Question

我有Thread的包装类：

public class ThreadWrapper
    {
        private bool Terminated = false;
        private string threadName;
        private Thread _thread;

        public bool needToTerminate
        {
            get
            {
                lock (this)
                {
                    return Terminated;
                }
            }
        }

        public string ThreadName
        {
            get
            {
                lock (this)
                {
                    return threadName;
                }
            }
        }

        // for override constructor in derived classes
        public ThreadWrapper()
        {
        }

        public ThreadWrapper(string threadName)
        {
            this.threadName = threadName;
        }

        public virtual void Run()
        {
        }

        public virtual void Terminate()
        {
            lock (this)
            {
                Terminated = true;
            }
        }

        public void Start()
        {
            lock (this)
            {
                if (_thread == null)
                {
                    _thread = new Thread(Run);
                    _thread.Start();
                }
            }
        }
    }

然后我从ThreadWrapper创建派生类：

public delegate void ProcessMessageDelegate(string message);

public class Reader : ThreadWrapper
{
    private ProcessMessageDelegate ProcessMessage;

    public Reader(ProcessMessageDelegate processMessage)
        : base() 
    {
        this.ProcessMessage = processMessage;
    }

    public override void Run()
    {
        // Do something
    }
}

我也有两个按钮的表格。开始线程的第一个按钮，第二个按钮用于＆＃34;自我终止＆＃34;线程。

public partial class MainForm : Form
    {
        private MyReader Reader;

        public MainForm()
        {
            InitializeComponent();
        }

        // real method for delegate
        private void ProcessMessage(string message)
        {
            // add line to RichEdit
            this.AddSpRRecordLog(message);
        }

        private void buttonRunTest_Click(object sender, EventArgs e)
        {
            if (MyReader == null)
            {
                MessageBox.Show("Wrong!");
                return;
            }

            MyReader.Start();
        }

        private void buttonStopTest_Click(object sender, EventArgs e)
        {
            if (MyReader == null)
            {
                MessageBox.Show("Wrong!");
                return;
            }

            MyReader.Terminate();
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            Reader MyReader = new Reader(new ProcessMessageDelegate(ProcessMessage));               
        }

如果我使用这种方式（在MyReader事件上创建FormLoad） - MyReader无法创建。如果我在buttonRunTest_Click创建了阅读，那么一切正常，但在这种情况下，我无法终止MyReader。

Answer 1

这声明了一个名为MyReader的局部变量，它隐藏了MyReader字段：

    private void MainForm_Load(object sender, EventArgs e)
    {
        Reader MyReader = new Reader(new ProcessMessageDelegate(ProcessMessage));               
    }

相反，只需指定字段：

    private void MainForm_Load(object sender, EventArgs e)
    {
        MyReader = new Reader(new ProcessMessageDelegate(ProcessMessage));               
    }

（顺便说一下，这不是传统意义上的全局变量 - 如果创建了MainForm的另一个实例，它将拥有自己独立的MyReader字段

使用one作为全局变量时，不会创建对象

1 个答案: