Question

我正在Spring Boot 2中创建一个端点，并使用Spring webflux。在此端点中，我将从呼叫者处获取纬度和经度，并将基于此返回状态。为了获取状态，我正在调用弹性搜索API来获取数据。

我能够从Elastic搜索API中获得如下响应：

{
  "took": 11,
  "timed_out": false,
  "_shards": {
    "total": 1,
    "successful": 1,
    "failed": 0
  },
  "hits": {
    "total": 117252,
    "max_score": null,
    "hits": [
      {
        "_index": "geolocation",
        "_type": "geolocationdata",
        "_id": "AWt0m6GJqkN7DgSP9Lsd",
        "_score": null,
        "_source": {
          "network": "117.254.200.0/22",
          "geonameId": 1262062,
          "registeredCountrygeonameId": 1269750,
          "representedCountrygeonameId": "",
          "postalCode": "370655",
          "location": "23.2667,68.8333",
          "accuracyRadius": 100,
          "localecode": "en",
          "continentcode": "AS",
          "continentname": "Asia",
          "countryisocode": "IN",
          "countryname": "India",
          "subdivision1isocode": "GJ",
          "subdivision1nname": "Gujarat",
          "subdivision2isocode": "",
          "subdivision2nname": "",
          "cityName": "Naliya",
          "metroCode": "",
          "timeZone": "Asia/Kolkata"
        },
        "sort": [
          6986.775031169917
        ]
      }
    ]
  }
}

一旦有了此JSON，我想仅从其中获取必要的字段，并构建一个API所需的模型，该模型将返回给调用者。

这是我如何使用Elastic search API并获取结果

private WebClient webClient;

@PostConstruct
public void init() {
    this.webClient = WebClient.builder()
        .baseUrl("http://172.24.5.162:9200/geolocation")
        .defaultHeader(
            HttpHeaders.CONTENT_TYPE, 
            MediaType.APPLICATION_JSON_VALUE)
        .build();
}

public String getGeoname(String latitude, String longitude) throws Exception {
    try {
        String req = "{\"from\": 0,\"size\": 1,\"sort\": {\"_geo_distance\": {\"location\": {\"lat\": " + latitude
                + ",\"lon\": " + longitude
                + "},\"order\": \"asc\",\"unit\": \"km\",\"distance_type\": \"plane\"}}}";

        final String test;

        //result from Elastic search API
        Mono<String> result = webClient.post()
                                 .uri("/_search")
                                 .body(Mono.just(req), String.class)
                                 .retrieve().bodyToMono(String.class);

    } catch (Exception ex) {
        log.error("Exception while sending request to Elastic search Lat: " + latitude + " Long: " + longitude, ex);
        return gson.toJson(new ErrorModel(ErrorCodes.BAD_INPUT, "Bad Input"));
    }
    return "";
}

在结果变量中，我具有上面显示为Mono的JSON。如果我将对结果变量使用block（）方法来获取JSON IWant字符串，则它将阻塞主线程并变为阻塞状态。我的需求是消耗此Mono，以便可以进行以下操作（基本上是在构建我的模型的GeoLocation）

String hits = "";
JSONObject jsonObject = new JSONObject(o);

if (jsonObject.has("hits") && jsonObject.getJSONObject("hits").has("hits")) {
    hits = jsonObject.getJSONObject("hits")
        .getString("hits");

    hits = hits.substring(1);

    JSONObject hitsJson = new JSONObject(hits);
    JSONObject source = new JSONObject();
    if (hitsJson.has("_source")) {
        source = hitsJson.getJSONObject("_source");
        GeoLocation geolocation = new GeoLocation(source.getString("continentname"),
        source.getString("countryname"), 
        source.getString("subdivision1nname"),
        source.getString("cityName"));

        geoLocationResponse = Mono.just(gson.toJson(geolocation));

如何以非阻塞方式进行上述操作并将结果返回给端点调用者？我正在考虑从我的RestController返回Mono。

Answer 1

首先，您不要在反应式环境中使用try catch，我们创建Mono.error，然后在信号链中稍后对这些错误采取行动。

您应该真正查看一些教程或尝试一下反应堆项目文档中的基本入门。它将对您有很大帮助。

您应该利用Spring Boot中捆绑的jackson，而不要使用JSONObject和Gson。

public Mono<GeoLocation> getGeoname(String latitude, String longitude) {
    final String req = "{\"from\": 0,\"size\": 1,\"sort\": {\"_geo_distance\": {\"location\": {\"lat\": " + latitude
                + ",\"lon\": " + longitude
                + "},\"order\": \"asc\",\"unit\": \"km\",\"distance_type\": \"plane\"}}}";

    return webClient.post()
            .uri("/_search")
            .body(Mono.just(req), String.class)
            .exchange()
            .flatMap(clientResponse -> {
                // Check status if not 200 create a mono error that we will act upon later
                if(clientResponse.rawStatusCode() != 200)
                    return Mono.error(RuntimeException::new);
                return clientResponse.bodyToMono(String.class);
            }).map(body -> {

                // if you want to work with strings then do your mapping here
                // otherwise replace bodyToMono(FooBar.class) the FooBar class with a              
                // representation of the returned body and jackson will map to it.

                return new GeoLocation();
            }).doOnError(throwable -> {
                // handle the mono error we created earlier here, and throw an exception.
                // Then handle the exception later in a global exception handler
                throw new RuntimeException(throwable);
            });
}

我正在尝试使用Spring webflux消耗弹性搜索API以使我的API端点不受阻塞

1 个答案: