winform异步进度条LongTime,运用到回调函数
定义事件的参数类:
namespace LongTime.Business
{
// 定义事件的参数类
public class ValueEventArgs
: EventArgs
{
public int Value { set; get;}
} // 定义事件使用的委托
public delegate void ValueChangedEventHandler( object sender, ValueEventArgs e); class LongTimeWork
{
// 定义一个事件来提示界面工作的进度
public event ValueChangedEventHandler ValueChanged; // 触发事件的方法
protected void OnValueChanged( ValueEventArgs e)
{
if( this.ValueChanged != null)
{
this.ValueChanged( this, e);
}
} public void LongTimeMethod()
{
for (int i = ; i < ; i++)
{
// 进行工作
System.Threading.Thread.Sleep(); // 触发事件
ValueEventArgs e = new ValueEventArgs() { Value = i+};
this.OnValueChanged(e);
}
}
}
}
WINFORM后台代码
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
} // 进度发生变化之后的回调方法
private void workder_ValueChanged(object sender, Business.ValueEventArgs e)
{
System.Windows.Forms.MethodInvoker invoker = () =>
{
this.progressBar1.Value = e.Value;
}; if (this.progressBar1.InvokeRequired)
{
this.progressBar1.Invoke(invoker);
}
else
{
invoker();
}
} private void button1_Click(object sender, EventArgs e)
{
// 禁用按钮
this.button1.Enabled = false; // 实例化业务对象
LongTime.Business.LongTimeWork workder = new Business.LongTimeWork(); workder.ValueChanged += new Business.ValueChangedEventHandler(workder_ValueChanged); // 使用异步方式调用长时间的方法
Action handler = new Action(workder.LongTimeMethod);
handler.BeginInvoke(
new AsyncCallback(this.AsyncCallback),
handler
);
} // 结束异步操作
private void AsyncCallback(IAsyncResult ar)
{
// 标准的处理步骤
Action handler = ar.AsyncState as Action;
handler.EndInvoke(ar); MessageBox.Show("工作完成！"); System.Windows.Forms.MethodInvoker invoker = () =>
{
// 重新启用按钮
this.button1.Enabled = true;
}; if (this.InvokeRequired)
{
this.Invoke(invoker);
}
else
{
invoker();
}
} }