將請求發送到Java中的Google Elevation API

Question

我正在嘗試將Post請求發送到Google海拔API並期待響應

private final String ELEVATION_API_URL =  "https://maps.googleapis.com/maps/api/elevation/json";

private final String USER_AGENT = "Mozilla/5.0";

String urlParameters = "locations=6.9366681,79.9393521&sensor=true&key=<API KEY>";


URL obj = new URL(ELEVATION_API_URL);
            java.net.HttpURLConnection con = (java.net.HttpURLConnection)obj.openConnection();

            //add reuqest header
            con.setRequestMethod("POST");
            con.setRequestProperty("User-Agent", USER_AGENT);
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            con.setRequestProperty("Content-Language", "en-US");  

            String urlParameters = request;

            // Send post request
            con.setDoOutput(true);
            DataOutputStream wr = new DataOutputStream(con.getOutputStream());
            wr.writeBytes(urlParameters);
            wr.flush();
            wr.close();

            int responseCode = con.getResponseCode();

我正在以這種方式發送請求，但得到的響應代碼為400。當從瀏覽器發送請求時，此代碼有效。 此代碼有什么問題。

Answer 1

為了讓我取回XML，我對您的項目進行了以下更改

StringBuilder response = new StringBuilder(); // placed on the top of your Class

**wr.writeBytes(urlParameters.toString());** // as you have it in your code
System.out.println("ResponseMessage : " + connection.getResponseMessage());
System.out.println("RequestMethod : " + connection.getRequestMethod());

in = new BufferedReader(new InputStreamReader(connection.getInputStream()));

String inputLine;

while ((inputLine = in.readLine()) != null) {

    response.append(inputLine);

}

in.close();

wr.flush();

wr.close();

//我將網址更改為：
私有的最終字符串ELEVATION_API_URL =“ https://maps.googleapis.com/maps/api/elevation/xml ”;

//**I get XML in the response** 

return response.toString();

Answer 2

我認為url參數有問題。

首先，因為發送空的海拔api請求確實會返回代碼400（ Invalid request. Missing the 'path' or 'locations' parameter. ）。

其次，因為這有效（返回200）：

public void test() throws Exception {
    String ELEVATION_API_URL =  "https://maps.googleapis.com/maps/api/elevation/json";

    String USER_AGENT = "Mozilla/5.0";

    String urlParameters = "locations=6.9366681,79.9393521&sensor=true";


    URL obj = new URL(ELEVATION_API_URL + "?" + urlParameters);
    HttpURLConnection con = (HttpURLConnection) obj.openConnection();

    //add reuqest header
    con.setRequestMethod("POST");
    con.setRequestProperty("User-Agent", USER_AGENT);
    con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    con.setRequestProperty("Content-Language", "en-US");

    //String urlParameters = request;

    // Send post request
    con.setDoOutput(true);
    DataOutputStream wr = new DataOutputStream(con.getOutputStream());
    wr.writeBytes(urlParameters);
    wr.flush();
    wr.close();

    int responseCode = con.getResponseCode();
}