在 Android 中解析从 MapQuest 返回的 JSON 数据答案

【问题标题】：Parsing JSON Data returned from MapQuest in Android在 Android 中解析从 MapQuest 返回的 JSON 数据
【发布时间】：2015-09-15 13:56:38
【问题描述】：

对 android 和 JSON 的使用完全陌生。我尝试关注以前的一些帖子和答案，但无法使其正常工作。我的结果是这种形式：

{
    "searchResults": [
        {
            "resultNumber": 1,
            "distance": 1.4849,
            "sourceName": "mqap.internationalpois",
            "name": "Le Restaurant",
            "shapePoints": [
                -37.840523,
                144.991425
            ],
            "distanceUnit": "m",
            "key": "97d091ae-1a7e-48c0-b1ab-ea3a26b2da6c",
            "fields": {
                "cats_ext": "(all) Restaurants::French",
                "phone": "+(33)-(4)-68356262",
                "side_of_street": "N",
                "navsics": "581208",
                "lng": 144.991425,
                "city": "Perpignan",
                "country": "FR",
                "cats": "(all) Restaurants",
                "id": "12500223531687",
                "mqap_geography": {
                    "latLng": {
                        "lng": 144.991425,
                        "lat": -37.840523
                    }
                },
                "navsics_ext": "581208::58120849",
                "address": "16 Cours Lazare Escarguel",
                "postal_code": "66000",
                "name": "Le Restaurant",
                "mqap_id": "97d091ae-1a7e-48c0-b1ab-ea3a26b2da6c",
                "disp_lat": -37.840523,
                "street_link_id": "",
                "lat": -37.840523,
                "disp_lng": 144.991425
            }
        },
        {
            "resultNumber": 2,
            "distance": 11.4161,
            "sourceName": "mqap.internationalpois",
            "name": "Le Val d'Or",
            "shapePoints": [
                -37.881779,
                145.167267
            ],
            "distanceUnit": "m",
            "key": "acf9c655-571e-4129-b70f-2e71f64894c2",
            "fields": {
                "cats_ext": "(all) Restaurants::French",
                "phone": "+(33)-(3)-85451370",
                "side_of_street": "N",
                "navsics": "581208",
                "lng": 145.167267,
                "city": "Mercurey",
                "country": "FR",
                "cats": "(all) Restaurants",
                "id": "12500223506348",
                "mqap_geography": {
                    "latLng": {
                        "lng": 145.167267,
                        "lat": -37.881779
                    }
                },
                "navsics_ext": "581208::58120849",
                "address": "140 Grande Rue",
                "postal_code": "71640",
                "name": "Le Val d'Or",
                "mqap_id": "acf9c655-571e-4129-b70f-2e71f64894c2",
                "disp_lat": -37.881779,
                "street_link_id": "",
                "lat": -37.881779,
                "disp_lng": 145.167267
            }
        },
        {
            "resultNumber": 3,
            "distance": 14.9848,
            "sourceName": "mqap.internationalpois",
            "name": "Le Saint Germain",
            "shapePoints": [
                -37.967893,
                145.179022
            ],
            "distanceUnit": "m",
            "key": "66ad361d-e4c2-4e61-bfc3-dda863d84418",
            "fields": {
                "cats_ext": "(all) Restaurants",
                "phone": "+(33)-(4)-67097575",
                "side_of_street": "N",
                "navsics": "581208",
                "lng": 145.179022,
                "city": "Pézenas",
                "country": "FR",
                "cats": "(all) Restaurants",
                "id": "12500223648887",
                "mqap_geography": {
                    "latLng": {
                        "lng": 145.179022,
                        "lat": -37.967893
                    }
                },
                "navsics_ext": "581208",
                "address": "6 Avenue Paul Vidal de La Blache",
                "postal_code": "34120",
                "name": "Le Saint Germain",
                "mqap_id": "66ad361d-e4c2-4e61-bfc3-dda863d84418",
                "disp_lat": -37.967893,
                "street_link_id": "",
                "lat": -37.967893,
                "disp_lng": 145.179022
            }
        }
    ],
    "origin": {
        "latLng": {
            "lng": 144.970242,
            "lat": -37.827057
        },
        "postalCode": "",
        "adminArea5Type": "City",
        "adminArea4": "",
        "adminArea5": "",
        "adminArea4Type": "County",
        "street": "",
        "adminArea1Type": "Country",
        "adminArea1": "",
        "adminArea3": "",
        "adminArea3Type": "State"
    },
    "resultsCount": 3,
    "hostedData": [
        {
            "tableName": "mqap.internationalpois",
            "extraCriteria": "navsics='581208'",
            "parameters": [
                "581208"
            ],
            "columnNames": []
        }
    ],
    "totalPages": 1,
    "info": {
        "statusCode": 0,
        "copyright": {
            "text": "© 2015 MapQuest, Inc.",
            "imageUrl": "http://api.mqcdn.com/res/mqlogo.gif",
            "imageAltText": "© 2015 MapQuest, Inc."
        },
        "messages": []
    },
    "options": {
        "kmlStyleUrl": "http://www.search.mapquestapi.com/kml-default.kml",
        "shapeFormat": "raw",
        "ambiguities": true,
        "pageSize": 3,
        "radius": 25,
        "currentPage": 1,
        "units": "m",
        "maxMatches": 30
    }
}

我正在尝试获取纬度和经度以在地图上显示它们。我尝试创建这样的 JSON 对象以获得第一个位置：

JSONObject mainObject = new JSONObject(resmsg);
JSONObject searchResults =  mainObject.getJSONObject("searchResults");
JSONObject mqap_geography = searchResults.getJSONObject("mqap_geography");
JSONObject latLng = mqap_geography.getJSONObject("latLng");
Double lat = Double.parseDouble(latLng.getJSONObject("lat").toString());
Double lon = Double.parseDouble(latLng.getJSONObject("lng").toString());

任何帮助..

【问题讨论】：

你说你“不能让它工作”是什么意思？有错误吗？返回值是否不正确？请准确无误，否则我们将无法为您提供帮助。
任何帮助.. 是的，学习基础知识...... searchResults 是数组使用正确的JSONObject.getXXXXX() 方法来获取一个数组然后迭代它......至于double，你也有适当的JSONObject.getXXXXX() 方法...关于在 Java 中解析 json 的问题有很多...如果您无法从示例中学习并且需要针对您的特定 JSON 的直接代码，您应该考虑停止编程跨度>

标签： android json google-maps mapquest

【解决方案1】：

使用 Gson。您无需为刚刚发明的轮子重新发明轮胎。

在这里查看他们是如何做到的https://github.com/lissyfeja/MapQuest/blob/master/src/de/bht/mmi/ema/EditEventActivity.java

基本上，您创建一个具有从 JSON 获得的结构的对象，然后告诉 Gson 将您的字符串解析为该对象结构。

mEvent = new Gson().fromJson(json, MQCalendarEvent.class);

这是另一个很好的例子，它直接使用默认解析器解析数据，然后使用 Gson 提供的一些简单方法获取它：Android - Parse JSON using GSON

【讨论】：

【解决方案2】：

searchresult 不是 JSONArray 吗？您的 JSON 代码有点难以阅读

JSONObject mainObject = new JSONObject(resmsg);
JSONArray searchResults =  mainObject.getJSONArray("searchResults");
 ...
 --> Iterate over searchResults to get the JSONObject you need e.g.mqap_geography
....
JSONObject latLng = mqap_geography.getJSONObject("latLng");
Double lat = Double.parseDouble(latLng.getJSONObject("lat").toString());
Double lon = Double.parseDouble(latLng.getJSONObject("lng").toString());

@Edit 肯定没有来自 JSONArray 的方法 .getJSONObject。我没有先编辑这一行的错误

【讨论】：

【解决方案3】：

试试这个：

JSONObject mainObject = new JSONObject(resmsg);
JSONArray searchResults =  mainObject.getJSONArray("searchResults");
for(int i=0 ;i <searchResults.lenth() ; i++)
{
JSONObject searchObject = searchResults.getJSONObject(i);
JSONObject objectField = searchObject.getJSONObject("fields");
JSONObject mqap_geography = objectField.getJSONObject("mqap_geography");
JSONObject latLng = mqap_geography.getJSONObject("latLng");
Double lat = Double.parseDouble(latLng.getString("lat"));
Double lon = Double.parseDouble(latLng.getString("lng"));
}

【讨论】：