初始化的FileStream和StreamWriter领域中的服务类 [英] Initializing FileStream and StreamWriter fields in a service class

问题描述

我做的方法以外的代码，因为我需要关闭和处置的StreamWriter和FILESTREAM在调用OnStop（）方法：

I made this code outside the methods because I need to close and dispose the streamwriter and filestream in the OnStop() method:

private Timer timer = new Timer();
private FileStream fs = new FileStream(@"D:\Hello.txt", FileMode.Append, FileAccess.Write, FileShare.ReadWrite);
private StreamWriter sw = new StreamWriter(fs);
//The fs is in red line, having error

不过，里面的FS新的StreamWriter提示错误字段初始不能引用非静态字段，方法或属性..。所以我做了静态的FileStream：

However, the fs inside the new StreamWriter prompts the error "A field initializer cannot reference the non-static field, method, or property..". So I made the FileStream static:

private static FileStream fs = new FileStream(@"D:\Hello.txt", FileMode.Append, FileAccess.Write, FileShare.ReadWrite);

当我运行此程序，它不会写入文本文件，并认为这是因为静态的。我搜索一下，阅读这 ：一个类可以声明为static，这表明它仅包含静态成员是无法创建使用new关键字静态类的实例静态类由.NET Framework公共语言运行时（CLR）自动加载时。含有类节目或命名空间被载入

When I ran the program, it doesn't write to the textfile and concluded that it's because of the static. I searched about it and read this: "A class can be declared static, indicating that it contains only static members. It is not possible to create instances of a static class using the new keyword. Static classes are loaded automatically by the .NET Framework common language runtime (CLR) when the program or namespace containing the class is loaded."

这是我的示例代码：

public partial class Service1 : ServiceBase
{
    private Timer timer = new Timer();
    private FileStream fs = new FileStream(@"D:\Hello.txt", FileMode.Append, FileAccess.Write, FileShare.ReadWrite);
    private StreamWriter sw = new StreamWriter(fs);
//The fs is in red line, having error. Look in my description for error's details
    public Service1()
    {
        InitializeComponent();
    }

    protected override void OnStart(string[] args)
    {
        timer.Elapsed += new ElapsedEventHandler(WriteText);
        timer.Interval = 5000; //5 seconds
        timer.Start();
    }

    public void WriteText(object source, ElapsedEventArgs e)
    {
        sw.WriteLine(DateTime.Now + " Windows Service");
    }
    protected override void OnStop()
    {
        sw.Close();
        sw.Dispose();
        fs.Close();
        fs.Dispose();
        timer.Stop();
    }
}

你觉得我应该怎么办？

What do you think should I do?

推荐答案

您已经做了我应该做工精细，但它不这样做的好方法，所以它不是值得探讨，为什么它不工作。在一类具有静态变量不会使类的静态

What you have done should work fine, but it's not a good way to do it, so it's not worth investigating why it's not working. Having static variables in a class doesn't make the class static.

只是声明变量没有initialisers，然后设置变量的时候要打开文件：

Just declare the variables without initialisers, then set the variables when you want to open the file:

public partial class Service1 : ServiceBase
{
    private Timer timer;
    private FileStream fs;
    private StreamWriter sw

    public Service1()
    {
        InitializeComponent();
    }

    protected override void OnStart(string[] args)
    {
        fs = new FileStream(@"D:\Hello.txt", FileMode.Append, FileAccess.Write, FileShare.ReadWrite);
        sw = new StreamWriter(fs);
        timer = new Timer();
        timer.Elapsed += new ElapsedEventHandler(WriteText);
        timer.Interval = 5000; //5 seconds
        timer.Start();
    }

    public void WriteText(object source, ElapsedEventArgs e)
    {
        sw.WriteLine(DateTime.Now + " Windows Service");
    }
    protected override void OnStop()
    {
        timer.Stop(); // Stop the timer before closing the file
        sw.Close();
        sw.Dispose();
        fs.Close();
        fs.Dispose();
    }
}

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