MySQLConnection Conn.Connect()

Question

我对使用数据库非常陌生，我想知道我在实现中是否犯了一些常见的设计缺陷。对于上下文，整个项目打算由单个用户使用。

我想要审查的代码：

class DatabaseConnection
{
    //properties
    private MySqlConnection _connection;
    public MySqlConnection Connection { get { return _connection; } }
    public AccountLogin AccountCredentials { get; }
    public DatabaseLogin DatabaseCredentials { get; }

    //constructor
    public DatabaseConnection(AccountLogin _AccCred,
                              DatabaseLogin _DBCred)
    {
        AccountCredentials = _AccCred;
        DatabaseCredentials = _DBCred;
    }

    public void Connect()
    {
        if (Connection != null)
        {
            return;
        }

        string[] UserInputs =
        {
            DatabaseCredentials?.DatabaseName,
            DatabaseCredentials?.Server,
            DatabaseCredentials?.Port,
            AccountCredentials?.Password,
            AccountCredentials?.Username
        };
        bool ChkInpts = Validators.NullStringValidator(UserInputs);

        if (!ChkInpts)
        {
            string ConnInfo = "server=" + DatabaseCredentials.Server + ";" +
                              "user=" + AccountCredentials.Username + ";" +
                              "database=" + DatabaseCredentials.DatabaseName +
                              "port=" + DatabaseCredentials.Port + 
                              "password=" + AccountCredentials.Password;
            _connection = new MySqlConnection(ConnInfo);

            try
            {
                Console.WriteLine("Connecting to " + DatabaseCredentials.DatabaseName + "...");
                _connection.Open();
                Console.WriteLine("Connection to " + DatabaseCredentials.DatabaseName + " successful.");
            }

            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
        }
    }
    public void Close()
    {
        _connection.Close();
    }
}

相关守则：

class AccountLogin
{
    public string Username { get; }
    public string Password { get; }

    public AccountLogin(string _username, string _password)
    {
        Username = _username;
        Password = _password;
    }
}

class DatabaseLogin
{
    public string DatabaseName { get; }
    public string Server { get; }
    public string Port { get; }

    public DatabaseLogin(string _server, string _DatabaseName, string _port)
    {
        DatabaseName = _DatabaseName;
        Server = _server;
        Port = _port;
    }
}

static class Validators
{
    public static bool NullStringValidator(string[] _inputs)
    {
        bool _result = false;
        for (int i = 0; i < _inputs.Length; i++)
        {
            if (string.IsNullOrEmpty(_inputs[i]))
            {
                return _result = true;
            }
        }
        return _result;
    }
}

Answer 1

C#中参数的常规命名是camelCase：

AccountLogin _AccCred

看上去更像

AccountLogin accountLogin

我想知道：DatabaseCredentials?.DatabaseName是否有用？如果是DatabaseCredentials is null，那么您可以连接到哪个数据库？

如果DatabaseCredentials == null的话，我会抛出一个异常。这可能也适用于AccountCredentials。

字符串连接是构建字符串的一种效率很低的方法：

而不是

string ConnInfo = "server=" + DatabaseCredentials.Server + ";" +
                              "user=" + AccountCredentials.Username + ";" +
                              "database=" + DatabaseCredentials.DatabaseName +
                              "port=" + DatabaseCredentials.Port + 
                              "password=" + AccountCredentials.Password;

使用任何一种

StringBuilder

或

String.Format("server={0};user={1};...", DatabaseCredentials.Server, AccountCredentials.Username,...);

或

字符串插值：

$"server={DatabaseCredentials.Server};user={AccountCredentials.Username};..."

MySqlConnection实现了IDisposable。因此，您的包装器也应该这样做，这样您就可以释放_connection对象，然后客户端可以像这样使用包装器：

using (DatabaseConnection dc = new DatabaseConnection(...))
{
  // Use the connection...
}

try-catch方法中的-statement对客户端没有任何用处，因为如果连接失败，则不会向客户端发出信号。要么重新抛出异常，抛出自己的新异常，要么简单地忽略这里的任何异常并让客户端处理它们。

在……里面

public void Close()
{
    _connection.Close();
}

您应该测试_connection == null。