C# 如何用获取某个应用程序里面的文本框的句柄,并且获取文本框里面的值?

我是要拿到那个程序里面文本框的句柄.

const int HWND_TOPMOST = -1;
const int SWP_SHOWWINDOW = 40;
const int WM_GETTEXT = 0x000D;
private void Form1_Load(object sender, System.EventArgs e)
{
IntPtr ab = new IntPtr();
StringBuilder className = new StringBuilder(256);
IntPtr ip = User32API.FindWindow("Notepad", "Raybelly.txt - 记事本");
IntPtr b = User32API.FindWindowEx(ip, ab, "Edit", null);
//User32API.GetWindowText(b, className, className.Capacity);
//MessageBox.Show(className.ToString());

string w = "";
IntPtr ptr = Marshal.StringToHGlobalAnsi(w);
if (User32API.SendMessage(b, WM_GETTEXT, 100000, ptr))
MessageBox.Show(Marshal.PtrToStringAnsi(ptr));

}

参照以上资材（网上下载的）编写了我自己的程序，运行过程中发现功能没有问题，但是经常死机，卡死。

应该反复寻找，找到了额问题点的所在

string w="" ; 申请的是空字符串，而 if (User32API.SendMessage(b, WM_GETTEXT, 100000, ptr))  使用了100000个字符串。

运行一次两次没有问题，如果经常使用 会出现 卡死，死机的问题发生

解决办法 string w="" ; 变更为 string  w=new string(new char[100000]);

这样就解决问题了

句柄太消耗CPU资源了

以下是我优化后直接使用StringBuilder 来接收数据

using System.Runtime.InteropServices;

 [DllImport("user32.dll", EntryPoint = "SendMessage")]
 private static extern void SendMessage(IntPtr hwnd, int wMsg, int wParam, StringBuilder lParam);

// rfptr为主菜单的句柄

rfptr = FindWindow(null, "要寻找的标题名称");

//child_2为文本框的 句柄

child_2 = FindWindowEx(rfptr, child_two, "要寻找的类名称");

StringBuilder strbu = new StringBuilder(102);
SendMessage(child_2, 0x0d, 100, strbu);

//label1.text输出找到的文档

label1.text=strbu.tostring();

面是转载自：http://www.cnblogs.com/me-sa/articles/669402.html

SendMessage是一个在user32.dll中声明的API函数，在C#中导入如下：

using System.Runtime.InteropServices;[DllImport("user32.dll", EntryPoint="SendMessageA")]public static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);

本文描述其参数 lParam 的用法，主要是数据类型之间的转化。

● 一种最简单的处理方式是声明多个SendMessage函数(overload)，用所需的数据类型直接替换IntPtr。例如：

//声明:[DllImport("user32.dll", EntryPoint="SendMessageA")]private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, string lParam);[DllImport("user32.dll", EntryPoint="SendMessageA")]private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, ref Rectangle lParam);//调用:string s = "hello, floodzhu";SendMessage(this.textBox1.Handle, WM_SETTEXT, IntPtr.Zero, s);Rectangle rect = new Rectangle();SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, ref rect);

● 对要求返回字符串的类型（out string）可以用 StringBuilder 代替，此时不需要 out/ref。例如：

[DllImport("user32.dll", EntryPoint="SendMessageA")]private static extern int SendMessage (IntPtr hwnd, int wMsg, int wParam, StringBuilder lParam);private void button1_Click(object sender, System.EventArgs e){ const int buffer_size = 1024; StringBuilder buffer = new StringBuilder(buffer_size); SendMessage(this.textBox1.Handle, WM_GETTEXT, buffer_size, buffer); //MessageBox.Show(buffer.ToString());}

● 如果想用 InPtr 类型统一处理的话，可以借助于 Marshal 或者 GCHandle 的相关方法。例如：

[DllImport("user32.dll", EntryPoint="SendMessageA")]private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);private void button2_Click(object sender, System.EventArgs e){ Rectangle rect = new Rectangle(); IntPtr buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Rectangle))); Marshal.StructureToPtr(rect, buffer ,true); SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, buffer); rect = (Rectangle)Marshal.PtrToStructure(buffer, typeof(Rectangle)); Marshal.FreeHGlobal(buffer);}

或者

private void button2_Click(object sender, System.EventArgs e){ Rectangle rect = new Rectangle(); GCHandle gch = GCHandle.Alloc(rect); SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, (IntPtr)gch); rect = (Rectangle)Marshal.PtrToStructure((IntPtr)gch, typeof(Rectangle)); gch.Free();}