elasticsearch搜素關鍵字自動補全(suggest)

elasticsearch搜素關鍵字自動補全顧名思義 在搜索框搜索時能有提示列表可供選擇。

最終效果如下：

該搜索優化功能是elasticsearch自帶的即suggest，suggest即存儲一個詞庫，每次搜索發送請求去詞庫中檢索，匹配到即返回。

接下來我們一步一步實現上述功能。

1.建立索引

我這預先準備了一個房屋信息的索引house

{
  "settings": {
    "number_of_replicas": 0
  },
  "mappings": {
    "house": {
      "dynamic": false,
      "properties": {
        "houseId": {
          "type": "long"
        },
        "title": {
          "type": "text",
          "index": "analyzed",
          "analyzer": "ik_smart",
          "search_analyzer": "ik_smart"
        },
        "price": {
          "type": "integer"
        },
        "area": {
          "type": "integer"
        },
        "createTime": {
          "type": "date",
          "format": "strict_date_optional_time||epoch_millis"
        },
        "lastUpdateTime": {
          "type": "date",
          "format": "strict_date_optional_time||epoch_millis"
        },
        "cityEnName": {
          "type": "keyword"
        },
        "regionEnName": {
          "type": "keyword"
        },
        "direction": {
          "type": "integer"
        },
        "distanceToSubway": {
          "type": "integer"
        },
        "subwayLineName": {
          "type": "keyword"
        },
        "subwayStationName": {
          "type": "keyword"
        },
        "tags": {
          "type": "text"
        },
        "street": {
          "type": "keyword"
        },
        "district": {
          "type": "keyword"
        },
        "description": {
          "type": "text",
          "index": "analyzed",
          "analyzer": "ik_smart",
          "search_analyzer": "ik_smart"
        },
        "layoutDesc": {
          "type": "text",
          "index": "analyzed",
          "analyzer": "ik_smart",
          "search_analyzer": "ik_smart"
        },
        "traffic": {
          "type": "text",
          "index": "analyzed",
          "analyzer": "ik_smart",
          "search_analyzer": "ik_smart"
        },
        "roundService": {
          "type": "text",
          "index": "analyzed",
          "analyzer": "ik_smart",
          "search_analyzer": "ik_smart"
        },
        "rentWay": {
          "type": "integer"
        },
        "suggest": {
          "type": "completion"
        },
        "room": {
          "type": "integer"
        }
      }
    }
  }
}

注意關鍵字段suggest，type爲completion

2.向建好的索引中添加數據

主要注意suggest字段中如何添加數據

 private boolean updateSuggest(HouseIndexTemplate indexTemplate) {
        //將分詞字段加入AnalyzeRequestBuilder，通過ik_smart分詞後會生成多個詞組，然後將詞組加入suggest字段
        AnalyzeRequestBuilder requestBuilder = new AnalyzeRequestBuilder(
                this.esClient, AnalyzeAction.INSTANCE, INDEX_NAME, indexTemplate.getTitle(),
                indexTemplate.getLayoutDesc(), indexTemplate.getRoundService(),
                indexTemplate.getDescription(), indexTemplate.getSubwayLineName(),
                indexTemplate.getSubwayStationName());
        //採用ik_smart分詞
        requestBuilder.setAnalyzer("ik_smart");

        AnalyzeResponse response = requestBuilder.get();
        List<AnalyzeResponse.AnalyzeToken> tokens = response.getTokens();
        if (tokens == null) {
            logger.warn("Can not analyze token for house: " + indexTemplate.getHouseId());
            return false;
        }

        List<HouseSuggest> suggests = new ArrayList<>();
        for (AnalyzeResponse.AnalyzeToken token : tokens) {
            // 排序數字類型 & 小於2個字符的分詞結果
            if ("<NUM>".equals(token.getType()) || token.getTerm().length() < 2) {
                continue;
            }

            HouseSuggest suggest = new HouseSuggest();
            suggest.setInput(token.getTerm());
            suggests.add(suggest);
        }

        // 定製化小區自動補全(不需要分詞的字段手動額外加入)
        HouseSuggest suggest = new HouseSuggest();
        suggest.setInput(indexTemplate.getDistrict());
        suggests.add(suggest);

        indexTemplate.setSuggest(suggests);
        return true;
    }

如上代碼表示：

首先將title、layoutDesc、roundService、description、subwayLineName、subwayStationName通過ik_smart分詞後，將分詞後的字詞加入suggests 集合；

然後將不需要分詞的字段district手動加入suggests集合；

其中HouseIndexTemplate 只是一個索引對象，裏面封裝了索引所需字段，注意其中suggest爲 集合：

private List<HouseSuggest> suggest;

最後將HouseIndexTemplate對象寫入elasticsearch中即可。

IndexResponse response = this.esClient.prepareIndex(INDEX_NAME, INDEX_TYPE)
                    .setSource(objectMapper.writeValueAsBytes(indexTemplate), XContentType.JSON).get();

寫入後結構如下 ：

3.開始做檢索

前端js調用檢索接口

 $('#keyword-box').autocomplete({
            minLength: 2, // 最小字符數，默認1
            delay: 300, // 延遲加載300ms
            source: function (request, response) { // 數據源
                $.ajax({
                    url: '/rent/house/autocomplete?prefix=' + request.term,
                    success: function (res) {
                        if (res.code === 200) {
                            response(res.data);
                        }
                    }
                });
            },
            select: function (event, ui) { // 選中事件
                $('#keyword-box').text(ui.item.value);
                window.location.href = locate_url(start, size);
            }
        });

後端接口和服務層：

controller:

    /**
     * 自動補全接口
     */
    @GetMapping("rent/house/autocomplete")
    @ResponseBody
    public ApiResponse autocomplete(@RequestParam(value = "prefix") String prefix) {

        if (prefix.isEmpty()) {
            return ApiResponse.ofStatus(ApiResponse.Status.BAD_REQUEST);
        }
        ServiceResult<List<String>> result = this.searchService.suggest(prefix);
        return ApiResponse.ofSuccess(result.getResult());
    }

service:

@Override
    public ServiceResult<List<String>> suggest(String prefix) {
        CompletionSuggestionBuilder suggestion = SuggestBuilders.completionSuggestion("suggest").prefix(prefix).size(5);

        SuggestBuilder suggestBuilder = new SuggestBuilder();
        suggestBuilder.addSuggestion("autocomplete", suggestion);

        SearchRequestBuilder requestBuilder = this.esClient.prepareSearch(INDEX_NAME)
                .setTypes(INDEX_TYPE)
                .suggest(suggestBuilder);
        logger.debug(requestBuilder.toString());

        SearchResponse response = requestBuilder.get();
        Suggest suggest = response.getSuggest();
        if (suggest == null) {
            return ServiceResult.of(new ArrayList<>());
        }
        Suggest.Suggestion result = suggest.getSuggestion("autocomplete");

        int maxSuggest = 0;
        Set<String> suggestSet = new HashSet<>();

        for (Object term : result.getEntries()) {
            if (term instanceof CompletionSuggestion.Entry) {
                CompletionSuggestion.Entry item = (CompletionSuggestion.Entry) term;

                if (item.getOptions().isEmpty()) {
                    continue;
                }

                for (CompletionSuggestion.Entry.Option option : item.getOptions()) {
                    String tip = option.getText().string();
                    if (suggestSet.contains(tip)) {
                        continue;
                    }
                    suggestSet.add(tip);
                    maxSuggest++;
                }
            }

            if (maxSuggest > 5) {
                break;
            }
        }
        List<String> suggests = Lists.newArrayList(suggestSet.toArray(new String[]{}));
        return ServiceResult.of(suggests);
    }