For those who want to check subscription status on Google's AppEngine with Java, here is my working example based on many codes found on SO. I spent couple of days to solve many mistakes caused by lack of experience. I see lot of suggestions to check subscription status on server but it was not easy for me to do on AppEngine. Without answers found on SO, I could not come up with this.
Step 1
First we need to go through "Prerequisite" section found on Jonathan Naguin's answer, until you get code from web browser. Now you have;
- Client ID
- Client secret
- Redirect URI
- code
ready.
Note we run all codes shown below on AppEngine. And I used logger like this.
static final Logger log = Logger.getLogger(MyClassName.class.getName());
Step 2
We need to get refresh token. Run code shown below after replacing [YOUR CLIENT ID], [YOUR CLIENT SECRET], [YOUR CODE], [YOUR REDIRECT URI] with your string.
private String getRefreshToken()
{
try
{
Map<String,Object> params = new LinkedHashMap<>();
params.put("grant_type","authorization_code");
params.put("client_id",[YOUR CLIENT ID]);
params.put("client_secret",[YOUR CLIENT SECRET]);
params.put("code",[YOUR CODE]);
params.put("redirect_uri",[YOUR REDIRECT URI]);
StringBuilder postData = new StringBuilder();
for(Map.Entry<String,Object> param : params.entrySet())
{
if(postData.length() != 0)
{
postData.append('&');
}
postData.append(URLEncoder.encode(param.getKey(),"UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(param.getValue()),"UTF-8"));
}
byte[] postDataBytes = postData.toString().getBytes("UTF-8");
URL url = new URL("https://accounts.google.com/o/oauth2/token");
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.getOutputStream().write(postDataBytes);
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuffer buffer = new StringBuffer();
for (String line = reader.readLine(); line != null; line = reader.readLine())
{
buffer.append(line);
}
JSONObject json = new JSONObject(buffer.toString());
String refreshToken = json.getString("refresh_token");
return refreshToken;
}
catch (Exception ex)
{
log.severe("oops! " + ex.getMessage());
}
return null;
}
Since refresh token won't expire, we can save it somewhere or simply hard-code in our code. (We only need to run above code once to get refresh token.)
Step 3
We need to get access token. Run code shown below after replacing [YOUR CLIENT ID], [YOUR CLIENT SECRET], [YOUR REFRESH TOKEN] with your string.
private String getAccessToken()
{
try
{
Map<String,Object> params = new LinkedHashMap<>();
params.put("grant_type","refresh_token");
params.put("client_id",[YOUR CLIENT ID]);
params.put("client_secret",[YOUR CLIENT SECRET]);
params.put("refresh_token",[YOUR REFRESH TOKEN]);
StringBuilder postData = new StringBuilder();
for(Map.Entry<String,Object> param : params.entrySet())
{
if(postData.length() != 0)
{
postData.append('&');
}
postData.append(URLEncoder.encode(param.getKey(),"UTF-8"));
postData.append('=');
postData.append(URLEncoder.encode(String.valueOf(param.getValue()),"UTF-8"));
}
byte[] postDataBytes = postData.toString().getBytes("UTF-8");
URL url = new URL("https://accounts.google.com/o/oauth2/token");
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.getOutputStream().write(postDataBytes);
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuffer buffer = new StringBuffer();
for (String line = reader.readLine(); line != null; line = reader.readLine())
{
buffer.append(line);
}
JSONObject json = new JSONObject(buffer.toString());
String accessToken = json.getString("access_token");
return accessToken;
}
catch (Exception ex)
{
log.severe("oops! " + ex.getMessage());
}
return null;
}
Step 4
What I wanted to know is just expire UTC of the subscription. Code shown below returns expire UTC, 0 when found error. You need to provide your package name, product id (=subscription id), access token you got on Step 3, and purchase token found in your purchase data.
private long getExpireDate(String packageName,String productId,String accessToken,String purchaseToken)
{
try
{
String charset = "UTF-8";
String query = String.format("access_token=%s",URLEncoder.encode(accessToken,charset));
String path = String.format("https://www.googleapis.com/androidpublisher/v1/applications/%s/subscriptions/%s/purchases/%s",packageName,productId,purchaseToken);
URL url = new URL(path + "?" + query);
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
connection.setRequestProperty("Accept-Charset",charset);
connection.setRequestMethod("GET");
BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
StringBuffer buffer = new StringBuffer();
for(String line = reader.readLine(); line != null; line = reader.readLine())
{
buffer.append(line);
}
JSONObject json = new JSONObject(buffer.toString());
return json.optLong("validUntilTimestampMsec");
}
catch (Exception ex)
{
log.severe("oops! " + ex.getMessage());
}
return 0;
}
Note product id or subscription id is a string found on developer console. Your subscription item appears with name/id column. It looks like this.
Description of item(product id)
Last step (fun part)
Now we have all components to verify subscription is valid or not. I did like this. You need to replace [YOUR PACKAGE NAME], [YOUR PRODUCT ID] with yours.
You need to provide purchase data which you can get with Purchase#getOriginalJson() found in iabHelper code.
private boolean checkValidSubscription(String purchaseData)
{
String purchaseToken;
JSONObject json;
try
{
json = new JSONObject(purchaseData);
}
catch (JSONException e)
{
log.severe("purchaseData is corrupted");
return true; // false positive
}
purchaseToken = json.optString("purchaseToken");
if(purchaseToken.length() == 0)
{
log.severe("no purchase token found");
return true; // false positive
}
String accessToken = getAccessToken();
if(accessToken == null)
{
return true; // false positive
}
long expireDate = getExpireDate([YOUR PACKAGE NAME],[YOUR PRODUCT ID],accessToken,purchaseToken);
if(expireDate == 0)
{
log.severe("no expire date found");
return true; // false positive
}
expireDate += 86400000l; // add one day to avoid mis judge
if(expireDate < System.currentTimeMillis())
{
log.severe("subscription is expired");
return false;
}
// just for log output
long leftDays = (expireDate - System.currentTimeMillis()) / 86400000l;
log.info(leftDays + " days left");
return true;
}
Note for debugging
Google returns JSON string for response. If code won't work as expected, logging JSON string may help understanding what is wrong.
I hope this helps someone.
