用 Java 向 Google Elevation API 发送请求答案

【问题标题】：Send request to Google Elevation API in Java用 Java 向 Google Elevation API 发送请求
【发布时间】：2014-05-12 11:38:59
【问题描述】：

我正在尝试向 Google 海拔 API 发送 Post 请求并期待响应

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();

我正在以这种方式发送请求，但我收到的响应代码为 400。这在从浏览器发送请求时有效。这段代码有什么问题。

【问题讨论】：

标签： java google-maps-api-3 google-api

【解决方案1】：

为了让我取回 XML，我对您的项目进行了以下更改

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();

// 我将 URL 更改为 :
私有最终字符串 ELEVATION_API_URL = "https://maps.googleapis.com/maps/api/elevation/xml";

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

return response.toString();

【讨论】：

【解决方案2】：

我认为url参数有问题。

首先是因为发送一个空的海拔 api 请求确实会返回一个代码 400 (Invalid request. Missing the 'path' or 'locations' parameter.)。

其次，因为这有效（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();
}

【讨论】：