#37 java: open weather api ex

java/api/build.gradle

@@ -11,6 +11,7 @@ repositories {
 
 dependencies {
     implementation 'org.jsoup:jsoup:1.16.1'
+    implementation 'com.google.code.gson:gson:2.10.1'
 
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'

java/api/src/main/java/openweather/WeatherEx.java

@@ -0,0 +1,57 @@
+package openweather;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class WeatherEx {
+
+    public static void main(String[] args) {
+        final String apiKey = args[0];
+        final String city = "Seoul";
+        final String unit = "metric";
+
+        final StringBuilder sb = new StringBuilder();
+        sb.append("https://api.openweathermap.org/data/2.5/weather");
+        sb.append("?q=").append(city);
+        sb.append("&appid=").append(apiKey);
+        sb.append("&unit=").append(unit);
+
+        try {
+            final URL url = new URL(sb.toString());
+            final HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Accept", "application/json");
+
+            final int responseCode = connection.getResponseCode();
+            if (responseCode == 200) {
+                final BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
+                String inputLine;
+                final StringBuilder content = new StringBuilder();
+
+                while ((inputLine=in.readLine()) != null) {
+                    content.append(inputLine);
+                }
+                in.close();
+
+                System.out.println("content = " + content);
+                JsonObject weatherData = JsonParser.parseString(content.toString()).getAsJsonObject();
+                JsonObject mainData = weatherData.getAsJsonObject("main");
+                double temp = mainData.get("temp").getAsDouble();
+                System.out.println("temp = " + temp);
+
+                connection.disconnect();
+            } else {
+                System.out.println("responseCode = " + responseCode);
+                System.out.println("responseMessage = " + connection.getResponseMessage());
+            }
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}