URL からの JSON の解析に問題があります。以下、コードです。
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.List;
import com.google.gson.Gson;
public class Test_Application {
/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
Gson gson = new Gson();
String json = readUrl("http://api.wunderground.com/api/57dd9039b81a9c21/conditions/q/CA/San_Francisco.json");
Page page = gson.fromJson(json, Page.class);
System.out.println(page.description);
System.out.println(page.language);
System.out.println(page.link);
System.out.println(page.title);
}
private static String readUrl(String urlString) throws Exception {
BufferedReader reader = null;
try {
URL url = new URL(urlString);
reader = new BufferedReader(new InputStreamReader(url.openStream()));
StringBuffer buffer = new StringBuffer();
int read;
char[] chars = new char[1024];
while ((read = reader.read(chars)) != -1)
buffer.append(chars, 0, read);
return buffer.toString();
} finally {
if (reader != null)
reader.close();
}
}
static class Page {
String title;
String link;
String description;
String language;
List<Item> items;
}
static class Item {
String title;
String link;
String description;
}
}
出力は次のとおりです。
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null
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問題は、データを読み取るのに不適切なクラスがあることです。それは正しいでしょうか？
ありがとう
編集
Web サイトは以下を返します。
{
"response": {
"version": "0.1",
"termsofService": "http://www.wunderground.com/weather/api/d/terms.html",
"features": {
"conditions": 1
}
},
"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": "San Francisco, CA",
"city": "San Francisco",
"state": "CA",
"state_name": "California",
"country": "US",
"country_iso3166": "US",
"zip": "94101",
"latitude": "37.77500916",
"longitude": "-122.41825867",
"elevation": "47.00000000"
},
"observation_location": {
"full": "SOMA - Near Van Ness, San Francisco, California",
"city": "SOMA - Near Van Ness, San Francisco",
"state": "California",
"country": "US",
"country_iso3166": "US",
"latitude": "37.773285",
"longitude": "-122.417725",
"elevation": "49 ft"
},
"estimated": {
},
"station_id": "KCASANFR58",
"observation_time": "Last Updated on February 19, 7:08 AM PST",
"observation_time_rfc822": "Tue, 19 Feb 2013 07:08:18 -0800",
"observation_epoch": "1361286498",
"local_time_rfc822": "Tue, 19 Feb 2013 07:08:31 -0800",
"local_epoch": "1361286511",
"local_tz_short": "PST",
"local_tz_long": "America/Los_Angeles",
"local_tz_offset": "-0800",
"weather": "Mostly Cloudy",
"temperature_string": "47.9 F (8.8 C)",
"temp_f": 47.9,
"temp_c": 8.8,
"relative_humidity": "87%",
"wind_string": "From the SW at 4.0 MPH Gusting to 13.0 MPH",
"wind_dir": "SW",
"wind_degrees": 225,
"wind_mph": 4.0,
"wind_gust_mph": "13.0",
"wind_kph": 6.4,
"wind_gust_kph": "20.9",
"pressure_mb": "1012",
"pressure_in": "29.90",
"pressure_trend": "-",
"dewpoint_string": "44 F (7 C)",
"dewpoint_f": 44,
"dewpoint_c": 7,
"heat_index_string": "NA",
"heat_index_f": "NA",
"heat_index_c": "NA",
"windchill_string": "46 F (8 C)",
"windchill_f": "46",
"windchill_c": "8",
"feelslike_string": "46 F (8 C)",
"feelslike_f": "46",
"feelslike_c": "8",
"visibility_mi": "10.0",
"visibility_km": "16.1",
"solarradiation": "",
"UV": "0",
"precip_1hr_string": "0.00 in ( 0 mm)",
"precip_1hr_in": "0.00",
"precip_1hr_metric": " 0",
"precip_today_string": "0.02 in (1 mm)",
"precip_today_in": "0.02",
"precip_today_metric": "1",
"icon": "mostlycloudy",
"icon_url": "http://icons-ak.wxug.com/i/c/k/mostlycloudy.gif",
"forecast_url": "http://www.wunderground.com/US/CA/San_Francisco.html",
"history_url": "http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KCASANFR58",
"ob_url": "http://www.wunderground.com/cgi-bin/findweather/getForecast?query=37.773285,-122.417725"
}
}
更新されたコード
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.List;
import com.google.gson.Gson;
public class Test_Application {
/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
Gson gson = new Gson();
String json = readUrl("http://api.wunderground.com/api/57dd9039b81a9c21/conditions/q/CA/San_Francisco.json");
// Page page = gson.fromJson(json, Page.class);
Response response = gson.fromJson(json, Response.class);
System.out.println(response.termsOfService);
System.out.println(response.version);
}
private static String readUrl(String urlString) throws Exception {
BufferedReader reader = null;
try {
URL url = new URL(urlString);
reader = new BufferedReader(new InputStreamReader(url.openStream()));
StringBuffer buffer = new StringBuffer();
int read;
char[] chars = new char[1024];
while ((read = reader.read(chars)) != -1)
buffer.append(chars, 0, read);
return buffer.toString();
} finally {
if (reader != null)
reader.close();
}
}
static class Response{
String version;
String termsOfService;
}
}