java - 如何从 Map 解析嵌套的 JSON

Question

我正在使用下面的方法将 json 响应映射到 Map

 Map<String, Object> apiResponse = restTemplate.postForObject("https://maps.googleapis.com/maps/api/geocode/json?address="+defaultLocation+"&key="+API_KEY, httpEntity, Map.class, Collections.EMPTY_MAP);

我可以使用下面的代码将整个 JSON 输出到一个字符串

    String jsonResponse = apiResponse.get("results").toString();

然而，我想要得到的是一个嵌套值，它是 results->geometry->location

我尝试了一些使用 JSONArrays、JSONObjects、Substring 的解决方案，但无法让它们工作。

响应 JSON:

{
   "results" : [
      {
         "address_components" : [
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "locality", "political" ]
            },
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "administrative_area_level_2", "political" ]
            },
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "administrative_area_level_1", "political" ]
            },
            {
               "long_name" : "New Zealand",
               "short_name" : "NZ",
               "types" : [ "country", "political" ]
            }
         ],
         "formatted_address" : "Auckland, New Zealand",
         "geometry" : {
            "bounds" : {
               "northeast" : {
                  "lat" : -36.660571,
                  "lng" : 175.287137
               },
               "southwest" : {
                  "lat" : -37.065475,
                  "lng" : 174.4438016
               }
            },
            "location" : {
               "lat" : -36.8484597,
               "lng" : 174.7633315
            },
            "location_type" : "APPROXIMATE",
            "viewport" : {
               "northeast" : {
                  "lat" : -36.660571,
                  "lng" : 175.287137
               },
               "southwest" : {
                  "lat" : -37.065475,
                  "lng" : 174.4438016
               }
            }
         },
         "place_id" : "ChIJ--acWvtHDW0RF5miQ2HvAAU",
         "types" : [ "locality", "political" ]
      },
      {
         "address_components" : [
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "political", "sublocality", "sublocality_level_1" ]
            },
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "locality", "political" ]
            },
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "administrative_area_level_2", "political" ]
            },
            {
               "long_name" : "Auckland",
               "short_name" : "Auckland",
               "types" : [ "administrative_area_level_1", "political" ]
            },
            {
               "long_name" : "New Zealand",
               "short_name" : "NZ",
               "types" : [ "country", "political" ]
            },
            {
               "long_name" : "1010",
               "short_name" : "1010",
               "types" : [ "postal_code" ]
            }
         ],
         "formatted_address" : "Auckland, 1010, New Zealand",
         "geometry" : {
            "bounds" : {
               "northeast" : {
                  "lat" : -36.8364659,
                  "lng" : 174.7838398
               },
               "southwest" : {
                  "lat" : -36.8621041,
                  "lng" : 174.7503805
               }
            },
            "location" : {
               "lat" : -36.8484597,
               "lng" : 174.7633315
            },
            "location_type" : "APPROXIMATE",
            "viewport" : {
               "northeast" : {
                  "lat" : -36.8364659,
                  "lng" : 174.7838398
               },
               "southwest" : {
                  "lat" : -36.8621041,
                  "lng" : 174.7503805
               }
            }
         },
         "place_id" : "ChIJuZqpSPtHDW0R4LOiQ2HvAAU",
         "types" : [ "political", "sublocality", "sublocality_level_1" ]
      }
   ],
   "status" : "OK"
}

如有任何帮助，我们将不胜感激。

Answer 1

JSONObject obj=new JSONObject(jsonresult);
// get result array
JSONArray resultsarray= obj.getJSONArray("results"); 
for (int i=0;i<resultsarray.length(),i++){
        // get Objects using index
        JSONObject jsonobject= results.getJSONObject(i);
        // get geometry object
        JSONObject geometry= jsonobject.getJSONObject("geometry");
        // get location object from geometry
        JSONObject location= geometry.getJSONObject("location");

        // get location values from location object
        double lat = location.optDouble("lat",0.0);
        double long = location.optDouble("lng",0.0);
 }

关于optDouble

public double optDouble(String key, double defaultValue) {

Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.