详解MessageBox.doc

首先，介绍一下MessageBox.Show（）参数：/提示框显示的按钮public enum MessageBoxButtons OK = 0x00000000, OKCancel = 0x00000001, AbortRetryIgnore = 0x00000002, YesNoCancel = 0x00000003, YesNo = 0x00000004, RetryCancel = 0x00000005 提示框提示的图标public enum MessageBoxIcon None = 0, Hand = 0x00000010, Question = 0x00000020, Exclamation = 0x00000030, Asterisk = 0x00000040, Stop = Hand, Error = Hand, Warning = Exclamation, Information = Asterisk, 提示框默认焦点在第几个按钮上public enum MessageBoxDefaultButton Button1 = 0x00000000, Button2 = 0x00000100, Button3 = 0x00000200,/按钮的显示方式public enum MessageBoxOptions ServiceNotification = 0x00200000, DefaultDesktopOnly = 0x00020000, RightAlign = 0x00080000, RtlReading = 0x00100000,以上这几个枚举是MessageBox最终呈现的效果的设置项，这只是.NET平台提供的设置项，实际上MessageBox显示的样式设置有更多，具体的可以参考windowsAPI MessageBox方法。 具体每个枚举值的意义，在VS中都有说明，这里不在赘述。 接下来，我们要介绍MessageBox这个类里边所有的静态方法： public static DialogResult Show(string text); public static DialogResult Show(IWin32Window owner, string text); public static DialogResult Show(string text, string caption); public static DialogResult Show(IWin32Window owner, string text, string caption); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, bool displayHelpButton); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath, HelpNavigator navigator); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath, string keyword); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath, HelpNavigator navigator); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath, string keyword); public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath, HelpNavigator navigator, object param); public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, string helpFilePath, HelpNavigator navigator, object param);虽然MessageBox的静态方法有20个之多，但是其实每个方法在内部调用的都是ShowCore方法：private static DialogResult ShowCore(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, bool showHelp) 也就是说，其实这个方法是实现消息框的关键，为了更好的理解.NET实现的原理，我把这个方法基本用C#的格式重新写了一遍，代码如下：using System;using System.ComponentModel;using System.Runtime.InteropServices;using System.Security;using System.Security.Permissions;using System.Windows.Forms;namespace WindowsFormsApplication1 class MessageBoxTest DllImport(user32.dll) public static extern IntPtr GetActiveWindow(); DllImport(kernel32.dll, CharSet = CharSet.Auto) public static extern IntPtr GetModuleHandle(string modName); DllImport(kernel32.dll, CharSet = CharSet.Auto) public static extern IntPtr LoadLibrary(string libname); DllImport(user32.dll, CharSet = CharSet.Auto) public static extern int MessageBox(IntPtr hWnd, string text, string caption, uint type); DllImport(user32.dll, CharSet = CharSet.Auto) public static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, int lParam); private const int HELP_BUTTON = 0x00004000; private const int WM_SETFOCUS = 0x0007;internal static DialogResult MessageBoxShow(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options, bool showHelp) if (buttons MessageBoxButtons.RetryCancel) throw new InvalidEnumArgumentException(buttons, (int)buttons, typeof(MessageBoxButtons); if (icon MessageBoxIcon.Asterisk) throw new InvalidEnumArgumentException(icon, (int)icon, typeof(MessageBoxIcon); if (defaultButton MessageBoxDefaultButton.Button3) throw new InvalidEnumArgumentException(defaultButton, (int)defaultButton, typeof(MessageBoxDefaultButton); /options即不包含MessageBoxOptions.ServiceNotification也不包含MessageBoxOptions.DefaultDesktopOnly /或者当前进程在用户交互模式中运行 if (options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly) = 0 & !SystemInformation.UserInteractive) throw new InvalidOperationException(); /options包含MessageBoxOptions.ServiceNotification或者包含MessageBoxOptions.DefaultDesktopOnly /但是owner不为空 if (owner != null & (options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly) != 0) throw new ArgumentException(options); /options包含MessageBoxOptions.ServiceNotification或者包含MessageBoxOptions.DefaultDesktopOnly /但是showHelp位true if (showHelp & (options & (MessageBoxOptions.ServiceNotification | MessageBoxOptions.DefaultDesktopOnly) != 0) throw new ArgumentException(options); /options包含MessageBoxOptions.ServiceNotification或者包含MessageBoxOptions.DefaultDesktopOnly if (options & (MessageBoxOptions.RightAlign | MessageBoxOptions.RtlReading) != 0) CodeAccessPermission permission = new SecurityPermission(SecurityPermissionFlag.UnmanagedCode); permission.Demand(); CodeAccessPermission safePermission = new UIPermission(UIPermissionWindow.SafeSubWindows); safePermission.Demand(); uintstyle = (showHelp) ? (uint)HELP_BUTTON :0; style|= (uint)buttons | (uint)icon | (uint)defaultButton | (uint)options; IntPtr handle = IntPtr.Zero; if(owner =null) handle=GetActiveWindow(); else Control control = ownerasControl; handle= control !=null? control.Handle : owner.Handle; IntPtr userCookie = IntPtr.Zero; if (GetModuleHandle(shell32.dll) = IntPtr.Zero & LoadLibrary(shell32.dll) = IntPtr.Zero) int lastWin32Error = Marshal.Get