如果条件如何解决fieldinfo错误？ [英] How to resolve fieldinfo error if condition?

问题描述

你好，



我写了这段代码但收到错误： -

Hello,

I have write this code but its getting error:-

acceptedCommandsFieldInfo is a field but is used like a type

请帮我解决这个错误。



预付款。



Ankit Agarwal

软件工程师



我尝试过：

Pleas help me how to resolve this error.

Thanks in Advance.

Ankit Agarwal
Software Engineer

What I have tried:

class MyService
    {
        const int SERVICE_ACCEPT_PRESHUTDOWN = 0x100;
        const int SERVICE_CONTROL_PRESHUTDOWN = 0xf;
        FieldInfo acceptedCommandsFieldInfo =
        typeof(ServiceBase).GetField("acceptedCommands", BindingFlags.Instance | BindingFlags.NonPublic);
        if (acceptedCommandsFieldInfo == null)// Error in this line
            throw ApplicationException("acceptedCommands field not found");// Error in this line
    
            int value = (int)acceptedCommandsFieldInfo.GetValue(this);// Error in this line
            acceptedCommandsFieldInfo.SetValue(this, value SERVICE_ACCEPT_PRESHUTDOWN);// Error in this line
    }

推荐答案

问题是您正在类中运行此代码。你不能这样做，你必须在你班上的方法中运行代码。



看起来你想创建一个服务？然后将它放在 OnStart 函数中（但是你的类也必须从ServiceBase派生）。同样在最后一行中，传递值SERVICE_ACCEPT_PRESHUTDOWN，它看起来像两个变量。你只能通过一个。我不确切地知道你要做什么，所以你必须知道自己要通过哪一个（但我想它将是SERVICE_ACCEPT_PRESHUTDOWN）。此外，您必须使用抛出新的ApplicationException 而不是抛出ApplicationException 。

The problem is that you are running this code right in the class. You cannot do this, you have to run the code in a method in your class.

It looks like you want to create a service? Then put it in an OnStart function (but then your class has to derive from ServiceBase, too). Also in your last line, you pass "value SERVICE_ACCEPT_PRESHUTDOWN" which look like two variables. You can only pass one. I don't know exactly what you try to do, so you have to know yourself which one to pass there (but I guess it will be SERVICE_ACCEPT_PRESHUTDOWN). Also, you have to use throw new ApplicationException instead of throw ApplicationException.

class MyService : ServiceBase
{
    protected override void OnStart(string[] args)
    {
            FieldInfo acceptedCommandsFieldInfo = typeof(ServiceBase).GetField("acceptedCommands", BindingFlags.Instance | BindingFlags.NonPublic);
            if (acceptedCommandsFieldInfo == null)
                throw new ApplicationException("acceptedCommands field not found");
    
            int value = (int)acceptedCommandsFieldInfo.GetValue(this);
            acceptedCommandsFieldInfo.SetValue(this, SERVICE_ACCEPT_PRESHUTDOWN);
    }
}

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