C# DLL中未初始化静态只读变量

我有一个DLL，我正试图在另一个程序中使用。这是导致一些问题的部分：

从我的dll:

public class fService
{
    public static readonly string connectionString = "My connection string";
    ...
    etc
    ...
    public static void myStaticMethod()
    {
        fStat x = new fStat();
    }
}

private void btnSave_Click(object sender, EventArgs e)
{
    try
    {
        fService.myStaticMethod();
        MessageBox.Show("Success!");
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

at System.Data.SqlClient.SqlConnection.PermissionDemand()
   at System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at fManager.tableClasses.fStats..ctor() in e:\fManager\project\fManager\ConsoleApplication1\tableClasses\fStats.cs:line 55
   at fManager.fService.constructElement(String header, String content, fService& service) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 964
   at fManager.fService.LoadIni(String path) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 675
   at fManagerF.mainForm.btnSave_Click(Object sender, EventArgs e) in e:\fManager\exeProject\fManagerF\fManager\mainForm.cs:line 54

public fStat()
{
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand cmd = new SqlCommand("fManager.getfStats", conn);
        SqlCommand cmdCount = new SqlCommand("SELECT COUNT(*) FROM [fManager].[fStats]", conn);
        _id = 0;
        cmd.CommandType = System.Data.CommandType.StoredProcedure;
        conn.Open();
        _id = (int)cmdCount.ExecuteScalar();
        cmd.ExecuteNonQuery();
        conn.Close();
    }
}

来自我的其他程序：

public class fService
{
    public static readonly string connectionString = "My connection string";
    ...
    etc
    ...
    public static void myStaticMethod()
    {
        fStat x = new fStat();
    }
}

private void btnSave_Click(object sender, EventArgs e)
{
    try
    {
        fService.myStaticMethod();
        MessageBox.Show("Success!");
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

at System.Data.SqlClient.SqlConnection.PermissionDemand()
   at System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at fManager.tableClasses.fStats..ctor() in e:\fManager\project\fManager\ConsoleApplication1\tableClasses\fStats.cs:line 55
   at fManager.fService.constructElement(String header, String content, fService& service) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 964
   at fManager.fService.LoadIni(String path) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 675
   at fManagerF.mainForm.btnSave_Click(Object sender, EventArgs e) in e:\fManager\exeProject\fManagerF\fManager\mainForm.cs:line 54

public fStat()
{
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand cmd = new SqlCommand("fManager.getfStats", conn);
        SqlCommand cmdCount = new SqlCommand("SELECT COUNT(*) FROM [fManager].[fStats]", conn);
        _id = 0;
        cmd.CommandType = System.Data.CommandType.StoredProcedure;
        conn.Open();
        _id = (int)cmdCount.ExecuteScalar();
        cmd.ExecuteNonQuery();
        conn.Close();
    }
}

我得到的例外情况是，

ConnectionString属性尚未初始化。

为什么会这样？如何正确初始化它？类fService必须是静态的吗（我希望避免这种情况）

StackTrace:

public class fService
{
    public static readonly string connectionString = "My connection string";
    ...
    etc
    ...
    public static void myStaticMethod()
    {
        fStat x = new fStat();
    }
}

private void btnSave_Click(object sender, EventArgs e)
{
    try
    {
        fService.myStaticMethod();
        MessageBox.Show("Success!");
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

at System.Data.SqlClient.SqlConnection.PermissionDemand()
   at System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at fManager.tableClasses.fStats..ctor() in e:\fManager\project\fManager\ConsoleApplication1\tableClasses\fStats.cs:line 55
   at fManager.fService.constructElement(String header, String content, fService& service) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 964
   at fManager.fService.LoadIni(String path) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 675
   at fManagerF.mainForm.btnSave_Click(Object sender, EventArgs e) in e:\fManager\exeProject\fManagerF\fManager\mainForm.cs:line 54

public fStat()
{
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand cmd = new SqlCommand("fManager.getfStats", conn);
        SqlCommand cmdCount = new SqlCommand("SELECT COUNT(*) FROM [fManager].[fStats]", conn);
        _id = 0;
        cmd.CommandType = System.Data.CommandType.StoredProcedure;
        conn.Open();
        _id = (int)cmdCount.ExecuteScalar();
        cmd.ExecuteNonQuery();
        conn.Close();
    }
}

这就是问题的根源：

public class fService
{
    public static readonly string connectionString = "My connection string";
    ...
    etc
    ...
    public static void myStaticMethod()
    {
        fStat x = new fStat();
    }
}

private void btnSave_Click(object sender, EventArgs e)
{
    try
    {
        fService.myStaticMethod();
        MessageBox.Show("Success!");
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

at System.Data.SqlClient.SqlConnection.PermissionDemand()
   at System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at fManager.tableClasses.fStats..ctor() in e:\fManager\project\fManager\ConsoleApplication1\tableClasses\fStats.cs:line 55
   at fManager.fService.constructElement(String header, String content, fService& service) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 964
   at fManager.fService.LoadIni(String path) in e:\fManager\project\fManager\ConsoleApplication1\fService.cs:line 675
   at fManagerF.mainForm.btnSave_Click(Object sender, EventArgs e) in e:\fManager\exeProject\fManagerF\fManager\mainForm.cs:line 54

public fStat()
{
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand cmd = new SqlCommand("fManager.getfStats", conn);
        SqlCommand cmdCount = new SqlCommand("SELECT COUNT(*) FROM [fManager].[fStats]", conn);
        _id = 0;
        cmd.CommandType = System.Data.CommandType.StoredProcedure;
        conn.Open();
        _id = (int)cmdCount.ExecuteScalar();
        cmd.ExecuteNonQuery();
        conn.Close();
    }
}

---

编辑：如果您投票否决/投票关闭，请告诉我原因。我觉得我已经提供了所有的信息，我仍然停留在topid上，但是请让我知道我失败的地方，以帮助我改进=）

您将

connectionString

属性定义为

fService

类的静态成员，但是您在

fStat

类中使用了变量

connectionString

。这不是同一个变量。您的

fService.connectionString

已初始化，而您的

fStat.connectionString

未初始化。因此，

SqlConnection

中的

ConnectionString

也未初始化，因此出现错误。

显示

的代码。
这是使用ConnectionString的地方。

和实际堆栈跟踪。您得到的错误不是.NET运行时抛出的错误，它谈论的是您的

connectionString

成员，而是一些数据库连接代码。显示堆栈跟踪。代码看起来是正确的！这样一个初学者的东西错过了，我感到尴尬^^^无论如何，谢谢你的帮助！