java - API 的问题输出为空。仅来自 intellij

Question

我的程序输出为空。我不知道为什么。当我在 Firefox 中输入请求时，一切都很好。

我猜原因可能是在输出代码中的“Array”手镯“[]”中。

public class Connect {

    public String connect() {
        String  output = null;

        try {
            URL url = new URL("http://aviation-edge.com/v2/public/flights?key=[key]=3");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Accept", "application/json");

            if (conn.getResponseCode() != 200) {
                throw new RuntimeException("Failed : HTTP Error code : "
                        + conn.getResponseCode());
            }
            InputStreamReader in = new InputStreamReader(conn.getInputStream());
            BufferedReader br = new BufferedReader(in);
            output = br.readLine();
            System.out.println(output);
            br.close();

        } catch (Exception e) {
            System.out.println("Exception in WeatherApi:- " + e);
        }
        return output;
    }

}

Firefox 的输出 --->

[ { "geography": { "latitude": 42.3101, "longitude": -85.5977, "altitude": 9700.26, "direction": 91.15 }, "speed": { "horizontal": 920.628, "isGround": 0, "vertical": 30.42 }, "departure": { "iataCode": "ORD", "icaoCode": "ORD" }, "arrival": { "iataCode": "YYZ", "icaoCode": "YYZ" }, "aircraft": { "regNumber": "N811UA", "icaoCode": "A319", "icao24": "AB0ED6", "iataCode": "A319" }, "airline": { "iataCode": "UA", "icaoCode": "UAL" }, "flight": { "iataNumber": "UA228", "icaoNumber": "UAL228", "number": "228" }, "system": { "updated": "1558214460", "squawk": "4373" }, "status": "en-route" } ]

请帮帮我，我累了。

Answer 1

我修改了你的程序，检查一下这段代码。现在正在工作。您错过了 while 条件。

public String connect() {
    String output = null;
    String key = "679820-995fb7";

    try {
      String connectUrlString =
          "http://aviation-edge.com/v2/public/flights?key=" + key + "&limit=3";
      System.out.println("URL String : " + connectUrlString);
      //      URL url = new URL("http://aviation-edge.com/v2/public/flights?key=[key]=3");
      URL url = new URL(connectUrlString);
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();
      conn.setRequestMethod("GET");
      conn.setRequestProperty("Accept", "application/json");

      if (conn.getResponseCode() != 200) {
        throw new RuntimeException("Failed : HTTP Error code : " + conn.getResponseCode());
      }

      BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
      String inputLine;
      StringBuffer response = new StringBuffer();

      while ((inputLine = in.readLine()) != null) {
        response.append(inputLine);
      }
      in.close();
      output = response.toString();
    } catch (Exception e) {
      System.out.println("Exception in WeatherApi:- " + e);
    }
    return output;
  }