Android facebook第三方登录生成散列码

public static String printKeyHash(Activity context) {
PackageInfo packageInfo;
String key = null;
try {
//getting application package name, as defined in manifest
String packageName = context.getApplicationContext().getPackageName();

//Retriving package info
packageInfo = context.getPackageManager().getPackageInfo(packageName,
PackageManager.GET_SIGNATURES);

Log.e("Package Name=", context.getApplicationContext().getPackageName());

for (Signature signature : packageInfo.signatures) {
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(signature.toByteArray());
key = new String(Base64.encode(md.digest(), 0));

// String key = new String(Base64.encodeBytes(md.digest()));
Log.e("Key Hash=", key);
}
} catch (PackageManager.NameNotFoundException e1) {
Log.e("Name not found", e1.toString());
}
catch (NoSuchAlgorithmException e) {
Log.e("No such an algorithm", e.toString());
} catch (Exception e) {
Log.e("Exception", e.toString());
}

return key;
}