displayPassword method
Implementation
String displayPassword(String password) {
if (password == null) return "null";
if (password == "888888") return "初始密码";
if (password.length > 6)
return "${password.substring(0, 2)}****${password.substring(password.length - 2)}";
if (password.length > 3)
return "****${password.substring(password.length - 2)}";
return "随机密码***$password";
}