我正在制作一个天气应用程序，以了解如何在Java中使用Gson和Web api，这是我当前的代码：
public class Weather
{
public static void main(String[] args) throws Exception
{
URL ipStacks = new URL("http://api.ipstack.com/check?access_key=(my api key)");
BufferedReader reader = new BufferedReader(
new InputStreamReader(ipStacks.openStream()));
String inputLine = reader.readLine();
String json = inputLine;
Gson gson = new Gson();
LocationData location = gson.fromJson(json, LocationData.class);
System.out.println(location.ip);
System.out.println(location.latitude);
System.out.println(location.longitude);
String darkSkyBase = "https://api.darksky.net/forecast/(my api key)/";
URL darkSky = new URL(darkSkyBase+location.latitude+","+location.longitude);
BufferedReader reader2 = new BufferedReader(
new InputStreamReader(darkSky.openStream()));
inputLine = reader2.readLine();
WeatherData weather = gson.fromJson(inputLine, WeatherData.class);
System.out.println(weather.currently);
}
}
class LocationData
{
String ip;
String latitude;
String longitude;
}
class WeatherData
{
String currently;
}
我收到此错误：
Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 81 path $.currently
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:226)
at com.google.gson.Gson.fromJson(Gson.java:927)
at com.google.gson.Gson.fromJson(Gson.java:892)
at com.google.gson.Gson.fromJson(Gson.java:841)
at com.google.gson.Gson.fromJson(Gson.java:813)
at com.thomasbriggs.json.App.main(App.java:37)
Caused by: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 81 path $.currently
at com.google.gson.stream.JsonReader.nextString(JsonReader.java:825)
at com.google.gson.internal.bind.TypeAdapters$16.read(TypeAdapters.java:402)
at com.google.gson.internal.bind.TypeAdapters$16.read(TypeAdapters.java:390)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
... 5 more
我正在猜测，因为使用darksky api，当前是另一个json列表，但是我如何告诉Gson期望一个json列表？
我遇到麻烦的JSON字符串如下所示：
{
"latitude": 42.3601,
"longitude": -71.0589,
"timezone": "America/New_York",
"currently": {
"time": 1509993277,
"summary": "Drizzle",
"icon": "rain",
"nearestStormDistance": 0,
"precipIntensity": 0.0089,
"precipIntensityError": 0.0046,
"precipProbability": 0.9,
"precipType": "rain",
"temperature": 66.1,
"apparentTemperature": 66.31,
"dewPoint": 60.77,
"humidity": 0.83,
"pressure": 1010.34,
"windSpeed": 5.59,
"windGust": 12.03,
"windBearing": 246,
"cloudCover": 0.7,
"uvIndex": 1,
"visibility": 9.84,
"ozone": 267.44
},
"minutely": {
"summary": "Light rain stopping in 13 min., starting again 30 min. later.",
"icon": "rain",
"data": [{
"time": 1509993240,
"precipIntensity": 0.007,
"precipIntensityError": 0.004,
"precipProbability": 0.84,
"precipType": "rain"
},
...
]
},
"hourly": {
"summary": "Rain starting later this afternoon, continuing until this evening.",
"icon": "rain",
"data": [{
"time": 1509991200,
"summary": "Mostly Cloudy",
"icon": "partly-cloudy-day",
"precipIntensity": 0.0007,
"precipProbability": 0.1,
"precipType": "rain",
"temperature": 65.76,
"apparentTemperature": 66.01,
"dewPoint": 60.99,
"humidity": 0.85,
"pressure": 1010.57,
"windSpeed": 4.23,
"windGust": 9.52,
"windBearing": 230,
"cloudCover": 0.62,
"uvIndex": 1,
"visibility": 9.32,
"ozone": 268.95
},
...
]
},
"daily": {
"summary": "Mixed precipitation throughout the week, with temperatures falling to 39°F on Saturday.",
"icon": "rain",
"data": [{
"time": 1509944400,
"summary": "Rain starting in the afternoon, continuing until evening.",
"icon": "rain",
"sunriseTime": 1509967519,
"sunsetTime": 1510003982,
"moonPhase": 0.59,
"precipIntensity": 0.0088,
"precipIntensityMax": 0.0725,
"precipIntensityMaxTime": 1510002000,
"precipProbability": 0.73,
"precipType": "rain",
"temperatureHigh": 66.35,
"temperatureHighTime": 1509994800,
"temperatureLow": 41.28,
"temperatureLowTime": 1510056000,
"apparentTemperatureHigh": 66.53,
"apparentTemperatureHighTime": 1509994800,
"apparentTemperatureLow": 35.74,
"apparentTemperatureLowTime": 1510056000,
"dewPoint": 57.66,
"humidity": 0.86,
"pressure": 1012.93,
"windSpeed": 3.22,
"windGust": 26.32,
"windGustTime": 1510023600,
"windBearing": 270,
"cloudCover": 0.8,
"uvIndex": 2,
"uvIndexTime": 1509987600,
"visibility": 10,
"ozone": 269.45,
"temperatureMin": 52.08,
"temperatureMinTime": 1510027200,
"temperatureMax": 66.35,
"temperatureMaxTime": 1509994800,
"apparentTemperatureMin": 52.08,
"apparentTemperatureMinTime": 1510027200,
"apparentTemperatureMax": 66.53,
"apparentTemperatureMaxTime": 1509994800
},
...
]
},
"alerts": [
{
"title": "Flood Watch for Mason, WA",
"time": 1509993360,
"expires": 1510036680,
"description": "...FLOOD WATCH REMAINS IN EFFECT THROUGH LATE MONDAY NIGHT...\nTHE FLOOD WATCH CONTINUES FOR\n* A PORTION OF NORTHWEST WASHINGTON...INCLUDING THE FOLLOWING\nCOUNTY...MASON.\n* THROUGH LATE FRIDAY NIGHT\n* A STRONG WARM FRONT WILL BRING HEAVY RAIN TO THE OLYMPICS\nTONIGHT THROUGH THURSDAY NIGHT. THE HEAVY RAIN WILL PUSH THE\nSKOKOMISH RIVER ABOVE FLOOD STAGE TODAY...AND MAJOR FLOODING IS\nPOSSIBLE.\n* A FLOOD WARNING IS IN EFFECT FOR THE SKOKOMISH RIVER. THE FLOOD\nWATCH REMAINS IN EFFECT FOR MASON COUNTY FOR THE POSSIBILITY OF\nAREAL FLOODING ASSOCIATED WITH A MAJOR FLOOD.\n",
"uri": "http://alerts.weather.gov/cap/wwacapget.php?x=WA1255E4DB8494.FloodWatch.1255E4DCE35CWA.SEWFFASEW.38e78ec64613478bb70fc6ed9c87f6e6"
},
...
],
{
"flags": {
"units": "us",
...
}
}
如果您有任何疑问，请帮忙。
答案 0 :(得分：0)
我正在检查JSON，看来您正在获得经度和纬度的双精度值：
"latitude": 42.3601,
"longitude": -71.0589,
但是您正在尝试将它们保存在字符串中
class LocationData
{
String ip;
String latitude;
String longitude;
}
将变量更改为两倍，然后重试。
答案 1 :(得分：0)
currently是一个对象，而您的类型是String。如果您不想为currently创建结构，则将其声明为地图Map<String, Object> currently-GSON会将所有键值对放在此处