通过JSON 5天天气预报获取有关明天天气的数据

Question

Hello :) I am writing a telegram bot that shows todays and tomorrows weather. As data I'm using openweathermap.org.

For now I did getTodaysWeather method that get info about Java Objects from JSON on http://www.jsonschema2pojo.org and wrote this:

public class Weather {

    public static final String URL_SOURCE = "http://api.openweathermap.org/data/2.5/weather?q=";
    public static final String API_KEY = "&APPID=3ad54740fd37f3f14a3a32a09f09cd25";
    public static final String UNITS = "&units=metric";
    public static final String LANG = "&lang=ru";

    public static String getWeather(String message) throws IOException{

        URL url = new URL(URL_SOURCE + message + LANG + UNITS + API_KEY);

        InputStreamReader reader = new InputStreamReader(url.openStream());

        Scanner in = new Scanner((InputStream) url.getContent());
        String result = "";

        while (in.hasNext()) {
            result += in.nextLine();
        }

        OneDayWeather obj = null;
        Gson gson = new Gson();
        String json = result;

        obj = gson.fromJson(json, OneDayWeather.class);

        System.out.println("City " + obj.getName() + "(" + obj.getSys().getCountry()+ ")" + "today's "+ System.lineSeparator() +
                "Temperature: " + obj.getMain().getTemp() + "°C, " + System.lineSeparator()+
                "Humidity: " + obj.getMain().getHumidity() + "%, " + System.lineSeparator()+
                "Rain: " + obj.getWeather().get(0).getDescription()+ System.lineSeparator()+
                "Wind speed: " + obj.getWind().getSpeed() + " m/s";
    }
}

Now I need to write a method that get tomorrow's weather data from this JSON data http://api.openweathermap.org/data/2.5/forecast?q=London&APPID=21f2aefa331b0d3f72e50b14a06ff983 If I think right I need to find the block in data that has date close to "tomorrow 1:00pm" and Get info about temperature, humidity, wind etc. Every block starts with ""dt": 1547672400". I think it means date and time in different format. If it so, I need to find the right block and skip the other.

Unfortunately I don't know how to realise this method. If someone could help me I would be very thankful :)

Answer 1

What you can do is to convert "tomorrow 1:00pm" to a UTC and then to unix timestamp. Store this value as tomorrow13Unix .

Now for each forecast in the list, you compare it to tomorrow13Unix and if it is the same, you have found what you are looking for.

Note that the API splits the times into chunks of three, so you may want to instead look for the largest time that is not greater than tomorrow13Unix .

---

Here is how I would obtain the epoch time for tomorrow at 1pm:

long tomorrow13Unix = java.time.OffsetDateTime.now(java.time.ZoneOffset.UTC).with(java.time.LocalTime.of(13, 0)).plusDays(1).toEpochSecond();

Note

The above will get the current time at UTC, truncate that time to 1pm then add one day. This might not be what you want. You may want to instead use your local time, add one day to it, truncate to 1pm, and convert the resulting time to UTC, in which case you may want to use this instead:

long tomorrow13Unix = java.time.LocalDateTime.now().plusDays(1).with(java.time.LocalTime.of(13, 0)).toEpochSecond(java.time.ZoneOffset.UTC);