在 Java 中获取活动窗口信息

java java-native-interface jna

2022-09-01 10:20:00

我正在尝试将Java中的应用程序升级到仅在具有特定名称的进程窗口处于活动状态时才工作。我发现通过使用JNI可以做到这一点，但我不知道该怎么做。我只是找不到任何描述或例子来解释它。我的问题是 - 如何在Windows中获取当前活动窗口的进程名称（通过JNI或其他任何内容 - 我接受任何其他解决方案）？

答案 1

省去一些痛苦，使用JNA。您需要下载 win32 API 的 jna.jar 和 jna-platform.jar。pinvoke wiki 和 MSDN 对于查找正确的系统调用非常有用。

无论如何，这是用于打印当前活动窗口的标题和进程的代码。

import static enumeration.EnumerateWindows.Kernel32.*;
import static enumeration.EnumerateWindows.Psapi.*;
import static enumeration.EnumerateWindows.User32DLL.*;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.ptr.PointerByReference;

public class EnumerateWindows {
    private static final int MAX_TITLE_LENGTH = 1024;

    public static void main(String[] args) throws Exception {
        char[] buffer = new char[MAX_TITLE_LENGTH * 2];
        GetWindowTextW(GetForegroundWindow(), buffer, MAX_TITLE_LENGTH);
        System.out.println("Active window title: " + Native.toString(buffer));

        PointerByReference pointer = new PointerByReference();
        GetWindowThreadProcessId(GetForegroundWindow(), pointer);
        Pointer process = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, false, pointer.getValue());
        GetModuleBaseNameW(process, null, buffer, MAX_TITLE_LENGTH);
        System.out.println("Active window process: " + Native.toString(buffer));
    }

    static class Psapi {
        static { Native.register("psapi"); }
        public static native int GetModuleBaseNameW(Pointer hProcess, Pointer hmodule, char[] lpBaseName, int size);
    }

    static class Kernel32 {
        static { Native.register("kernel32"); }
        public static int PROCESS_QUERY_INFORMATION = 0x0400;
        public static int PROCESS_VM_READ = 0x0010;
        public static native int GetLastError();
        public static native Pointer OpenProcess(int dwDesiredAccess, boolean bInheritHandle, Pointer pointer);
    }

    static class User32DLL {
        static { Native.register("user32"); }
        public static native int GetWindowThreadProcessId(HWND hWnd, PointerByReference pref);
        public static native HWND GetForegroundWindow();
        public static native int GetWindowTextW(HWND hWnd, char[] lpString, int nMaxCount);
    }
}

答案 2

此代码适用于 JNA 4.0

import com.sun.jna.Native;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinDef.RECT;

// see http://java-native-access.github.io/jna/4.0/javadoc/

public class EnumerateWindows {
    private static final int MAX_TITLE_LENGTH = 1024;

    public static void main(String[] args) throws Exception {
        char[] buffer = new char[MAX_TITLE_LENGTH * 2];
        HWND hwnd = User32.INSTANCE.GetForegroundWindow();
        User32.INSTANCE.GetWindowText(hwnd, buffer, MAX_TITLE_LENGTH);
        System.out.println("Active window title: " + Native.toString(buffer));
        RECT rect = new RECT();
        User32.INSTANCE.GetWindowRect(hwnd, rect);
        System.out.println("rect = " + rect);
    }
 }