java - JSON解析返回org.json.JSONException : No value for icon_url

Question

这是我正在做的。

我的 Android 应用程序中有一个 GetWeather 类，其中有一个构造函数，当我实例化如下所示的对象时，我会将当前城市和州传递给该构造函数。

GetWeather weather = new GetWeather(city_send,state_code);

构造函数然后使用所需的城市、州和 API 凭据 ping 一个 API URL，以接收天气数据 json 作为响应。我正在尝试从 json 中读取一个特定值，即 icon_url 从 url 获取内容并显示它。由于代码现在有效，我收到了很好的响应，但是当我尝试从 json 中提取 icon_url 的特定数据时，我收到了一个 logcat 警告 - org.json.JSONException: No value for icon_url

这是我类(class)的代码-

package com.mypackage.android;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

public class GetWeather {

    private static String WEATHER_URL = "http://api.wunderground.com/api/my_api_key/conditions/q/";
    public String weather;
    public String temperature_string;
    public Bitmap weather_icon;

    public GetWeather(String city, String state){

        city = city.replaceAll(" ", "_");
        //construct post URL
        final String GET_WEATHER_URL = WEATHER_URL + state + "/" + city + ".json";  
        new Thread(new Runnable()
        {
            public void run()
            {
                String request = GET_WEATHER_URL;
                HttpResponse rp = null;
                JSONObject jObject = null;
                try {
                    rp = (new DefaultHttpClient()).execute(new HttpPost(request));
                } catch (ClientProtocolException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (rp != null && rp.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
                    Log.i("Get Weather", "Success");
                    HttpEntity entity = rp.getEntity();
                    InputStream is = null;
                    try {
                        is = entity.getContent();
                    } catch (IllegalStateException e2) {
                        e2.printStackTrace();
                    } catch (IOException e2) {
                        e2.printStackTrace();
                    } catch (NullPointerException n1){
                        n1.printStackTrace();
                    }
                    final char[] buffer = new char[0x10000];
                    StringBuilder out = new StringBuilder();
                    Reader in = null;
                    String json_string_response = null;
                    try {
                        in = new InputStreamReader(is, "UTF-8");
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    } catch (NullPointerException n1){
                        n1.printStackTrace();
                    }
                    int read = 0;
                    do {
                        try {
                            read = in.read(buffer, 0, buffer.length);
                        } catch (IOException e) {
                            e.printStackTrace();
                        } catch (NullPointerException n1){
                            n1.printStackTrace();
                        }
                        if (read>0) {
                            out.append(buffer, 0, read);
                        }
                    } while (read>=0);

                    try {
                        is.close();
                        json_string_response = out.toString();
                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }
                    try {
                        jObject = new JSONObject(json_string_response);
                    } catch (JSONException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } 
                    try {
            /*Here is where I try to get the data from the json for specific keys but it says no value found*/          
                        weather = jObject.getString("weather");
                        temperature_string = jObject.getString("temperature_string");
                        String icon_url = jObject.getString("icon_url");        
                        weather_icon = get_weather_icon(icon_url);
                    } catch (JSONException e4) {
                        // TODO Auto-generated catch block
                        e4.printStackTrace();
                    }
                }else{
                        String response = rp.toString().toString();
                        Log.e("Get Weather", response);
                }

            }
        }).start();     
    }

    public static Bitmap get_weather_icon(String url){
        Bitmap bitmap = null;
        InputStream in = null;
        BufferedOutputStream out = null;

        try {

            bitmap = BitmapFactory.decodeStream((InputStream)new URL(url).getContent());

        } catch (MalformedURLException e) {
              e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }

        return bitmap;

    }

}

我从 API 调用中提取并按照上面的代码处理的 jObject 的值如下 - (这是纽约州纽约市的天气数据)

{"response":{"features":{"conditions":1},"termsofService":"http:\/\/www.wunderground.com\/weather\/api\/d\/terms.html","version":"0.1"},"current_observation":{"precip_1hr_metric":" 0","wind_gust_mph":0,"precip_today_metric":"0","pressure_trend":"-","forecast_url":"http:\/\/www.wunderground.com\/US\/NY\/New_York.html","history_url":"http:\/\/www.wunderground.com\/weatherstation\/WXDailyHistory.asp?ID=KNYNEWYO64","estimated":{},"windchill_string":"42 F (6 C)","weather":"Scattered Clouds","station_id":"KNYNEWYO64","UV":"5","wind_gust_kph":0,"observation_epoch":"1364930056","precip_1hr_in":"-999.00","feelslike_string":"42 F (6 C)","observation_time":"Last Updated on April 2, 3:14 PM EDT","temp_f":46.2,"local_tz_long":"America\/New_York","relative_humidity":"29%","temp_c":7.9,"image":{"title":"Weather Underground","url":"http:\/\/icons-ak.wxug.com\/graphics\/wu2\/logo_130x80.png","link":"http:\/\/www.wunderground.com"},"solarradiation":"","visibility_mi":"10.0","observation_location":{"full":"Hells Kitchen, 48th St, NYC, New York, New York","elevation":"66 ft","state":"New York","longitude":"-73.989212","latitude":"40.762157","country_iso3166":"US","country":"US","city":"Hells Kitchen, 48th St, NYC, New York"},"heat_index_c":"NA","wind_mph":7.8,"precip_today_string":"0.00 in (0 mm)","feelslike_f":"42","observation_time_rfc822":"Tue, 02 Apr 2013 15:14:16 -0400","feelslike_c":"6","heat_index_f":"NA","heat_index_string":"NA","ob_url":"http:\/\/www.wunderground.com\/cgi-bin\/findweather\/getForecast?query=40.762157,-73.989212","dewpoint_string":"16 F (-9 C)","local_tz_offset":"-0400","wind_kph":12.6,"windchill_f":"42","windchill_c":"6","pressure_in":"29.96","wind_degrees":202,"dewpoint_c":-9,"pressure_mb":"1015","icon":"partlycloudy","local_time_rfc822":"Tue, 02 Apr 2013 15:24:21 -0400","precip_1hr_string":"-999.00 in ( 0 mm)","icon_url":"http:\/\/icons-ak.wxug.com\/i\/c\/k\/partlycloudy.gif","wind_dir":"SSW","dewpoint_f":16,"display_location":{"zip":"10001","full":"New York, NY","elevation":"17.00000000","state":"NY","longitude":"-73.99700928","latitude":"40.75013351","state_name":"New York","country_iso3166":"US","country":"US","city":"New York"},"visibility_km":"16.1","temperature_string":"46.2 F (7.9 C)","local_tz_short":"EDT","local_epoch":"1364930661","wind_string":"From the SSW at 7.8 MPH","precip_today_in":"0.00"}}

如您所见，我要查找的值在已解析的响应中，为什么我无法获取它或为什么我收到警告未找到值？我做错了什么或者我可以做些什么来从 json 中提取以下值？

"weather":"Scattered Clouds"
"temperature_string":"46.2 F (7.9 C)"
"icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif"

谢谢。

Answer 1

试试这个

JSONObject obj= new JSONObject(json_string_response);
JSONArray array=obj.getJSONArray("response")
 jObject = array.getJSONObject("current_observation");

    weather = jObject.getString("weather");
    temperature_string = jObject.getString("temperature_string");
   String icon_url = jObject.getString("icon_url");