feat: #101 자동완성 구현

src/main/java/com/t3t/bookstoreapi/elastic/controller/AutocompleteController.java

@@ -0,0 +1,24 @@
+package com.t3t.bookstoreapi.elastic.controller;
+
+import com.t3t.bookstoreapi.elastic.service.AutocompleteService;
+import com.t3t.bookstoreapi.model.response.BaseResponse;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.io.IOException;
+import java.util.List;
+
+@RestController
+@RequiredArgsConstructor
+public class AutocompleteController {
+
+    private final AutocompleteService autocompleteService;
+    @GetMapping("/autocomplete")
+    public ResponseEntity<BaseResponse<List<String>>> autocomplete(@RequestParam String prefix) throws IOException {
+        BaseResponse<List<String>> autocomplete = autocompleteService.autocomplete(prefix);
+        return  ResponseEntity.ok().body(autocomplete);
+    }
+}

src/main/java/com/t3t/bookstoreapi/elastic/service/AutocompleteService.java

@@ -0,0 +1,53 @@
+package com.t3t.bookstoreapi.elastic.service;
+
+import com.t3t.bookstoreapi.model.response.BaseResponse;
+import lombok.RequiredArgsConstructor;
+import org.elasticsearch.action.search.SearchRequest;
+import org.elasticsearch.action.search.SearchResponse;
+import org.elasticsearch.client.RequestOptions;
+import org.elasticsearch.client.RestHighLevelClient;
+import org.elasticsearch.search.builder.SearchSourceBuilder;
+import org.elasticsearch.search.suggest.SuggestBuilder;
+import org.elasticsearch.search.suggest.SuggestBuilders;
+import org.elasticsearch.search.suggest.completion.CompletionSuggestionBuilder;
+import org.springframework.stereotype.Service;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.stream.Collectors;
+
+@Service
+@RequiredArgsConstructor
+public class AutocompleteService {
+
+    private final RestHighLevelClient client;
+    public BaseResponse<List<String>> autocomplete(String prefix) throws IOException {
+
+        SearchRequest searchRequest = new SearchRequest("t3t_book"); // Elasticsearch 인덱스 이름
+        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
+
+        CompletionSuggestionBuilder completionSuggestionBuilder =
+                SuggestBuilders.completionSuggestion("book_name.book_name2") // 자동완성 필드 설정
+                        .prefix(prefix)
+                        .size(10);
+
+        searchSourceBuilder.suggest(new SuggestBuilder().addSuggestion("suggest_book_name", completionSuggestionBuilder));
+        searchRequest.source(searchSourceBuilder);
+
+        SearchResponse response = client.search(searchRequest, RequestOptions.DEFAULT);
+        return parseSuggestResponse(response, "suggest_book_name");
+
+    }
+
+
+    private BaseResponse<List<String>> parseSuggestResponse(SearchResponse response, String suggestionName) {
+        List<String> suggestions = response.getSuggest().getSuggestion(suggestionName).getEntries().stream()
+                .flatMap(entry -> entry.getOptions().stream())
+                .map(option -> option.getText().string())
+                .collect(Collectors.toList());
+
+        BaseResponse<List<String>> baseResponse = new BaseResponse<>();
+        baseResponse.setData(suggestions);
+        return baseResponse;
+    }
+}

src/main/java/com/t3t/bookstoreapi/model/response/BaseResponse.java

@@ -4,9 +4,11 @@
 import lombok.Builder;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
+import lombok.Setter;
 
 @JsonInclude(JsonInclude.Include.NON_NULL)
 @Getter
+@Setter
 @NoArgsConstructor
 public class BaseResponse<T> {
     private String message;