Android Facebook Key Hash Stopped Working

问题:

I am creating an Android app that will integrate with Facebook. I have been able to successfully generate a Key Hash, and when I run my app to log in, I successfully got to the accept permissions button. I clicked accept and since then, I haven't been able to log back in from the app. I am given the error "(insert the key has i'm using here) does not match any allowed key. Configure your app key hashes at (lists my Facebook developer URL)". Is there any reason why a Key Hash would work and then would just stop? I did not alter any facebook settings and did not alter any application code. I've tried creating a new key hash, but that still didn't work. Any ideas on what this could be, or how to resolve it would be greatly appreciated!

回答1:

I figured this out. Somehow, the Hash Key just stopped matching what I had inserted on the Facebook side. Using the facebook documentation, I added in code in my onCreate method that told me what the hash key was in my LogCat. I also added in some logging code for my catch exceptions in the event that I was screwing up my package name. This is the code:

try {
            PackageInfo info = getPackageManager().getPackageInfo(
                    "com.your.package", 
                    PackageManager.GET_SIGNATURES);
            for (Signature signature : info.signatures) {
                MessageDigest md = MessageDigest.getInstance("SHA");
                md.update(signature.toByteArray());
                Log.d("KeyHash:", Base64.encodeToString(md.digest(), Base64.DEFAULT));
                }
        } catch (NameNotFoundException e) {
            Log.d("Error1", "NameNotFoundException");

        } catch (NoSuchAlgorithmException e) {
            Log.d("Error2", "Algorthim");

        }

After I added that and ran it, I found the hash key in my log cat, and then just copied that to my Facebook App. Saved it, ran the app again and it worked!