需求是这样，有个程序界面我们需要通过自己的程序持续输入数据，界面如图。

可以获得控件的句柄而用钩子写入值。这里需要用到spy++工具。在VS的工具下有个spy++工具，打开如下图

通过这个工具可以获得窗体的句柄，当然这里获得的句柄只能用于测试，因为.net开发的程序窗体每次打开句柄都会变，都需要重新获得。这个工具的用处在于找一个控件的前一句柄控件和后一句柄控件。

一、引用

//寻找目标进程窗口       
[DllImport("USER32.DLL")]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
[DllImport("USER32.DLL", EntryPoint = "FindWindowEx", SetLastError = true)]
public static extern IntPtr FindWindowEx(IntPtr hwndParent, uint hwndChildAfter,string lpszClass, string lpszWindow);
//设置进程窗口到最前       
[DllImport("USER32.DLL")]
public static extern bool SetForegroundWindow(IntPtr hWnd);
//模拟键盘事件         
[DllImport("USER32.DLL")]
public static extern void keybd_event(Byte bVk, Byte bScan, Int32 dwFlags, Int32 dwExtraInfo);
public delegate bool CallBack(IntPtr hwnd, int lParam);
[DllImport("USER32.DLL")]
public static extern int EnumChildWindows(IntPtr hWndParent, CallBack lpfn, int lParam);
//给CheckBox发送信息
[DllImport("USER32.DLL", EntryPoint = "SendMessage", SetLastError = true, CharSet = CharSet.Auto)]
public static extern int SendMessage(IntPtr hwnd, UInt32 wMsg, int wParam, int lParam);
//给Text发送信息
[DllImport("USER32.DLL", EntryPoint = "SendMessage")]
private static extern int SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, string lParam);
[DllImport("USER32.DLL")]
public static extern IntPtr GetWindow(IntPtr hWnd, int wCmd);

二、方法

公共方法

/// <summary>
/// 查找窗体上控件句柄
/// </summary>
/// <param name="hwnd">父窗体句柄</param>
/// <param name="lpszWindow">控件标题(Text)</param>
/// <param name="bChild">设定是否在子窗体中查找</param>
/// <returns>控件句柄，没找到返回IntPtr.Zero</returns>
private static IntPtr FindWindowEx(IntPtr hwnd, string lpszWindow, bool bChild)
{
    IntPtr iResult = IntPtr.Zero;
    // 首先在父窗体上查找控件
    iResult = FindWindowEx(hwnd, 0, null, lpszWindow);
    // 如果找到直接返回控件句柄
    if (iResult != IntPtr.Zero) return iResult;
    // 如果设定了不在子窗体中查找
    if (!bChild) return iResult;
    // 枚举子窗体，查找控件句柄
    int i = EnumChildWindows(
    hwnd,
    (h, l) =>
    {
        IntPtr f1 = FindWindowEx(h, 0, null, lpszWindow);
        if (f1 == IntPtr.Zero)
            return true;
        else
        {
            iResult = f1;
            return false;
        }
    },
    0);
    // 返回查找结果
    return iResult;
}

/// <summary>
/// 输入回车
/// </summary>
private static void PrintEnter()
{
    keybd_event(Convert.ToByte(13), 0, 0, 0);
    keybd_event(Convert.ToByte(13), 0, 2, 0);
}

获得窗体句柄

IntPtr wcHandle = FindWindow(null, "窗体名称");
if (wcHandle != IntPtr.Zero)
{
    //设置游戏窗口到最前
    SetForegroundWindow(wcHandle);
}

获得有Title的控件句柄

uint BM_GETCHECK = 0xF0;
uint BST_CHECKED = 0xF1;

IntPtr weightIntPtr = FindWindowEx(wcHandle, "输入重量[&H]", true);
if (weightIntPtr != IntPtr.Zero)
{
    //获得Checkbox值
    int i = SendMessage(weightIntPtr, BM_GETCHECK, 0, 0);
    //更改CheckBox值
    SendMessage(weightIntPtr, BST_CHECKED, 1, 0);
}

获得没Title的控件句柄

public enum WindowSearch
{
    GW_HWNDFIRST = 0, //同级别第一个
    GW_HWNDLAST = 1, //同级别最后一个
    GW_HWNDNEXT = 2, //同级别下一个
    GW_HWNDPREV = 3, //同级别上一个
    GW_OWNER = 4, //属主窗口
    GW_CHILD = 5 //子窗口}获取与指定窗口具有指定关系的窗口的句柄 
}
IntPtr waybill = GetWindow(waybillIntPtr, (int)WindowSearch.GW_HWNDNEXT);
SendMessage(waybill, WM_SETTEXT, IntPtr.Zero, waybillValue);

这里完成了我们的需求，改变了窗体中选择框和Text文本框的值。