c# - 如何在 C# Windows 服务应用程序中使用 Win32Api
问题描述
我正在 Visual Studio 中创建一个 Windows 服务应用程序,我想获取当前活动的窗口标题。下面是我尝试过的代码,但函数 GetForegroundWindow() 每次都返回 0。windows服务中使用win32api可以吗?
public partial class My_Service: ServiceBase
{
Timer timer = new Timer();
[DllImport("User32.dll")]
static extern IntPtr GetForegroundWindow();
[DllImport("User32.dll")]
static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);
public My_Service()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
WriteToFile("Service is started at " + DateTime.Now);
timer.Elapsed += new ElapsedEventHandler(OnElapsedTime);
timer.Interval = 10000; //number in milisecinds
timer.Enabled = true;
}
protected override void OnStop()
{
WriteToFile("Service is stopped at " + DateTime.Now);
}
private void OnElapsedTime(object source, ElapsedEventArgs e)
{
string title = GetActivewindow();
WriteToFile("Service is recall at " + title + DateTime.Now);
}
public void WriteToFile(string Message)
{
....
}
public string GetActivewindow()
{
const int nChars = 256;
StringBuilder buff = new StringBuilder(nChars);
string title = "- ";
IntPtr handle;
handle = GetForegroundWindow();
if( GetWindowText(handle,buff,nChars) > 0)
{
title = buff.ToString();
}
return title;
}
}
解决方案
作为评论,也根据文档:关于 Window Stations and Desktops - Window Station and Desktop Creation。
您的服务可能正在运行Service-0x0-3e7$\default
,但您要检索的前台窗口位于交互式窗口站 ( Winsta0\default
)的默认桌面中
交互式窗口站是唯一可以显示用户界面或接收用户输入的窗口站。它分配给交互式用户的登录会话,并包含键盘、鼠标和显示设备。它始终命名为“WinSta0”。所有其他窗口站都是非交互式的,这意味着它们不能显示用户界面或接收用户输入。
这意味着您不能GetForegroundWindow
直接从服务中使用。您可以在其中创建一个子进程Winsta0\default
并重定向其输出。然后调用GetForegroundWindow
子进程并输出。
示例(删除错误检查):
孩子:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
using System.IO;
using System.Threading;
namespace ConsoleApp1
{
class Program
{
[DllImport("User32.dll")]
static extern IntPtr GetForegroundWindow();
[DllImport("User32.dll")]
static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);
static void Main(string[] args)
{
const int nChars = 256;
StringBuilder buff = new StringBuilder(nChars);
string title = "- ";
IntPtr handle;
handle = GetForegroundWindow();
if (GetWindowText(handle, buff, nChars) > 0)
{
title = buff.ToString();
}
Console.WriteLine(title);
return;
}
}
}
服务:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
using System.IO;
using System.Diagnostics.Tracing;
namespace WindowsService3
{
public partial class MyNewService : ServiceBase
{
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
internal struct STARTUPINFO
{
public Int32 cb;
public string lpReserved;
public string lpDesktop;
public string lpTitle;
public Int32 dwX;
public Int32 dwY;
public Int32 dwXSize;
public Int32 dwYSize;
public Int32 dwXCountChars;
public Int32 dwYCountChars;
public Int32 dwFillAttribute;
public Int32 dwFlags;
public Int16 wShowWindow;
public Int16 cbReserved2;
public IntPtr lpReserved2;
public IntPtr hStdInput;
public IntPtr hStdOutput;
public IntPtr hStdError;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
internal struct PROCESS_INFORMATION
{
public IntPtr hProcess;
public IntPtr hThread;
public Int32 dwProcessId;
public Int32 dwThreadId;
}
[StructLayout(LayoutKind.Sequential)]
public struct SECURITY_ATTRIBUTES
{
public int nLength;
public IntPtr lpSecurityDescriptor;
public int bInheritHandle;
}
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool CreateProcessAsUser(
IntPtr hToken,
string lpApplicationName,
string lpCommandLine,
IntPtr lpProcessAttributes,
IntPtr lpThreadAttributes,
bool bInheritHandles,
uint dwCreationFlags,
IntPtr lpEnvironment,
IntPtr lpCurrentDirectory,
ref STARTUPINFO lpStartupInfo,
out PROCESS_INFORMATION lpProcessInformation);
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool CreatePipe(
ref IntPtr hReadPipe,
ref IntPtr hWritePipe,
ref SECURITY_ATTRIBUTES lpPipeAttributes,
uint nSize);
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool ReadFile(
IntPtr hFile,
byte[] lpBuffer,
uint nNumberOfBytesToRead,
out uint lpNumberOfBytesRead,
IntPtr lpOverlapped);
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern uint WTSGetActiveConsoleSessionId();
[DllImport("Wtsapi32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern bool WTSQueryUserToken(UInt32 SessionId, out IntPtr hToken);
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern uint WaitForSingleObject(IntPtr hProcess, uint dwMilliseconds);
public MyNewService()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
System.Diagnostics.Debugger.Launch();
using (StreamWriter sw = File.CreateText("Path\\Log.txt"))
{
IntPtr read = new IntPtr();
IntPtr write = new IntPtr();
IntPtr read2 = new IntPtr();
IntPtr write2 = new IntPtr();
SECURITY_ATTRIBUTES saAttr = new SECURITY_ATTRIBUTES();
saAttr.nLength = Marshal.SizeOf(typeof(SECURITY_ATTRIBUTES));
saAttr.bInheritHandle = 1;
saAttr.lpSecurityDescriptor = IntPtr.Zero;
CreatePipe(ref read, ref write, ref saAttr, 0);
CreatePipe(ref read2, ref write2, ref saAttr, 0);
uint CREATE_NO_WINDOW = 0x08000000;
int STARTF_USESTDHANDLES = 0x00000100;
STARTUPINFO si = new STARTUPINFO();
si.cb = Marshal.SizeOf(typeof(STARTUPINFO));
si.hStdOutput = write;
si.hStdError = write;
si.hStdInput = read2;
si.lpDesktop = "Winsta0\\default";
si.dwFlags = STARTF_USESTDHANDLES;
PROCESS_INFORMATION pi;
IntPtr hToken;
bool err = WTSQueryUserToken(WTSGetActiveConsoleSessionId(), out hToken);
string path = "Path\\ConsoleApp1.exe";
if (CreateProcessAsUser(hToken, path, null, IntPtr.Zero, IntPtr.Zero, true, CREATE_NO_WINDOW, IntPtr.Zero, IntPtr.Zero, ref si, out pi))
{
uint ret = WaitForSingleObject(pi.hProcess, 2000); //wait for the child process exit.
if (ret == 0)
{
byte[] title = new byte[200];
uint reads = 0;
CloseHandle(write);
err = ReadFile(read, title, 200, out reads, IntPtr.Zero);
string result = System.Text.Encoding.UTF8.GetString(title).Replace("\0","").Replace("\r", "").Replace("\n", "");
sw.WriteLine(result);
}
}
CloseHandle(read2);
CloseHandle(write2);
CloseHandle(read);
}
}
protected override void OnStop()
{
}
}
}
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