When using an encrypted database, onDowngrade is not supported, and the database will crash when it is downgraded

[zhaolifan]

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使用加密数据库时，通过getEncryptedWritableDb获取EncryptedHelper，EncryptedHelper不支持onDowngrade，数据库降级时会崩溃

When using an encrypted database, get the EncryptedHelper through getEncryptedWritableDb. EncryptedHelper does not support onDowngrade, and the database will crash when it is downgraded

[greenrobot-team]

The greenDAO API is using a rather outdated version of the SQLite and SQLCipher APIs which did not support onDowngrade(), yet. A workaround is to write a custom open helper and manually call the relevant DaoMaster methods. Then pass whatever Database got created to DaoMaster(database).