来自Mapquest的不正确的JSON响应 - Android应用程序

Question

我正在尝试使用mapquest api从mapquest获取一个JSON对象到Android应用程序中。 JSON请求规范如下。

POST URL:
http://www.mapquestapi.com/directions/v2/route?key=[YOUR_KEY_HERE]
POST BODY:   
{
    locations:[
    "State College, PA",
    "Lancaster, PA"
    ]
}

以下代码成功建立连接，但mapquest的响应不正确。

URL url_mapquest = new URL("http://www.mapquestapi.com/directions/v2/route?key=xxxxxxxxxxxx");

HttpURLConnection connection = (HttpURLConnection) url_mapquest.openConnection();
String urlParameters = "None";
connection.setRequestMethod("POST");
connection.setRequestProperty("USER-AGENT", "Mozilla/5.0");
connection.setRequestProperty("ACCEPT-LANGUAGE", "en-US,en;0.5");
connection.setDoOutput(true);

JSONObject jsonParam = new JSONObject();
try {
    JSONArray list = new JSONArray();
    list.put("State College, PA");
    list.put("Lancaster, PA");
    jsonParam.put("locations", list);
} catch (JSONException e) {
    e.printStackTrace();
}

System.out.println("JSON String: " + jsonParam.toString());

DataOutputStream dStream = new DataOutputStream(connection.getOutputStream());
dStream.writeBytes(jsonParam.toString());
dStream.flush();
dStream.close();
int responseCode = connection.getResponseCode();

System.out.println("\nSending 'POST' request to URL : " + url_mapquest);
System.out.println("Post parameters : " + urlParameters);
System.out.println("Response Code : " + responseCode);

final StringBuilder output_Mars = new StringBuilder("Request URL : " + url_mapquest);
output_Mars.append(System.getProperty("line.separator") + "Request Parameters : " + urlParameters);
output_Mars.append(System.getProperty("line.separator") + "Response Code : " + responseCode);
output_Mars.append(System.getProperty("line.separator") + "Type : " + "POST");

String line = "";
StringBuilder responseOutput = new StringBuilder();

if (responseCode != HttpURLConnection.HTTP_FORBIDDEN) {
    BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
    System.out.println("output===============" + br);
    while ((line = br.readLine()) != null) {
        responseOutput.append(line);
    }
    br.close();
} else {
    responseOutput.append("Response Code 403 Forbidden");
}

以下是从android模拟器

中捕获的错误响应

代码中可能有什么问题？

参考文献：

• HttpURLConnection sending JSON POST request to Apache/PHP
• JSON.simple example – Read and write JSON
• JSON with Java
• Send HTTP POST Request from Java Application to Google Messaging Service
• MapQuest Platform Web Services
• Android weather app: JSON, HTTP and Openweathermap
• Android HTTP Client: GET, POST, Download, Upload, Multipart Request
• JSON Formatter & Validator

Answer 1

如何将以下内容添加到连接属性

connection.setRequestProperty("Content-Type", "application/json");
connection.setRequestProperty("Accept", "application/json");

模拟器响应中的以下注释表明应用程序可能未正确接收JSON对象。

A JSONObject text must begin with a '{' at character 0