Leyendo una respuesta JSON de WeatherUnderground
package test;
import java.net.*;
import java.io.*;
import com.google.gson.*;
import com.google.gson.stream.JsonReader;
public class TestGson {
URL callToApi;
//------------------------------------------------------------------------------
public static void main(String[] args) {
new TestGson();
}
//------------------------------------------------------------------------------
public TestGson(){
try{
sendCallToApi();
readJson();
}catch(IOException e){
e.printStackTrace();
}
}
//------------------------------------------------------------------------------
public void sendCallToApi(){
try{
callToApi = new URL("http://api.wunderground.com/api" +
"/[insert key here]" +
"/geolookup/conditions/forecast/q/" +
"Australia/" +
"Sydney.json");
}catch(MalformedURLException e){
e.printStackTrace();
}
}
//------------------------------------------------------------------------------
public void readJson() throws IOException{
Gson g = new Gson();
InputStreamReader in = new InputStreamReader(callToApi.openStream());
BufferedReader reader = new BufferedReader(in);
String message = "hello";
StringBuffer buf = new StringBuffer();
while(message!=null){
message = reader.readLine();
buf.append(message);
}
message = buf.toString();
String wdf = g.fromJson(message, String.class);
System.out.println(wdf);
}
//------------------------------------------------------------------------------
}
Este es mi primer intento de analizar JSON utilizando GSON. Simplemente estoy haciendo una llamada al sitio Weather Underground pidiéndoles que me envíen el clima de Sydney, Australia.
Sin embargo, me sale varios errores:
Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 2
at com.google.gson.Gson.fromJson(Gson.java:806)
at com.google.gson.Gson.fromJson(Gson.java:761)
at com.google.gson.Gson.fromJson(Gson.java:710)
at com.google.gson.Gson.fromJson(Gson.java:682)
at test.TestGson.readJson(TestGson.java:49)
at test.TestGson.<init>(TestGson.java:19)
at test.TestGson.main(TestGson.java:13)
Caused by: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 2
at com.google.gson.stream.JsonReader.nextString(JsonReader.java:464)
at com.google.gson.internal.bind.TypeAdapters$13.read(TypeAdapters.java:349)
at com.google.gson.internal.bind.TypeAdapters$13.read(TypeAdapters.java:337)
at com.google.gson.Gson.fromJson(Gson.java:795)
... 6 more
¿Qué está causando esos errores? ¿Cómo hago correctamente la llamada a la API Weather Underground para recibir la información del tiempo?
Intenté esto modificando el ejemplo dado en Mykong.com.
Respuesta de JSON de Weather Underground{ "response": { "version": "0.1" ,"termsofService": "http://www.wunderground.com/weather/api/d/terms.html" ,"features": { "geolookup": 1 , "conditions": 1 , "forecast": 1 } } , "location": { "type":"INTLCITY", "country":"SD", "country_iso3166":"SA", "country_name":"Saudi Arabia", "state":"", "city":"Jeddah", "tz_short":"AST", "tz_long":"Asia/Riyadh", "lat":"21.67000008", "lon":"39.15000153", "zip":"00000", "magic":"1", "wmo":"41024", "l":"/q/zmw:00000.1.41024", "requesturl":"global/stations/41024.html", "wuiurl":"http://www.wunderground.com/global/stations/41024.html", "nearby_weather_stations": { "airport": { "station": [ { "city":"Jeddah King Abdul Aziz International Airport", "state":"", "country":"Saudi Arabia", "icao":"OEJN", "lat":"21.70000076", "lon":"39.18333435" }, { "city":"Jeddah", "state":"", "country":"SD", "icao":"OEJN", "lat":"21.67000008", "lon":"39.15000153" }, { "city":"Makkah", "state":"", "country":"SD", "icao":"OEMK", "lat":"21.43000031", "lon":"39.77000046" } ] } , "pws": { "station": [ ] } } } , "current_observation": { "image": { "url":"http://icons-ak.wxug.com/graphics/wu2/logo_130x80.png", "title":"Weather Underground", "link":"http://www.wunderground.com" }, "display_location": { "full":"Jeddah, Saudi Arabia", "city":"Jeddah", "state":"", "state_name":"Saudi Arabia", "country":"SD", "country_iso3166":"SA", "zip":"00000", "latitude":"21.67000008", "longitude":"39.15000153", "elevation":"12.00000000" }, "observation_location": { "full":"Jeddah, ", "city":"Jeddah", "state":"", "country":"SD", "country_iso3166":"SA", "latitude":"21.67000008", "longitude":"39.15000153", "elevation":"39 ft" }, "estimated": { }, "station_id":"OEJN", "observation_time":"Last Updated on February 12, 9:00 AM AST", "observation_time_rfc822":"Tue, 12 Feb 2013 09:00:00 +0300", "observation_epoch":"1360648800", "local_time_rfc822":"Tue, 12 Feb 2013 09:08:53 +0300", "local_epoch":"1360649333", "local_tz_short":"AST", "local_tz_long":"Asia/Riyadh", "local_tz_offset":"+0300", "weather":"Clear", "temperature_string":"77 F (25 C)", "temp_f":77, "temp_c":25, "relative_humidity":"57%", "wind_string":"From the North at 10 MPH", "wind_dir":"North", "wind_degrees":10, "wind_mph":10, "wind_gust_mph":0, "wind_kph":17, "wind_gust_kph":0, "pressure_mb":"1011", "pressure_in":"29.86", "pressure_trend":"0", "dewpoint_string":"61 F (16 C)", "dewpoint_f":61, "dewpoint_c":16, "heat_index_string":"NA", "heat_index_f":"NA", "heat_index_c":"NA", "windchill_string":"NA", "windchill_f":"NA", "windchill_c":"NA", "feelslike_string":"77 F (25 C)", "feelslike_f":"77", "feelslike_c":"25", "visibility_mi":"N/A", "visibility_km":"N/A", "solarradiation":"", "UV":"-1", "precip_1hr_string":"-9999.00 in (-9999.00 mm)", "precip_1hr_in":"-9999.00", "precip_1hr_metric":"-9999.00", "precip_today_string":"0.00 in (0.0 mm)", "precip_today_in":"0.00", "precip_today_metric":"0.0", "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "forecast_url":"http://www.wunderground.com/global/stations/41024.html", "history_url":"http://www.wunderground.com/history/airport/OEJN/2013/2/12/DailyHistory.html", "ob_url":"http://www.wunderground.com/cgi-bin/findweather/getForecast?query=21.67000008,39.15000153" } , "forecast":{ "txt_forecast": { "date":"3:00 AM AST", "forecastday": [ { "period":0, "icon":"partlycloudy", "icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", "title":"Tuesday", "fcttext":"Clear in the morning, then partly cloudy. High of 84F. Breezy. Winds from the NNW at 10 to 20 mph.", "fcttext_metric":"Clear in the morning, then partly cloudy. High of 29C. Breezy. Winds from the NNW at 15 to 30 km/h.", "pop":"0" } , { "period":1, "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "title":"Tuesday Night", "fcttext":"Clear. Low of 70F. Winds from the NNW at 10 to 15 mph.", "fcttext_metric":"Clear. Low of 21C. Breezy. Winds from the NNW at 15 to 25 km/h.", "pop":"0" } , { "period":2, "icon":"partlycloudy", "icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", "title":"Wednesday", "fcttext":"Clear in the morning, then partly cloudy. High of 88F. Winds from the NNW at 5 to 15 mph.", "fcttext_metric":"Clear in the morning, then partly cloudy. High of 31C. Breezy. Winds from the NNW at 10 to 25 km/h.", "pop":"0" } , { "period":3, "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "title":"Wednesday Night", "fcttext":"Clear in the evening, then partly cloudy. Low of 70F. Winds from the NW at 5 to 15 mph.", "fcttext_metric":"Clear in the evening, then partly cloudy. Low of 21C. Breezy. Winds from the NW at 10 to 25 km/h.", "pop":"0" } , { "period":4, "icon":"partlycloudy", "icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", "title":"Thursday", "fcttext":"Clear in the morning, then partly cloudy. High of 88F. Winds from the North at 5 to 10 mph shifting to the WSW in the afternoon.", "fcttext_metric":"Clear in the morning, then partly cloudy. High of 31C. Winds from the North at 5 to 15 km/h shifting to the WSW in the afternoon.", "pop":"0" } , { "period":5, "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "title":"Thursday Night", "fcttext":"Clear. Low of 73F. Winds from the WNW at 5 to 10 mph.", "fcttext_metric":"Clear. Low of 23C. Winds from the WNW at 5 to 15 km/h.", "pop":"0" } , { "period":6, "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "title":"Friday", "fcttext":"Clear. High of 88F. Winds from the NNE at 5 to 10 mph shifting to the WSW in the afternoon.", "fcttext_metric":"Clear. High of 31C. Winds from the NNE at 5 to 20 km/h shifting to the WSW in the afternoon.", "pop":"0" } , { "period":7, "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "title":"Friday Night", "fcttext":"Clear. Low of 72F. Winds from the NW at 5 to 10 mph.", "fcttext_metric":"Clear. Low of 22C. Winds from the NW at 5 to 15 km/h.", "pop":"0" } ] }, "simpleforecast": { "forecastday": [ {"date":{ "epoch":"1360692000", "pretty":"9:00 PM AST on February 12, 2013", "day":12, "month":2, "year":2013, "yday":42, "hour":21, "min":"00", "sec":0, "isdst":"0", "monthname":"February", "weekday_short":"Tue", "weekday":"Tuesday", "ampm":"PM", "tz_short":"AST", "tz_long":"Asia/Riyadh"}, "period":1, "high": { "fahrenheit":"84", "celsius":"29" }, "low": { "fahrenheit":"70", "celsius":"21" }, "conditions":"Partly Cloudy", "icon":"partlycloudy", "icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", "skyicon":"mostlysunny", "pop":0, "qpf_allday": { "in": 0.00, "mm": 0.0 }, "qpf_day": { "in": 0.00, "mm": 0.0 }, "qpf_night": { "in": 0.00, "mm": 0.0 }, "snow_allday": { "in": 0, "cm": 0 }, "snow_day": { "in": 0, "cm": 0 }, "snow_night": { "in": 0, "cm": 0 }, "maxwind": { "mph": 17, "kph": 27, "dir": "NW", "degrees": 317 }, "avewind": { "mph": 14, "kph": 22, "dir": "NW", "degrees": 324 }, "avehumidity": 52, "maxhumidity": 74, "minhumidity": 43 } , {"date":{ "epoch":"1360778400", "pretty":"9:00 PM AST on February 13, 2013", "day":13, "month":2, "year":2013, "yday":43, "hour":21, "min":"00", "sec":0, "isdst":"0", "monthname":"February", "weekday_short":"Wed", "weekday":"Wednesday", "ampm":"PM", "tz_short":"AST", "tz_long":"Asia/Riyadh"}, "period":2, "high": { "fahrenheit":"88", "celsius":"31" }, "low": { "fahrenheit":"70", "celsius":"21" }, "conditions":"Partly Cloudy", "icon":"partlycloudy", "icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", "skyicon":"partlycloudy", "pop":0, "qpf_allday": { "in": 0.00, "mm": 0.0 }, "qpf_day": { "in": 0.00, "mm": 0.0 }, "qpf_night": { "in": 0.00, "mm": 0.0 }, "snow_allday": { "in": 0, "cm": 0 }, "snow_day": { "in": 0, "cm": 0 }, "snow_night": { "in": 0, "cm": 0 }, "maxwind": { "mph": 14, "kph": 22, "dir": "NW", "degrees": 308 }, "avewind": { "mph": 12, "kph": 19, "dir": "NW", "degrees": 315 }, "avehumidity": 51, "maxhumidity": 75, "minhumidity": 39 } , {"date":{ "epoch":"1360864800", "pretty":"9:00 PM AST on February 14, 2013", "day":14, "month":2, "year":2013, "yday":44, "hour":21, "min":"00", "sec":0, "isdst":"0", "monthname":"February", "weekday_short":"Thu", "weekday":"Thursday", "ampm":"PM", "tz_short":"AST", "tz_long":"Asia/Riyadh"}, "period":3, "high": { "fahrenheit":"88", "celsius":"31" }, "low": { "fahrenheit":"73", "celsius":"23" }, "conditions":"Partly Cloudy", "icon":"partlycloudy", "icon_url":"http://icons-ak.wxug.com/i/c/k/partlycloudy.gif", "skyicon":"mostlysunny", "pop":0, "qpf_allday": { "in": 0.00, "mm": 0.0 }, "qpf_day": { "in": 0.00, "mm": 0.0 }, "qpf_night": { "in": 0.00, "mm": 0.0 }, "snow_allday": { "in": 0, "cm": 0 }, "snow_day": { "in": 0, "cm": 0 }, "snow_night": { "in": 0, "cm": 0 }, "maxwind": { "mph": 9, "kph": 14, "dir": "West", "degrees": 259 }, "avewind": { "mph": 7, "kph": 11, "dir": "WSW", "degrees": 250 }, "avehumidity": 51, "maxhumidity": 69, "minhumidity": 37 } , {"date":{ "epoch":"1360951200", "pretty":"9:00 PM AST on February 15, 2013", "day":15, "month":2, "year":2013, "yday":45, "hour":21, "min":"00", "sec":0, "isdst":"0", "monthname":"February", "weekday_short":"Fri", "weekday":"Friday", "ampm":"PM", "tz_short":"AST", "tz_long":"Asia/Riyadh"}, "period":4, "high": { "fahrenheit":"88", "celsius":"31" }, "low": { "fahrenheit":"72", "celsius":"22" }, "conditions":"Clear", "icon":"clear", "icon_url":"http://icons-ak.wxug.com/i/c/k/clear.gif", "skyicon":"mostlysunny", "pop":0, "qpf_allday": { "in": 0.00, "mm": 0.0 }, "qpf_day": { "in": 0.00, "mm": 0.0 }, "qpf_night": { "in": 0.00, "mm": 0.0 }, "snow_allday": { "in": 0, "cm": 0 }, "snow_day": { "in": 0, "cm": 0 }, "snow_night": { "in": 0, "cm": 0 }, "maxwind": { "mph": 10, "kph": 16, "dir": "WSW", "degrees": 248 }, "avewind": { "mph": 7, "kph": 11, "dir": "WSW", "degrees": 248 }, "avehumidity": 53, "maxhumidity": 60, "minhumidity": 38 } ] } }}null