解决移动端文件删除的安全问题：file.delect()
Java 确保安全删除某个文件
http://outofmemory.cn/code-snippet/14222/Java-security-delete-file
Safe way to delete files in Android development
https://stackoverflow.com/questions/53242122/safe-way-to-delete-files-in-android-development （这个是解释）
http://outofmemory.cn/code-snippet/14222/Java-security-delete-file
Safe way to delete files in Android development
https://stackoverflow.com/questions/53242122/safe-way-to-delete-files-in-android-development （这个是解释）