Android App中Google Maps API的JSON解析 [英] JSON parsing of Google Maps API in Android App

问题描述

我正在尝试使用谷歌地图 API 来获取方向时间.我希望创建一个 url，获取 JSON 响应，然后检查该响应的旅行持续时间.创建 JSON 对象后，我无法导航它.对我来说，这表明我在获取响应或导航 JSON 对象时搞砸了.如果您能看一看我从网上教程拼凑起来的零碎代码，我将不胜感激.

I'm trying to use the google maps API to fetch direction times. I'm hoping to create a url, get the JSON response, and then examine that response for travel duration. After I create the JSON object, I have trouble navigating it. To me, this indicates that I have either messed up getting the response or navigating the JSON object. I'd appreciate it if you could peek at the bits and pieces of code I have stitched together from tutorials around the web.

此代码旨在获得响应.它被 try/catch 包围，并且没有触发任何错误.

This code is intended to get the response. It's surrounded by a try/catch and it hasn't triggered any errors.

      String stringUrl = <URL GOES HERE>;

      URL url = new URL(stringUrl);
      HttpURLConnection httpconn = (HttpURLConnection)url.openConnection();
      if (httpconn.getResponseCode() == HttpURLConnection.HTTP_OK)
      {
          BufferedReader input = new BufferedReader(new InputStreamReader(httpconn.getInputStream()),8192);
          String strLine = null;
          while ((strLine = input.readLine()) != null)
          {
              response.append(strLine);
          }
          input.close();
      }
      String jsonOutput = response.toString();

此代码旨在获取该输出并将其解析为最终字符串持续时间，其灵感来自 this stackoverflow answer 用于类似问题.

This code is intended to take that output and parse it into the final string, duration, as inspired by this stackoverflow answer for a similar question.

        JSONObject jsonObject = new JSONObject(jsonOutput);
        JSONObject routeObject = jsonObject.getJSONObject("routes");
        JSONObject legsObject = routeObject.getJSONObject("legs");
        JSONObject durationObject = legsObject.getJSONObject("duration"); 
        String duration = durationObject.getString("text");

我在第二个块的第二行捕捉到一个 JSON 异常.任何人都可以帮助解决这个问题吗?或者提出一种更简单的方法来获取相同的数据?

I'm catching a JSON exception on the second line of the second block. Can anyone help to fix this? Or perhaps suggest a simpler way to get the same data?

感谢这里的第一个有用答案(来自 aromero)，后半部分现在看起来像:

    JSONObject jsonObject = new JSONObject(responseText);
    JSONArray routeObject = jsonObject.getJSONArray("routes");
    JSONArray legsObject = routeObject.getJSONArray(2); ***error***
    JSONObject durationObject = legsObject.getJSONObject(1);
        String duration = durationObject.getString("text");

但它仍然抛出一个 JSON 异常，只是现在它在第三行之后.我敢肯定这很容易解决，但我真的很感激一些帮助.

But it is still throwing a JSON exception, only now it's after the third line. I'm sure this is embarrassingly easy to fix, but I would really appreciate some help.

示例 JSON 文件的相关部分如下所示:

The relevant part of an example JSON file is shown below:

{
   "routes" : [
      {
         "bounds" : {
            "northeast" : {
               "lat" : 34.092810,
               "lng" : -118.328860
            },
            "southwest" : {
               "lat" : 33.995590,
               "lng" : -118.446040
            }
         },
         "copyrights" : "Map data ©2011 Google",
         "legs" : [
            {
               "distance" : {
                  "text" : "12.9 mi",
                  "value" : 20807
               },
               "duration" : {
                  "text" : "27 mins",
                  "value" : 1619
               },

推荐答案

"routes" 是一个数组，使用 getJSONObject 代替 getJSONArray

"routes" is an array, instead of using getJSONObject, use getJSONArray

legs"也是一个数组.

"legs" is an array also.

JSONObject jsonObject = new JSONObject(responseText);

// routesArray contains ALL routes
JSONArray routesArray = jsonObject.getJSONArray("routes");
// Grab the first route
JSONObject route = routesArray.getJSONObject(0);
// Take all legs from the route
JSONArray legs = route.getJSONArray("legs");
// Grab first leg
JSONObject leg = legs.getJSONObject(0);

JSONObject durationObject = leg.getJSONObject("duration");
String duration = durationObject.getString("text");

这篇关于Android App中Google Maps API的JSON解析的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！