Rest API 在 Postman 中工作，但在 Android 应用程序中无效

Question

Rest API's are working in Postman with chrome, but same requests when tried to make from the android application works only in the following scenario: In postman execute a request(say a POST request A), run the android application I'm getting the expected result for POST REQUEST A. For a different POST request(say POST REQUEST B), again i have to execute the POST REQUEST B in POSTMAN and then do the action in my application. On not executing POST REQUEST B the response of POST REQUEST A is obtained in my application.

Also after a certain period of timeout, if i simply run the android application that make POST requests, i get the following error: {"message":"Missing Authentication Token"}

The above error message is even obtained when the link provided in the url object is tried to access from a browser URL url = new URL("LINK");

What could be the reasons for the above issues?

Code snippet:

    URL url = new URL(LINK); 
    con = (HttpURLConnection) url.openConnection();
    InputStream errorStream = con.getErrorStream();
    if (errorStream != null) {
         BufferedReader br1 = new BufferedReader(new 
         InputStreamReader(errorStream));
         String errorInConnection = readStream(br1);
         Log.d(TAG, "errorInConnection:"+errorInConnection);
         }
    con.setRequestProperty("Authorization", "no auth");
    con.setRequestMethod("POST");
    con.setRequestProperty("Content-Type", "application/json");
    con.setRequestProperty("Accept", "application/json");
    con.setDoOutput(true);
    con.setChunkedStreamingMode(0);

In POSTMAN:

        {
             "data": {
                "currLat":some cordinate,
                "currLong":some coordinate
              },
              "datatype": "geodata"
        }

Header:
Key - Content-Type
Value - application/json

Answer 1

Corrections for my below answer are most welcome, also I would like to mention that I am new to android as well as handling REST API's

The reason for why I was not getting a response is because I was not posting the data correctly. As mentioned, in my case I was suppose to post JSON data. While posting JSON data even small mistakes like posting "latitude":12.321 for "latitude":"12.321" must not be done. The syntax must be followed. If you are posting wrong data you will be getting the below type of error:

{"errorMessage":"java.lang.NullPointerException","errorType":"java.lang.NullPointerException","stackTrace":["java.io.Writer.write(Writer.java:157)","com.bosch.in.dataloggerlambda.StramDataProcessosLambda.handleRequest(StramDataProcessosLambda.java:102)","sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)","sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)","sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)","java.lang.reflect.Method.invoke(Method.java:498)"]}

If responses are obtained in postman then we will get the responses from HttpUrlConnection made from android studio.

Since the url I had was for post and for post, data must be present to get a response, when I pasted the link in the browser it gave me the below error:

error: {"message":"Missing Authentication Token"}

The same thing was observed from android studio as well. There can be many other cases for which you might get the same error, I'm not sure of those. But make sure even from android studio while trying to make a POST request you need to send the data.