分享一個多線程委派的代碼
一般我們在實作多線程存取主線程控制項屬性時，必須以委派方式來存取，否則就有可能會出現 InvalidOperationException 例外，一般初學者總會犯這個錯誤，大都不知道需要委派的動作，總是在子線程用一行 textBox1.Text = "aaaaa" 就想改變控制項的屬性，卻換來 InvalidOperationException 的錯誤，而在一般情況下委派的動作總不會像 textBox1.Text = "aaaaa" 短短一行就這麼直覺的解決問題，總覺得委派代碼實在麻煩。如果你運作的環境是 .net framework 3.5(含以上)，又覺得委派的代碼總是惹人厭的話，下面的代碼或許幫得上你解決惱人的委派問題，至少幫了我很多，分享給大家，以下是實例。
首先定義一個類別，來當然是 Control Class 擴充方法類別。
public static class ExtensionControl{ public static object GetPropertySafe(this Control control, string propertyName) { object returnValue = null; Action func = () => { Type type = control.GetType(); returnValue = type.InvokeMember(propertyName, BindingFlags.GetProperty, null, control, null); }; if (control.InvokeRequired) { control.Invoke(func); } else { func(); } return returnValue; } public static object SetPropertySafe(this Control control, string propertyName, object value) { object returnValue = null; Action func = () => { Type type = control.GetType(); returnValue = type.InvokeMember(propertyName, BindingFlags.SetProperty, null, control, new object[] { value }); }; if (control.InvokeRequired) { control.Invoke(func); } else { func(); } return returnValue; } public static object GetPropertySafe(this ToolStripMenuItem control, string propertyName) { object returnValue = null; Control owner = control.Owner; Action func = () => { Type type = control.GetType(); returnValue = type.InvokeMember(propertyName, BindingFlags.GetProperty, null, control, null); }; if (owner.InvokeRequired) { owner.Invoke(func); } else { func(); } return returnValue; } public static object SetPropertySafe(this ToolStripMenuItem control, string propertyName, object value) { object returnValue = null; Control owner = control.Owner; Action func = () => { Type type = control.GetType(); returnValue = type.InvokeMember(propertyName, BindingFlags.SetProperty, null, control, new object[] { value }); }; if (owner.InvokeRequired) { owner.Invoke(func); } else { func(); } return returnValue; } public static object InvokeMethodSafe(this Control control, string methodName, params object[] args) { object returnValue = null; if (args == null) { args = new object[1]; args[0] = null; } else if (args != null && args.Length == 0) { args = null; } Action func = () => { Type type = control.GetType(); returnValue = type.InvokeMember(methodName, BindingFlags.InvokeMethod, null, control, args); }; if (control.InvokeRequired) { control.Invoke(func); } else { func(); } return returnValue; } public static object InvokeMethodSafe(this ToolStripMenuItem control, string methodName, params object[] args) { object returnValue = null; if (args == null) { args = new object[1]; args[0] = null; } else if (args != null && args.Length == 0) { args = null; } Control owner = control.Owner; Action func = () => { Type type = control.GetType(); returnValue = type.InvokeMember(methodName, BindingFlags.InvokeMethod, null, control, args); }; if (owner.InvokeRequired) { owner.Invoke(func); } else { func(); } return returnValue; }}
namespace WindowsFormsApplication1{ public partial class MainForm : Form { public MainForm() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { Thread thread = new Thread( ThreadStart => { //this.textBox1.Text = "Thread Edit"; //將上方會產生 InvalidOperationException 的代碼註解，改以下方代碼 this.textBox1.SetPropertySafe("Text", "ThreadEdit"); } ); thread.IsBackground = true; thread.Start(); } }}