Question

IIS上的WCF服务。我从web.config文件中读取连接字符串时遇到问题。我的连接字符串如下所示：

    <connectionStrings>
  <add 
    name="ABC" 
    connectionString="DEF"
    providerName="GGG"
  />
</connectionStrings>

我在Global.asax.cs中的代码：

protected void Application_Start(object sender, EventArgs e)
        {                    

           cons_Webdata =  WebConfigurationManager.ConnectionStrings["ABC"].ConnectionString;

        }

我在“cons_Webdata = .......”中有错误消息：

对象引用未设置为对象的实例。

怎么了？感谢。

Answer 1

尝试使用ConfigurationManager而不是WebConfigurationManager

protected void Application_Start(object sender, EventArgs e)
{                    
    cons_Webdata =  ConfigurationManager.ConnectionStrings["ABC"].ConnectionString;
}

否则，请使用http://msdn.microsoft.com/en-us/library/ms178411.aspx

中的代码示例

        System.Configuration.Configuration rootWebConfig =
            System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("/MyWebSiteRoot");
        System.Configuration.ConnectionStringSettings connString;
        if (rootWebConfig.ConnectionStrings.ConnectionStrings.Count > 0)
        {
            connString =
                rootWebConfig.ConnectionStrings.ConnectionStrings["NorthwindConnectionString"];
            if (connString != null)
                Console.WriteLine("Northwind connection string = \"{0}\"",
                    connString.ConnectionString);
            else
                Console.WriteLine("No Northwind connection string");
        }

Answer 2

查看如何在Web应用程序here中使用WebConfigurationManager。您需要从配置文件中读取连接字符串部分，然后使用它们，如下所示：

           // Get the connectionStrings section.
            ConnectionStringsSection connectionStringsSection =
                WebConfigurationManager.GetSection("connectionStrings")
                as ConnectionStringsSection;

            // Get the connectionStrings key,value pairs collection.
            ConnectionStringSettingsCollection connectionStrings =
                connectionStringsSection.ConnectionStrings;

            // Get the collection enumerator.
            IEnumerator connectionStringsEnum =
                connectionStrings.GetEnumerator();

            // Loop through the collection and 
            // display the connectionStrings key, value pairs.
            int i = 0;
            Console.WriteLine("[Display the connectionStrings]");
            while (connectionStringsEnum.MoveNext())
            {
                string name = connectionStrings[i].Name;
                Console.WriteLine("Name: {0} Value: {1}",
                name, connectionStrings[name]);
                i += 1;
            }

从web.config读取连接字符串

2 个答案: