访问请求JSONObject时出错

Question

我正在开发一个android应用程序，其中android移动客户端通过Flask REST API与服务器通信。特定的移动设备间歇地接收来自服务器的400个POST端点响应。

以下是相关的服务器端代码:

def post(self):
            app.logger.info("Request :" + request.url)
            if request.headers['Content-Type'] == "application/json":
                    tok = str(request.json['tok'])
                    user_id = str(request.json['user_id'])
                    contact = str(request.json['contact'])   
                    .
                    .
                    .
            else:
                    response = jsonify({"message": "Unsupported Media Type"})
                    response.status_code = 415
                    return response

一旦在if条件内访问到请求json对象，就返回Response 400。

下面是用于编码json对象和执行post请求的android java代码:

    HttpParams httpParameters = new BasicHttpParams();
    HttpConnectionParams.setConnectionTimeout(httpParameters,Constants.HTTP_CONNECTION_TIMEOUT);
    HttpConnectionParams.setSoTimeout(httpParameters, Constants.HTTP_SOCKET_TIMEOUT);
    HttpClient client = new DefaultHttpClient(httpParameters);
    URL url = null;
    URI uri = null;
    try {
        url = new URL(Constants.URL+"api/v1/testapi");
        uri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
    } catch (MalformedURLException e3) {
        e3.printStackTrace();
    } catch (URISyntaxException e) {
        e.printStackTrace();
    }
    HttpPost post = new HttpPost(uri.toString());
    final JSONObject msgObject = jObject[0];
    StringEntity se = null;
    try {
        se = new StringEntity(msgObject.toString());
    } catch (UnsupportedEncodingException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
    se.setContentType(new BasicHeader(HTTP.CONTENT_TYPE,"application/json"));
    post.setEntity(se);
    boolean postFailed = false;
    try {
        HttpResponse response = client.execute(post);
        Log.v(TAG,response.getStatusLine().toString());
        if(response.getStatusLine().toString().indexOf("200")!=-1){
            HttpEntity httpEntity = response.getEntity();
            InputStream is = httpEntity.getContent();
            JSONParser parseJSON = new JSONParser();
            JSONObject JO = parseJSON.getJSONObj(is);
            .
            .
            .
            }
            is.close();
        }else
            postFailed = true; 
    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        postFailed = true;
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        postFailed = true;
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        postFailed = true;
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        postFailed = true;
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        postFailed = true;
    }

msgObject是JSONObject类型，它包含所有期望的键值对。

关于这个问题奇怪的部分是，主要发生在一个特定的移动客户端(太间歇性)，请让我知道如果你们有任何建议如何解决这个问题。谢谢!

Answer 1

判断Flask中是否设置了正确的JSON内容类型的最好方法是使用is_json函数。即使出于某种原因不想使用此方法，也应该像下面这样使用if语句

if "application/json" in request.headers["Content-Type"]:

这里的问题是，大多数客户端不只是把application/json在Content-Type，但也编码，所以头结果像这样:

Content-Type: application/json; charset=utf-8

希望现在一切都清楚了