb5687fa6bd4c4b53.png
[Spring Data Elasticsearch--_--SpringBoot_IT_-CSDN]: https://knife.blog.csdn.net/article/details/120681568
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220828/3775401454ba4d148fa645d33693afa6.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 2]: /images/20220828/f9e817a2f78b48a8b74c62a266e2ede3.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 3]: /images/20220828/710c5baf6b384167a1845c014ae6cec6.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 4]: /images/20220828/5893dda74b7749ebb5f3e8c219acf9a7.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 5]: /images/20220828/2f92a942f1be444088292978e4716a0c.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 6]: /images/20220828/7fc45e2edd01476891cb569ffa90cb1d.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 7]: /images/20220828/a5187a20ca1445caae00b6ba08f70637.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 8]: /images/20220828/5f216cef99cf4928a2f76af04ca2e57e.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBASVTliKnliIPlh7rpnpg_size_20_color_FFFFFF_t_70_g_se_x_16 9]: /images/20220828/1e3df1fea04a41b0a48f3e3b9c6a92eb.png
[spring-data-elasticsearch 4.0.0.M4 _lixiang19971019_-CSDN]: https://blog.csdn.net/lixiang19971019/article/details/105009148
[Elasticsearch _ Spring Boot_4_ -]: https://www.jianshu.com/p/b320ace6db2f
[Elasticsearch _mapping _keyword _sweetCandy_m_-CSDN]: https://blog.csdn.net/sweetCandy_m/article/details/117673029