Question

我正在尝试使用Windows窗体应用程序上的按钮单击启动和停止Windows服务，但是当我单击开始按钮时，它会发出以下错误：

Object reference not set to an instance of an object.

这是我的Windows窗体应用程序的源代码

public partial class Form1 : Form
{
    string svcStatus;
    ServiceController myService;

    public Form1()
    {
        InitializeComponent();

        ServiceController myService = new ServiceController();
        myService.ServiceName = "ServiceName";
        svcStatus = myService.Status.ToString();
    }


    private void button1_Click(object sender, EventArgs e)
    {
        if (svcStatus == "Stopped")
        {
            myService.Start();   // START the service if it is already Stopped

            string svcStatusWas = "";  
            while (svcStatus != "Running")
            {
                if (svcStatus != svcStatusWas)
                {
                    Console.WriteLine("Status: " + svcStatus);
                }

                svcStatusWas = svcStatus;

                myService.Refresh();
                svcStatus = myService.Status.ToString();
            }
            Console.WriteLine("Service Started!!");
        }
    }

    private void button2_Click(object sender, EventArgs e)
    {
        if (svcStatus == "Running")
        {                
            myService.Stop();   // STOP the service if it is already Running

            string svcStatusWas = "";   
            while (svcStatus != "Stopped")
            {

                svcStatusWas = svcStatus;

                myService.Refresh();    
                svcStatus = myService.Status.ToString();
            }
            Console.WriteLine("Service Stopped!!");
        }
    }

}

svcStatus我正在停止。请帮助我。

Answer 1

在Form1（）中，您有：

    ServiceController myService = new ServiceController();
    myService.ServiceName = "ServiceName";
    svcStatus = myService.Status.ToString();

声明ServiceController的本地实例。点击处理程序正在使用永远不会被初始化的类成员myService。

将上述三行中的第一行更改为

    myService = new ServiceController();

它应该有用。

在按钮Click上启动Windows服务时，对象引用未设置为对象的实例

1 个答案: