winform实现嵌套类访问父类的控件[原创]

CSDN上看到别人提了这个问题，线程和控件调用冲突之类的见过不少，嵌套类没有试过，便尝试写下

public delegate void DoEvent();

    public partial class Form1 : Form
    {
        checkFlowThread td;
        DoEvent toDo;

        public Form1()
        {
            InitializeComponent();
            toDo = new DoEvent(checkFlow);
            if (td == null)
                td = new checkFlowThread(this);
            this.Load += (sender, e) => checkFlow();
        }

        private void checkFlow()
        {
            if (this.InvokeRequired)
            {
                this.Invoke(toDo);
            }
            else
            {
                td.checkFlow();
            }
        }

        //这是一个嵌套类
        public class checkFlowThread
        {
            Form1 from;
            public checkFlowThread(Form1 f)
            {
                from = f;
                DoEvent todo = new DoEvent(checkFlow);
            }

            public void checkFlow()
            {

                from.label1.Text = "想访问外部类的非静态成员";
            }
        }
    }

　　这样label1可以被修改