C# 有记忆功能的地址栏控件
今天在做搜索引擎的资料准备，无意见到了cocosoft的文章，于是,按照原文一步一步，做了下来，运行后，感觉挺不错的，跟我前面写过的c#读取网页有些相识，但多了个地址栏的记忆功能．
本文描述了如何建立一个简单的、常用的用户控件——地址栏。
你只需要输入部分字符，它在其下拉列表框中，就显示出来与你所输入相关的内容(记忆功能)。
如果只要求输入字符串就可以的话。那么，我们可以直接使用TextBox等控件完成输入框。但如果你要让你的输入框有记忆功能的话。那么，我们所需要的就是要求能把以前所输入的内容读取出来。
我们从下面开始讲解如何让我们的地址栏有记忆功能的。
建立自己的地址栏：
首先，我们要分两步走。
第一步，我们首先要明白我们IE地址栏的历史记忆内容是从哪来的。因为只有知道它是从哪来的，我们才能明白我们的数据。
先看一下，IE在regedit(注册表)里面都有些什么内容。因为regeidt是Windows里面一个非常不错的数据库，它可以把整台机子相关的一些东西都存放在里面。
在regedit里面，与IE相关的内容有这些：
我们要的是“Software\Microsoft\Internet Explorer\TypedURLs”的数据。不然，我们写的记忆功能就起不了什么作用了。或者，出现一些其它数据。要知道，在regedit里面保存的数据可都是一些关键数据。如果一不小心被人XX掉的话，那么，L。
OK，现在已经找到我们要的数据是从什么地方来的了。那么，我们就要开始打造我们自己的带记忆功能的地址栏了。
那么，达到这些够了吗？当然，够是够了。但，你不想让你的地址栏功能再强大一点吗？那么，我们写这样的一个类来看看：
1、 新建项目，选择新建类库，名字就顺意了。比如：ControlSet.URLControl。
2、 在资源管理里面添加引用System.Windows.Forms.dll。
3、 然后，在资源管理器里面把Class1.cs改为UnManagedMethods.cs，然后，用下面的代码替换：
using System;using System.Runtime.InteropServices;namespace ControlSet.URLControl
{
[StructLayout(LayoutKind.Sequential)] internal struct Rect
{
public int left; public int top; public int right; public int bottom;
} [StructLayout(LayoutKind.Sequential)] internal struct ComboBoxInfo { public int cbSize; public Rect rcItem; public Rect rcButton; public IntPtr stateButton; public IntPtr hwndCombo; public IntPtr hwndEdit; public IntPtr hwndList; } /// <summary> /// All unmanaged DllImport methods used in this assembly /// </summary> internal class UnManagedMethods { [DllImport("User32.dll")] internal static extern bool GetComboBoxInfo(IntPtr hwndCombo, ref ComboBoxInfo info); [DllImport("Shlwapi.dll")] internal static extern void SHAutoComplete(IntPtr hwnd, IntPtr flags); }
}第二步，我们的地址栏出现了。那么，要用什么做为它的基控件呢？
因为我们要有记忆功能，那么，当然，要有一个能下拉的东西了。什么？ComboBox就是最好的选择。那好，我们开始用ComboBox来构建我们自己的控件。
using System;using Microsoft.Win32;using System.Windows.Forms;namespace ControlSet.URLControl{ /// <summary> /// URLComboBox 的摘要说明。 /// </summary> /// /// <summary> /// A simple enumeration that wraps various auto complete flags of SHAutoComplete. /// See documenation of SHAutoComplete for details /// </summary> [Flags] public enum AutoCompleteFlags : int { /// <summary> /// This includes the File System as well as the rest of the shell (Desktop\My Computer\Control Panel\) /// </summary> FileSystem = 0x00000001, /// <summary> /// URLs in the User's History /// </summary> URLHistory = 0x00000002, /// <summary> /// URLs in the User's Recently Used list. /// </summary> URLMRU = 0x00000004, /// <summary> /// Use the tab to move thru the autocomplete possibilities instead of to the next dialog/window control. /// </summary> UseTab = 0x00000008, /// <summary> /// This includes the File System /// </summary> FileSystemOnly = 0x00000010, /// <summary> /// Same as FileSystemOnly except it only includes directories, UNC servers, and UNC server shares. /// </summary> FileSystemDirs = 0x00000020, /// <summary> /// Ignore the registry default and force the auto suggest feature on. /// </summary> AutoSuggestForceOn = 0x10000000, /// <summary> /// Ignore the registry default and force the auto suggest feature off /// </summary> AutoSuggestForceOff = 0x20000000, /// <summary> /// Ignore the registry default and force the auto append on. /// </summary> AutoAppendForceOn = 0x40000000, /// <summary> /// Ignore the registry default and force auto append off. /// </summary> AutoAppendForceOff = -2147483648 } /// <summary> /// Enumeration for possible types of registry base keys for storing most recntly typed URLs /// </summary> public enum MRUKeyHive : int { /// <summary> /// Value that indicates HKEY_CURRENT_USER should be used for MRUKey property /// </summary> CurrentUser = 1, /// <summary> /// Value that indicates HKEY_LOCAL_MACHINE should be used for MRUKey property /// </summary> LocalMachine = 2, } public class URLComboBox : ComboBox { /// <summary> /// Member variable which stores the autocomplete flags /// </summary> private AutoCompleteFlags _flags = AutoCompleteFlags.FileSystem | AutoCompleteFlags.URLHistory | AutoCompleteFlags.URLMRU; /// <summary> /// Member variable which stores the mru key /// </summary> private string _mruKey = @"Software\Microsoft\Internet Explorer\TypedURLs"; /// <summary> /// Member variable which stores the mru key hive /// </summary> private MRUKeyHive _mruKeyHive = MRUKeyHive.CurrentUser; /// <summary> /// Gets or sets the auto complete flags /// </summary> public AutoCompleteFlags Flags { get { return _flags; } set { _flags = value; } } /// <summary> /// Gets or sets the registry key name where the combo box maintains MRU list. /// </summary> public string MRUKey { get { return _mruKey; } set { _mruKey = value; } } /// <summary> /// Gets or sets the registry key hive for the MRUKey property. /// </summary> public MRUKeyHive MRUKeyHive { get { return _mruKeyHive; } set { _mruKeyHive = value; } } /// <summary> /// Initilaizes a new instance of URLComboBox /// </summary> public URLComboBox() : base() { } /// <summary> /// Gets the registry key where MRU URLs are stored /// </summary> /// <param name="writable">Indicates whether to get the key so that it values written to it</param> /// <returns>RegistryKey object for the MRU registry key or null if none exists</returns> private RegistryKey GetMRUKey(bool writable) { if (_mruKey.Length == 0) return null; RegistryKey ret = null; switch(_mruKeyHive) {
case MRUKeyHive.LocalMachine: ret = Registry.LocalMachine.OpenSubKey(_mruKey, writable); break; case MRUKeyHive.CurrentUser: ret = Registry.CurrentUser.OpenSubKey(_mruKey, writable); break; } return ret; } /// <summary> /// Writes information about any ignored exception to the trace. /// </summary> /// <param name="e">The exception which is being ignored</param> private void TraceIgnoredError(Exception e) { //It's ok if there is any error System.Diagnostics.Trace.WriteLine(e.Message); System.Diagnostics.Trace.WriteLine(e.StackTrace); } /// <summary> /// Utility function to fill the combob box most recently typed URLs read from registry. /// </summary> private void MRUFill() { if (DesignMode) return; RegistryKey mruKey = null; try { int i = 1; string strFormat = "url{0}"; object defaultValue = String.Empty; object url; mruKey = GetMRUKey(false); if (mruKey != null) { while((url = mruKey.GetValue(String.Format(strFormat, i), defaultValue)) != defaultValue) { Items.Add(url); i++; } } } catch(Exception e) { TraceIgnoredError(e); } finally { if (mruKey != null) mruKey.Close(); } } /// <summary> /// Writes the recntly typed URL to the registry if it is not already there /// </summary> /// <param name="e"></param> protected override void OnValidated(System.EventArgs e) { if (DesignMode) return; if ((Text.Length != 0) && (Items.IndexOf(Text) == -1)) { Items.Add(Text); RegistryKey mruKey = null; //Finally add it to the registry try { mruKey = GetMRUKey(true); if (mruKey != null) mruKey.SetValue(String.Format("url{0}", Items.Count), Text); } catch(Exception ex) { TraceIgnoredError(ex); } finally { if (mruKey != null) mruKey.Close(); } } base.OnValidated(e); } /// <summary> /// Finds the handle to the edit control and calls SHAutoComplete on it. /// Also fills the combobox from the values read from the registry /// </summary> /// <param name="e">Ignored</param> protected override void OnHandleCreated(System.EventArgs e) { base.OnHandleCreated(e); if (DesignMode) return; //This is the right place do auto completion ComboBoxInfo info = new ComboBoxInfo(); info.cbSize = System.Runtime.InteropServices.Marshal.SizeOf(info); if (UnManagedMethods.GetComboBoxInfo(Handle, ref info)) { UnManagedMethods.SHAutoComplete(info.hwndEdit, (IntPtr)_flags); } MRUFill(); } }}我们的带记忆功能的地址栏已经构建完成。你可以在菜单【生成(B)】里面，调试生成解决方案。
建立示例程序：
1、 新建项目，选择Windows应用程序，名称：TestrulComboBox。
2、 我们把我们所需要的控件放到工具箱里面。在工具箱上面点右键。添加/移除项。打开Com组件，选择刚才项目生成的ControlSet.URLControl.dll。
3、 把刚才添加到工具箱上面的Microsoft Web 浏览器控件，和ControlSet.URLControl.dll控件，拖放到主窗口上,并进行排列。
4、 添加一个控钮。并在它的事件中输入如下代码：
private void btnSure_Click(object sender, System.EventArgs e) { Cursor currentCursor = Cursor.Current; try { Cursor.Current = Cursors.WaitCursor; object arg1 = 0; object arg2 = ""; object arg3 = ""; object arg4 = ""; axWebBrowser1.Navigate(urlComboBox1.Text,ref arg1,ref arg2, ref arg3, ref arg4); } finally { Cursor.Current = currentCursor; } }
