c# - 从 connection.cs 文件中调用连接字符串

Question

代码有问题吗？？它不起作用并抛出异常对象参考。未设置为对象实例。异常位于代码行字符串 DbConnectionString = Connection.ConnectionString处的 datageneric.cs 文件中；

连接.cs

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.Configuration;
    public static class Connection
    {
    private static string constr = "server=.;database=foood;";
        public static string ConnectionString
        {
    get
    {
        return constr;
    }
    set
    {
        constr = value;
    }
}
public static string ProviderName { get; set; }
static Connection()
{
    ConnectionString =WebConfigurationManager.ConnectionStrings["constring"].ConnectionString;
    ProviderName = WebConfigurationManager.ConnectionStrings["constring"].ProviderName;
}
    }

DataGeneric.cs

        public static DbCommand CreateCommand()
{
    DbCommand cmd=null;
    try
    {
        string DbConnectionString = Connection.ConnectionString;
        string DbProviderName = Connection.ProviderName;
        DbProviderFactory factory = DbProviderFactories.GetFactory(DbProviderName);
        DbConnection conn = factory.CreateConnection();
        conn.ConnectionString = DbConnectionString;
        cmd = conn.CreateCommand();
        cmd.CommandType = CommandType.Text;
    }
    catch (Exception ex) { }
    return cmd;
}

获取数据.cs

        public static DataTable gimmedata()
{
    string Query = "select * from [slider]";
    DbCommand cmd = DataGeneric.CreateCommand();
    cmd.CommandText = Query;
    DataTable dt = DataGeneric.ExecuteSelectCommand(cmd);
    return dt;
}

默认.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    DataTable dt = GetData.gimmedata();
    GridView1.DataSource = dt;
    GridView1.DataBind();

}

Answer 1

您的连接类是public static. 因此，要使用它的变量，请在其中创建它object，DataGeneric.cs然后通过该对象访问该类。

Connection con = new Connection();

string DbConnectionString = con.ConnectionString;

希望有效。