java - 使用 JNA 和 EnumWindows 的问题

Question

我正在试验 JNA，这是我尝试运行的第一个程序。我从引用资料中复制了它，但是，当我运行它时，他发现了 412 个窗口……而且我很确定我现在没有打开那么多窗口 :) 请有人向我解释程序的行为吗？

import com.sun.jna.Pointer;
import com.sun.jna.win32.StdCallLibrary.StdCallCallback;
import com.sun.jna.Native;
import com.sun.jna.win32.StdCallLibrary;

public class Main {
// Equivalent JNA mappings
    public interface User32 extends StdCallLibrary {
        User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class);

        interface WNDENUMPROC extends StdCallCallback {
            boolean callback(Pointer hWnd, Pointer arg);
        }

        boolean EnumWindows(WNDENUMPROC lpEnumFunc, Pointer arg);
    }

    public static void main(String[] args) {
        User32 user32 = User32.INSTANCE;

        user32.EnumWindows(new User32.WNDENUMPROC() {
            int count;
            public boolean callback(Pointer hWnd, Pointer userData) {
                System.out.println("Found window " + hWnd + ", total " + ++count);
                return true;
            }
        }, null);
    }
}

Answer 1

在 Windows 中，几乎一切都是窗口。以下是您的代码的一些更改，将显示一些窗口标题/文本:

import com.sun.jna.Pointer;
import com.sun.jna.Native;
import com.sun.jna.win32.StdCallLibrary;

public class JNA_Main {
    // Equivalent JNA mappings
    public interface User32 extends StdCallLibrary {
        User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class);

        interface WNDENUMPROC extends StdCallCallback {
            boolean callback(Pointer hWnd, Pointer arg);
        }

        boolean EnumWindows(WNDENUMPROC lpEnumFunc, Pointer arg);

        int GetWindowTextA(Pointer hWnd, byte[] lpString, int nMaxCount);
    }

    public static void main(String[] args) {
        final User32 user32 = User32.INSTANCE;

        user32.EnumWindows(new User32.WNDENUMPROC() {

            int count;

            public boolean callback(Pointer hWnd, Pointer userData) {
                byte[] windowText = new byte[512];
                user32.GetWindowTextA(hWnd, windowText, 512);
                String wText = Native.toString(windowText);
                wText = (wText.isEmpty()) ? "" : "; text: " + wText;
                System.out.println("Found window " + hWnd + ", total " + ++count + wText);
                return true;
            }
        }, null);
    }
}

有什么不明白的请追问。