（一）linux下脚本:

#!/bin/bash
#方法一
#xprop -root | grep "_NET_ACTIVE_WINDOW(WINDOW)"| cut -d ' ' -f 5
#方法二
# xwininfo -name ShowAnimationProject | grep "Window id"| cut -d " " -f 4


#方法三
#!/bin/sh

# findpid=$1
# 
# known_windows=$(xwininfo -root -children|sed -e 's/^ *//'|grep -E "^0x"|awk '{ print $1 }')
# 
# for id in ${known_windows}
# do
#     xp=$(xprop -id $id _NET_WM_PID)
#     if test $? -eq 0; then
#         pid=$(xprop -id $id _NET_WM_PID|cut -d'=' -f2|tr -d ' ')
# 
#         if test "x${pid}" = x${findpid}
#         then
#             #echo "Windows Id: $id"
#             echo "$id"
#         fi
#     fi
# done


#@not used

（二）通过代码方式获取

#ifndef WINDOWIDUTIL_H
#define WINDOWIDUTIL_H


#include<QDebug>



// win
#ifdef Q_OS_WIN

#include <windows.h>


typedef struct
{
    HWND hWnd;
    DWORD dwPid;
}WNDINFO;



BOOL
CALLBACK EnumWindowsProc(HWND hWnd, LPARAM lParam)
{
    WNDINFO* pInfo = (WNDINFO*)lParam;
    DWORD dwProcessId = 0;
    GetWindowThreadProcessId(hWnd, &dwProcessId);

    if(dwProcessId == pInfo->dwPid)
    {
     pInfo->hWnd = hWnd;
     return FALSE;
    }
    return TRUE;
}



WId
get_win_id_from_pid(DWORD dwProcessId)
{
    WNDINFO info = {0};
    info.hWnd = NULL;
    info.dwPid = dwProcessId;
    EnumWindows(EnumWindowsProc, (LPARAM)&info);
    return (WId)info.hWnd;
}



#else // linux


#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <iostream>
#include <list>
#include <stdlib.h>




class WindowsMatchingPid
{
public:
    WindowsMatchingPid(Display *display, Window wRoot, unsigned long pid)
        : _display(display),
          _pid(pid)
    {
        // Get the PID property atom.
        _atomPID = XInternAtom(display, "_NET_WM_PID", True);
        if(_atomPID == None)
        {
            std::cout << "No such atom" << std::endl;
            return;
        }

        search(wRoot);
    }

    const std::list<Window> &result() const { return _result; }

private:
    unsigned long  _pid;
    Atom           _atomPID;
    Display       *_display;
    std::list<Window>   _result;

    void
    search(Window w)
    {
        // Get the PID for the current Window.
        Atom           type;
        int            format;
        unsigned long  nItems;
        unsigned long  bytesAfter;
        unsigned char *propPID = 0;
        if(Success == XGetWindowProperty(
                    _display,
                    w,
                    _atomPID,
                    0,
                    1,
                    False,
                    XA_CARDINAL,
                    &type,
                    &format,
                    &nItems,
                    &bytesAfter,
                    &propPID))
        {
            if(propPID != 0)
            {
                // If the PID matches, add this window to the result set.
                if(_pid == *((unsigned long *)propPID))
                {
                    _result.push_back(w);
                }

                XFree(propPID);
            }
        }

        // Recurse into child windows.
        Window    wRoot;
        Window    wParent;
        Window   *wChild;
        unsigned  nChildren;
        if(0 != XQueryTree(_display, w, &wRoot, &wParent, &wChild, &nChildren))
        {
            for(unsigned i = 0; i < nChildren; i++)
                search(wChild[i]);
        }

        //XFree(propPID);
    }
};


unsigned long
get_win_id_from_pid(qint64 pid)
{
    //std::cout << "Searching for windows associated with PID " << pid << std::endl;

    // Start with the root window.
    Display *display = XOpenDisplay(0);

    WindowsMatchingPid match(display, XDefaultRootWindow(display), pid);

    // Print the result.
    const std::list<Window> &result = match.result();

    long win_id = 0;
    for(std::list<Window>::const_iterator pos = result.begin(); pos != result.end(); pos++)
    {
        std::cout << "Window #" << (unsigned long)(*pos) << std::endl;
        win_id = (unsigned long)(*pos);
    }

    return win_id;
}


#endif

#endif // WINDOWIDUTIL_H