在Java中获取活动窗口信息

Question

我正在尝试使用Java升级我的应用程序,只有在具有特定名称的进程窗口处于活动状态时才能工作.我发现使用JNI可以实现这一点,但我不知道究竟是怎么做到的.我找不到任何可以解释它的描述或例子.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或其他任何方式 - 我接受任何其他解决方案)？

Answer 1

为自己省点痛苦并使用JNA.您需要为Win32 API 下载 jna.jar和jna -platform.jar.该PInvoke的 wiki和MSDN是找到合适的系统调用是有用的.

无论如何,这里是打印当前活动窗口的标题和过程的代码.

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);
    }
}

Answer 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);
    }
 }