使用 Openweather API 获取特定日期的天气 - 解析 JSON 响应
Get weather for specific date using Openweather API - parsing JSON response
我正在尝试使用 Android studio 和 Java 构建一个简单的天气预报应用程序。我按照此处的一些说明 (https://www.androdocs.com/java/creating-an-android-weather-app-using-java.html) 起床 运行，这很有效。但是，我只能得到当前的天气。开放天气预报 API 电话似乎持续 5 天。没关系，但是我如何获取用户指定的未来 5 天内的特定日期的天气 - 例如温度和风速？
下面是 JSON 响应示例（已缩短）。即使我可以在中午 12 点提取特定日期前后的信息，并获得该日期的温度和风速，这也足够了。如何解析此 JSON 响应以获取特定日期的温度和风速？非常感谢...抱歉我是初学者...
{"cod":"200","message":0,"cnt":40,"list":[{"dt":1574283600,"main":{"temp":281.75,"temp_min":281.68,"temp_max":281.75,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":93,"temp_kf":0.07},"weather":[{"id":501,"main":"Rain","description":"moderate rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":4.82,"deg":147},"rain":{"3h":5.38},"sys":{"pod":"n"},"dt_txt":"2019-11-20 21:00:00"},{"dt":1574294400,"main":{"temp":281.79,"temp_min":281.74,"temp_max":281.79,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":91,"temp_kf":0.05},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":5.55,"deg":140},"rain":{"3h":1.75},"sys":{"pod":"n"},"dt_txt":"2019-11-21 00:00:00"},{"dt":1574305200,"main":{"temp":279.48,"temp_min":279.44,"temp_max":279.48,"pressure":994,"sea_level":994,"grnd_level":980,"humidity":95,"temp_kf":0.04},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":2.37,"deg":155},"rain":{"3h":0.94},"sys":{"pod":"n"},"dt_txt":"2019-11-21 03:00:00"},{"dt":1574316000,"main":{"temp":278.56,"temp_min":278.54,"temp_max":278.56,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":94,"temp_kf":0.02},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":1.73,"deg":128},"rain":{"3h":0.06},"sys":{"pod":"n"},"dt_txt":"2019-11-21 06:00:00"},{"dt":1574326800,"main":{"temp":279.19,"temp_min":279.19,"temp_max":279.19,"pressure":995,"sea_level":995,"grnd_level":981,"humidity":95,"temp_kf":0},"weather":[{"id":804,"main":"Clouds","description":"overcast clouds","icon":"04d"}],"clouds":{"all":100},"wind":{"speed":1.79,"deg":104},"sys":{"pod":"d"},"dt_txt":"2019-11-21 09:00:00"},{"dt":1574337600,"main":{"temp":282.2,"temp_min":282.2,"temp_max":282.2,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":85,"temp_kf":0},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10d"}],"clouds":{"all":100},"wind":{"speed":2.78,"deg":129},"rain":{"3h":0.19},"sys":{"pod":"d"},"dt_txt":"2019-11-21 12:00:00"}
您可以通过任何一个最流行的 JSON 库（例如 Jackson 或 Gson）将响应 JSON 字符串序列化为 POJO，然后检索您想要的字段日期字段等于给定日期的对象。顺便说一句，您的 JSON 字符串无效，]} 在它的末尾丢失。
POJO
@JsonIgnoreProperties(ignoreUnknown = true)
class Response {
List<Weather> list;
//general getters and setters
}
@JsonIgnoreProperties(ignoreUnknown = true)
class Weather {
JsonNode main;
JsonNode wind;
@JsonProperty("dt_txt")
String dtTxt;
//general getters and setters
}
使用 @JsonIgnoreProperties（由 Jackson 提供）在序列化时忽略那些您不关心的字段。
代码片段
ObjectMapper mapper = new ObjectMapper();
Response response = mapper.readValue(jsonStr, Response.class);
String givenDate = "2019-11-21 12:00:00";
response.getList().forEach(e -> {
if (givenDate.equals(e.getDtTxt())) {
System.out.println("temp: " + e.getMain().get("temp").asText());
System.out.println("wind speed:" + e.getWind().get("speed").asText());
}
});
控制台输出
temp: 282.2
wind speed:2.78
JSON-简单
这是一个使用 JSON-Simple library to parse the JSON data downloaded from OpenWeatherMap.org 的示例应用程序。
package work.basil.example;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class Weather
{
public static void main ( String[] args )
{
Weather app = new Weather();
app.demo();
}
private void demo ( )
{
//Creating a JSONParser object
JSONParser jsonParser = new JSONParser();
try
{
// Download JSON.
String yourKey = "b6907d289e10d714a6e88b30761fae22";
URL url = new URL( "https://samples.openweathermap.org/data/2.5/forecast/hourly?zip=79843&appid=b6907d289e10d714a6e88b30761fae22" + yourKey ); // 79843 = US postal Zip Code for Marfa, Texas.
URLConnection conn = url.openConnection();
BufferedReader reader = new BufferedReader( new InputStreamReader( conn.getInputStream() ) );
// Parse JSON
JSONObject jsonObject = ( JSONObject ) jsonParser.parse( reader );
System.out.println( "jsonObject = " + jsonObject );
JSONArray list = ( JSONArray ) jsonObject.get( "list" );
System.out.println( "list = " + list );
// Loop through each item
for ( Object o : list )
{
JSONObject forecast = ( JSONObject ) o;
Long dt = ( Long ) forecast.get( "dt" ); // Parse text into a number of whole seconds.
Instant instant = Instant.ofEpochSecond( dt ); // Parse the count of whole seconds since 1970-01-01T00:00Z into a `Instant` object, representing a moment in UTC with a resolution of nanoseconds.
ZoneId z = ZoneId.of( "America/Chicago" ); // Specify a time zone using a real `Continent/Region` time zone name. Never use 2-4 letter pseudo-zones such as `PDT`, `CST`, `IST`, etc.
ZonedDateTime zdt = instant.atZone( z ); // Adjust from a moment in UTC to the wall-clock used by the people of a particular region (a time zone). Same moment, same point on the timeline, different wall-clock time.
LocalTime lt = zdt.toLocalTime() ;
// … compare with lt.equals( LocalTime.NOON ) to find the data sample you desire.
System.out.println( "dt : " + dt );
System.out.println( "instant : " + instant );
System.out.println( "zdt : " + zdt );
JSONObject main = ( JSONObject ) forecast.get( "main" );
System.out.println( "main = " + main );
Double temp = ( Double ) main.get( "temp" ); // Better to use BigDecimal instead of Double for accuracy. But I do not know how to get the JSON-Simple library to parse the original string input as a BigDecimal.
System.out.println( "temp = " + temp );
JSONObject wind = ( JSONObject ) forecast.get( "wind" );
System.out.println( "wind = " + wind );
System.out.println( "BASIL - wind.getCLass: " + wind.getClass() );
Double speed = ( Double ) wind.get( "speed" );
System.out.println( "speed = " + speed );
System.out.println( "\n" );
}
}
catch ( FileNotFoundException e )
{
e.printStackTrace();
}
catch ( IOException e )
{
e.printStackTrace();
}
catch ( ParseException e )
{
e.printStackTrace();
}
}
}
小数点分隔符
请注意，当遇到缺少小数分隔符的风速数据点时，此代码会爆炸。例如，为了保持一致性，该数据的发布者应该写 1.0 而不是 1。如果他们这样做了，图书馆就会将 1.0 解析为 Double 而不是将 1 解析为 Long.
JSON-简单 1 现已停用
此代码还使用 JSON 的原始版本 1 - 简单，现已停用。这个项目是分叉的，产生了截然不同的版本 2 和 3。
查看此页面 for details about the parsing-decimal problem and about links to the forked project。
不适合生产使用
因此，虽然我 不推荐将此代码用于生产用途 ，但它可能会对您有所帮助。对于实际工作，请考虑 JSON-Simple 的更高版本 3 或可用于 Java.
的其他几个 JSON-处理库中的任何一个
请参阅 this URL. To make it readable, use your text-editor or IDE 处的示例数据以重新格式化 JSON 数据。
示例输出：
dt : 1553709600
instant : 2019-03-27T18:00:00Z
zdt : 2019-03-27T13:00-05:00[America/Chicago]
main = {"temp":286.44,"temp_min":286.258,"grnd_level":1002.193,"temp_kf":0.18,"humidity":100,"pressure":1015.82,"sea_level":1015.82,"temp_max":286.44}
temp = 286.44
wind = {"deg":202.816,"speed":5.51}
speed = 5.51
dt : 1553713200
instant : 2019-03-27T19:00:00Z
zdt : 2019-03-27T14:00-05:00[America/Chicago]
main = {"temp":286.43,"temp_min":286.3,"grnd_level":1002.667,"temp_kf":0.13,"humidity":100,"pressure":1016.183,"sea_level":1016.183,"temp_max":286.43}
temp = 286.43
wind = {"deg":206.141,"speed":4.84}
speed = 4.84
我正在尝试使用 Android studio 和 Java 构建一个简单的天气预报应用程序。我按照此处的一些说明 (https://www.androdocs.com/java/creating-an-android-weather-app-using-java.html) 起床 运行，这很有效。但是，我只能得到当前的天气。开放天气预报 API 电话似乎持续 5 天。没关系，但是我如何获取用户指定的未来 5 天内的特定日期的天气 - 例如温度和风速？
下面是 JSON 响应示例（已缩短）。即使我可以在中午 12 点提取特定日期前后的信息，并获得该日期的温度和风速，这也足够了。如何解析此 JSON 响应以获取特定日期的温度和风速？非常感谢...抱歉我是初学者...
{"cod":"200","message":0,"cnt":40,"list":[{"dt":1574283600,"main":{"temp":281.75,"temp_min":281.68,"temp_max":281.75,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":93,"temp_kf":0.07},"weather":[{"id":501,"main":"Rain","description":"moderate rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":4.82,"deg":147},"rain":{"3h":5.38},"sys":{"pod":"n"},"dt_txt":"2019-11-20 21:00:00"},{"dt":1574294400,"main":{"temp":281.79,"temp_min":281.74,"temp_max":281.79,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":91,"temp_kf":0.05},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":5.55,"deg":140},"rain":{"3h":1.75},"sys":{"pod":"n"},"dt_txt":"2019-11-21 00:00:00"},{"dt":1574305200,"main":{"temp":279.48,"temp_min":279.44,"temp_max":279.48,"pressure":994,"sea_level":994,"grnd_level":980,"humidity":95,"temp_kf":0.04},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":2.37,"deg":155},"rain":{"3h":0.94},"sys":{"pod":"n"},"dt_txt":"2019-11-21 03:00:00"},{"dt":1574316000,"main":{"temp":278.56,"temp_min":278.54,"temp_max":278.56,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":94,"temp_kf":0.02},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10n"}],"clouds":{"all":100},"wind":{"speed":1.73,"deg":128},"rain":{"3h":0.06},"sys":{"pod":"n"},"dt_txt":"2019-11-21 06:00:00"},{"dt":1574326800,"main":{"temp":279.19,"temp_min":279.19,"temp_max":279.19,"pressure":995,"sea_level":995,"grnd_level":981,"humidity":95,"temp_kf":0},"weather":[{"id":804,"main":"Clouds","description":"overcast clouds","icon":"04d"}],"clouds":{"all":100},"wind":{"speed":1.79,"deg":104},"sys":{"pod":"d"},"dt_txt":"2019-11-21 09:00:00"},{"dt":1574337600,"main":{"temp":282.2,"temp_min":282.2,"temp_max":282.2,"pressure":995,"sea_level":995,"grnd_level":980,"humidity":85,"temp_kf":0},"weather":[{"id":500,"main":"Rain","description":"light rain","icon":"10d"}],"clouds":{"all":100},"wind":{"speed":2.78,"deg":129},"rain":{"3h":0.19},"sys":{"pod":"d"},"dt_txt":"2019-11-21 12:00:00"}
您可以通过任何一个最流行的 JSON 库（例如 Jackson 或 Gson）将响应 JSON 字符串序列化为 POJO，然后检索您想要的字段日期字段等于给定日期的对象。顺便说一句，您的 JSON 字符串无效，]} 在它的末尾丢失。
POJO
@JsonIgnoreProperties(ignoreUnknown = true)
class Response {
List<Weather> list;
//general getters and setters
}
@JsonIgnoreProperties(ignoreUnknown = true)
class Weather {
JsonNode main;
JsonNode wind;
@JsonProperty("dt_txt")
String dtTxt;
//general getters and setters
}
使用 @JsonIgnoreProperties（由 Jackson 提供）在序列化时忽略那些您不关心的字段。
代码片段
ObjectMapper mapper = new ObjectMapper();
Response response = mapper.readValue(jsonStr, Response.class);
String givenDate = "2019-11-21 12:00:00";
response.getList().forEach(e -> {
if (givenDate.equals(e.getDtTxt())) {
System.out.println("temp: " + e.getMain().get("temp").asText());
System.out.println("wind speed:" + e.getWind().get("speed").asText());
}
});
控制台输出
temp: 282.2
wind speed:2.78
JSON-简单
这是一个使用 JSON-Simple library to parse the JSON data downloaded from OpenWeatherMap.org 的示例应用程序。
package work.basil.example;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class Weather
{
public static void main ( String[] args )
{
Weather app = new Weather();
app.demo();
}
private void demo ( )
{
//Creating a JSONParser object
JSONParser jsonParser = new JSONParser();
try
{
// Download JSON.
String yourKey = "b6907d289e10d714a6e88b30761fae22";
URL url = new URL( "https://samples.openweathermap.org/data/2.5/forecast/hourly?zip=79843&appid=b6907d289e10d714a6e88b30761fae22" + yourKey ); // 79843 = US postal Zip Code for Marfa, Texas.
URLConnection conn = url.openConnection();
BufferedReader reader = new BufferedReader( new InputStreamReader( conn.getInputStream() ) );
// Parse JSON
JSONObject jsonObject = ( JSONObject ) jsonParser.parse( reader );
System.out.println( "jsonObject = " + jsonObject );
JSONArray list = ( JSONArray ) jsonObject.get( "list" );
System.out.println( "list = " + list );
// Loop through each item
for ( Object o : list )
{
JSONObject forecast = ( JSONObject ) o;
Long dt = ( Long ) forecast.get( "dt" ); // Parse text into a number of whole seconds.
Instant instant = Instant.ofEpochSecond( dt ); // Parse the count of whole seconds since 1970-01-01T00:00Z into a `Instant` object, representing a moment in UTC with a resolution of nanoseconds.
ZoneId z = ZoneId.of( "America/Chicago" ); // Specify a time zone using a real `Continent/Region` time zone name. Never use 2-4 letter pseudo-zones such as `PDT`, `CST`, `IST`, etc.
ZonedDateTime zdt = instant.atZone( z ); // Adjust from a moment in UTC to the wall-clock used by the people of a particular region (a time zone). Same moment, same point on the timeline, different wall-clock time.
LocalTime lt = zdt.toLocalTime() ;
// … compare with lt.equals( LocalTime.NOON ) to find the data sample you desire.
System.out.println( "dt : " + dt );
System.out.println( "instant : " + instant );
System.out.println( "zdt : " + zdt );
JSONObject main = ( JSONObject ) forecast.get( "main" );
System.out.println( "main = " + main );
Double temp = ( Double ) main.get( "temp" ); // Better to use BigDecimal instead of Double for accuracy. But I do not know how to get the JSON-Simple library to parse the original string input as a BigDecimal.
System.out.println( "temp = " + temp );
JSONObject wind = ( JSONObject ) forecast.get( "wind" );
System.out.println( "wind = " + wind );
System.out.println( "BASIL - wind.getCLass: " + wind.getClass() );
Double speed = ( Double ) wind.get( "speed" );
System.out.println( "speed = " + speed );
System.out.println( "\n" );
}
}
catch ( FileNotFoundException e )
{
e.printStackTrace();
}
catch ( IOException e )
{
e.printStackTrace();
}
catch ( ParseException e )
{
e.printStackTrace();
}
}
}
小数点分隔符
请注意，当遇到缺少小数分隔符的风速数据点时，此代码会爆炸。例如，为了保持一致性，该数据的发布者应该写 1.0 而不是 1。如果他们这样做了，图书馆就会将 1.0 解析为 Double 而不是将 1 解析为 Long.
JSON-简单 1 现已停用
此代码还使用 JSON 的原始版本 1 - 简单，现已停用。这个项目是分叉的，产生了截然不同的版本 2 和 3。
查看此页面
不适合生产使用
因此，虽然我 不推荐将此代码用于生产用途 ，但它可能会对您有所帮助。对于实际工作，请考虑 JSON-Simple 的更高版本 3 或可用于 Java.
的其他几个 JSON-处理库中的任何一个请参阅 this URL. To make it readable, use your text-editor or IDE 处的示例数据以重新格式化 JSON 数据。
示例输出：
dt : 1553709600
instant : 2019-03-27T18:00:00Z
zdt : 2019-03-27T13:00-05:00[America/Chicago]
main = {"temp":286.44,"temp_min":286.258,"grnd_level":1002.193,"temp_kf":0.18,"humidity":100,"pressure":1015.82,"sea_level":1015.82,"temp_max":286.44}
temp = 286.44
wind = {"deg":202.816,"speed":5.51}
speed = 5.51
dt : 1553713200
instant : 2019-03-27T19:00:00Z
zdt : 2019-03-27T14:00-05:00[America/Chicago]
main = {"temp":286.43,"temp_min":286.3,"grnd_level":1002.667,"temp_kf":0.13,"humidity":100,"pressure":1016.183,"sea_level":1016.183,"temp_max":286.43}
temp = 286.43
wind = {"deg":206.141,"speed":4.84}
speed = 4.84