基于Spring Boot+Elasticsearch实现类谷歌搜索引擎，需按_source字段搜索

Hey there! Let's get that _source-based search up and running for your Spring Boot + Elasticsearch search engine. Since you already have the index set up via Logstash and can fetch records by ID, here's a straightforward implementation tailored to your setup:

First, create an entity class that maps directly to the _source fields in your bookdata index. This lets Spring Data Elasticsearch handle serialization/deserialization of search results seamlessly:

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

// For Elasticsearch 7.x+, remove the `type` parameter (it's deprecated)
@Document(indexName = "bookdata", type = "books")
public class Book {
    @Id
    private String id;
    private String title;
    private String author;
    private String description;
    // Add other fields that match your _source structure
    // Include getters and setters for all fields
}

Next, create a service class to construct and execute Elasticsearch queries. We'll use a multi-match query here to search across multiple fields in the _source (adjust the field names to match your actual data):

import org.elasticsearch.index.query.QueryBuilders;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import org.springframework.data.elasticsearch.core.SearchHits;
import org.springframework.data.elasticsearch.core.query.NativeSearchQuery;
import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
import org.springframework.stereotype.Service;

@Service
public class BookSearchService {

    private final String INDEX = "bookdata";
    private final String TYPE = "books"; // Remove this for ES 7.x+

    private final ElasticsearchRestTemplate elasticsearchRestTemplate;

    // Constructor injection (preferred over @Autowired)
    public BookSearchService(ElasticsearchRestTemplate elasticsearchRestTemplate) {
        this.elasticsearchRestTemplate = elasticsearchRestTemplate;
    }

    public SearchHits<Book> searchBooksByKeyword(String keyword) {
        // Build a multi-match query to search across title, author, and description
        NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
                .withIndices(INDEX)
                .withTypes(TYPE) // Remove this line for ES 7.x+
                .withQuery(QueryBuilders.multiMatchQuery(keyword, "title", "author", "description")
                        .fuzziness("AUTO") // Handle minor spelling errors
                        .prefixLength(2)) // Optimize performance for prefix matches
                .build();

        return elasticsearchRestTemplate.search(searchQuery, Book.class);
    }
}

Expose an endpoint so your search component can send requests and receive results:

import org.springframework.data.elasticsearch.core.SearchHits;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class BookSearchController {

    private final BookSearchService bookSearchService;

    public BookSearchController(BookSearchService bookSearchService) {
        this.bookSearchService = bookSearchService;
    }

    @GetMapping("/search")
    public SearchHits<Book> searchBooks(@RequestParam String keyword) {
        return bookSearchService.searchBooksByKeyword(keyword);
    }
}

• Highlight Matching Text: Show users exactly where their keyword appears by adding highlighting to the query. Modify the service method like this:

  NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
          .withIndices(INDEX)
          .withTypes(TYPE)
          .withQuery(QueryBuilders.multiMatchQuery(keyword, "title", "author", "description"))
          .withHighlightFields(
                  new HighlightBuilder.Field("title").preTags("<strong>").postTags("</strong>"),
                  new HighlightBuilder.Field("description").preTags("<strong>").postTags("</strong>")
          )
          .build();
  

  You can retrieve the highlighted content from SearchHit objects later to display in your frontend.

• Precise Phrase Matching: If you want to match exact phrases instead of individual words, use QueryBuilders.matchPhraseQuery("title", keyword) instead of the multi-match query.

内容的提问来源于stack exchange，提问作者Karthikeyan