SpringBoot integrates ES for CRUD operations

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This article introduces the implementation of ElasticSearch and CRUD operations in Spring Boot, including paging, scrolling, etc. Before I used ES in the company, I had been using packages packaged by predecessors. Recently, I hope to learn ES related technologies from the perspective of native Spring Boot/ES syntax. Hope to help you.

This article is an excerpt from the Spring-boot-examples series, which has been uploaded to github.com/laolunsi/sp…

Install ES and visualization tools

To ES official www.elastic.co/cn/download… For Windows, download the installation package, start the elasticSearch. bat file, and visit http://localhost:9200

In this case, ES is installed. For a better view of your ES data, install the ElasticSearch-Head visualization plugin. Go to github.com/mobz/elasti… Main steps:

• git clone git://github.com/mobz/elasticsearch-head.git
• cd elasticsearch-head
• npm install
• npm run start
• open http://localhost:9100/

http.cors.enabled: true
http.cors.allow-origin: "*"
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Spring Boot introduces ES

Create a spring-boot project that introduces es dependencies:

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
        </dependency>
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The configuration application. Yml:

server:
  port: 8060

spring:
  elasticsearch:
    rest:
      uris: http://localhost:9200

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Create a test object, article:

import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;

import java.util.Date;

@Document(indexName = "article")
public class Article {

    @Id
    private String id;
    private String title;
    private String content;
    private Integer userId;
    private Date createTime;

    // ... igonre getters and setters
}

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Here are three ways to manipulate ES data in Spring Boot:

• Implement ElasticsearchRepository interface
• The introduction of ElasticsearchRestTemplate
• The introduction of ElasticsearchOperations

Implement the corresponding Repository:

import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;

public interface ArticleRepository extends ElasticsearchRepository<Article.String> {}Copy the code

You can now use this ArticleRepository to manipulate Article data in ES. The Article index is not created manually. It is created by default for ElasticSearch.

The following interface realizes spring Boot for ES data insertion, update, paging query, scrolling query, delete and other operations. Can be used as a reference. Among them, use the Repository to capture, save, delete ES data, by using ElasticsearchRestTemplate or ElasticsearchOperations paging/scroll query.

	@Autowired
    private ArticleRepository articleRepository;

    @GetMapping("{id}")
    public JsonResult findById(@PathVariable String id) {
        Optional<Article> article = articleRepository.findById(id);
        JsonResult jsonResult = new JsonResult(true);
        jsonResult.put("article", article.orElse(null));
        return jsonResult;
    }

	@DeleteMapping("{id}")
    public JsonResult delete(@PathVariable String id) {
        // Delete by id
        articleRepository.deleteById(id);
        return new JsonResult(true."Deleted successfully");
    }
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Save the data

	@PostMapping("")
    public JsonResult save(Article article) {
        // Add or update
        String verifyRes = verifySaveForm(article);
        if(! StringUtils.isEmpty(verifyRes)) {return new JsonResult(false, verifyRes);
        }

        if (StringUtils.isEmpty(article.getId())) {
            article.setCreateTime(new Date());
        }

        Article a = articleRepository.save(article);
        booleanres = a.getId() ! =null;
        return new JsonResult(res, res ? "Saved successfully" : "");
    }

    private String verifySaveForm(Article article) {
        if (article == null || StringUtils.isEmpty(article.getTitle())) {
            return "The title cannot be empty.";
        } else if (StringUtils.isEmpty(article.getContent())) {
            return "Content cannot be empty.";
        }

        return null;
    }
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    @Autowired
    private ElasticsearchRestTemplate elasticsearchRestTemplate;

    @Autowired
    ElasticsearchOperations elasticsearchOperations;

    @GetMapping("list")
    public JsonResult list(Integer currentPage, Integer limit) {
        if (currentPage == null || currentPage < 0 || limit == null || limit <= 0) {
            return new JsonResult(false."Please enter valid paging parameters.");
        }
        // paging list query
        // The search method in older versions of Repository is deprecated.
        / / use ElasticSearchRestTemplate or ElasticsearchOperations to paging query here

        JsonResult jsonResult = new JsonResult(true);
        NativeSearchQuery query = new NativeSearchQuery(new BoolQueryBuilder());
        query.setPageable(PageRequest.of(currentPage, limit));

        // Method 1:
        SearchHits<Article> searchHits = elasticsearchRestTemplate.search(query, Article.class);

        // Method 2:
        // SearchHits<Article> searchHits = elasticsearchOperations.search(query, Article.class);

        List<Article> articles = searchHits.getSearchHits().stream().map(SearchHit::getContent).collect(Collectors.toList());
        jsonResult.put("count", searchHits.getTotalHits());
        jsonResult.put("articles", articles);
        return jsonResult;
    }
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Scroll through data

	@GetMapping("scroll")
    public JsonResult scroll(String scrollId, Integer size) {
        // Scroll the Scroll API
        if (size == null || size <= 0) {
            return new JsonResult(false."Please enter number of queries per page");
        }
        NativeSearchQuery query = new NativeSearchQuery(new BoolQueryBuilder());
        query.setPageable(PageRequest.of(0, size));
        SearchHits<Article> searchHits = null;
        if (StringUtils.isEmpty(scrollId)) {
            // Start a scroll query. Set the scroll context to 60 seconds
            // In the same scroll context, you only need to set the query once.
            searchHits = elasticsearchRestTemplate.searchScrollStart(60000, query, Article.class, IndexCoordinates.of("article"));
            if (searchHits instanceofSearchHitsImpl) { scrollId = ((SearchHitsImpl) searchHits).getScrollId(); }}else {
            // Continue scrolling
            searchHits = elasticsearchRestTemplate.searchScrollContinue(scrollId, 60000, Article.class, IndexCoordinates.of("article"));
        }

        List<Article> articles = searchHits.getSearchHits().stream().map(SearchHit::getContent).collect(Collectors.toList());
        if (articles.size() == 0) {
            // End scrolling
            elasticsearchRestTemplate.searchScrollClear(Collections.singletonList(scrollId));
            scrollId = null;
        }

        if (scrollId == null) {
            return new JsonResult(false."At the end of the line");
        } else {
            JsonResult jsonResult = new JsonResult(true);
            jsonResult.put("count", searchHits.getTotalHits());
            jsonResult.put("size", articles.size());
            jsonResult.put("articles", articles);
            jsonResult.put("scrollId", scrollId);
            returnjsonResult; }}Copy the code