Java JNA 获取桌面项位置

Question

Goal

获取桌面项目/图标的桌面坐标。

尝试

我已获得 SysListView32 窗口句柄，其中包含使用以下方法的桌面图标：

HWND hWnd_Progman = User32.INSTANCE.FindWindow("Progman", "Program Manager");
HWND hWnd_SHELLDLL_DefView = User32.INSTANCE.FindWindowEx(hWnd_Progman, null, "SHELLDLL_DefView", null);
HWND hWnd_SysListView32 = User32.INSTANCE.FindWindowEx(hWnd_SHELLDLL_DefView, null, "SysListView32", "FolderView");

我已获得桌面项目计数：

LRESULT result = User32.INSTANCE.SendMessage(hWnd_SysListView32, LVM_GETITEMCOUNT, new WPARAM(), new LPARAM());
long desktopIconCount = result.longValue();

我已经设置了一个桌面项目位置(验证 SysListView32 是否是桌面项目的正确列表视图)。传递的 x 和 y 坐标对应于从最左侧显示器的左上角到桌面项目的左上角的偏移量。法典：

int itemIndex = 0; // Allows 0 to desktopIconCount - 1.
int x = ...;
int y = ...;
LRESULT res = User32.INSTANCE.SendMessage(hWnd_SysListView32, LVM_SETITEMPOSITION, new WPARAM(itemIndex), new LPARAM((x & 0xFFFF) | (y << 16)));

现在，要获得桌面项目位置，需要将LVM_GETITEMPOSITION发送到 SysListView32，并包含一个指向可以写入位置的地址的指针。但是，此指针必须是属于 SysListView32 的进程内存中的有效地址。所以我试图做的是：

• 获取属于 SysListView32 的进程。
• 在该进程中分配内存。
• 在此内存中写入一个POINT对象(用于项目位置)。
• 将LVM_GETITEMPOSITION发送到 SysListView32，并带有指向此已分配内存的指针。
• 从内存中读取此POINT对象。此时，进程应已将桌面项目位置写入其中。

我已经用以下代码尝试过这个：

// Get the SysListView32 process handle.
IntByReference processIdRef = new IntByReference();
User32.INSTANCE.GetWindowThreadProcessId(hWnd_SysListView32, processIdRef);
HANDLE procHandle = Kernel32.INSTANCE.OpenProcess(
Kernel32.PROCESS_VM_OPERATION | Kernel32.PROCESS_VM_WRITE | Kernel32.PROCESS_VM_READ,
false, processIdRef.getValue());
// Allocate memory in the SysView32 process.
int pointSize = Native.getNativeSize(POINT.class)); // 8 bytes.
LPVOID pMem = MyKernel32.INSTANCE.VirtualAllocEx(procHandle, new LPVOID(), new SIZE_T(pointSize),
MyKernel32.MEM_COMMIT, MyKernel32.PAGE_READWRITE);
// Put some POINT-sized object in the process its memory.
boolean success = Kernel32.INSTANCE.WriteProcessMemory(
procHandle, pMem.getPointer(), pMem.getPointer(), pointSize, null);
if(!success) {
System.out.println("Write error = " + Kernel32.INSTANCE.GetLastError());
System.exit(1);
}
// Send the LVM_GETITEMPOSITION message to the SysListView32.
int itemIndex = 0; // Allows 0 to desktopIconCount - 1.
LRESULT res = MyUser32.INSTANCE.SendMessage(
hWnd_SysListView32, LVM_GETITEMPOSITION, new WPARAM(itemIndex), pMem.getPointer());
System.out.println("Message result = " + res.longValue());
// Read the earlier POINT-sized written memory.
POINT point = new POINT();
success = Kernel32.INSTANCE.ReadProcessMemory(
procHandle, pMem.getPointer(), point.getPointer(), pointSize, null);
if(!success) {
System.out.println("Read error = " + Kernel32.INSTANCE.GetLastError());
System.exit(1);
}
System.out.println("Point found: x=" + pos.x + ", y=" + pos.y);

在这里，MyUser32创建如下：

interface MyUser32 extends User32 {
static MyUser32 INSTANCE =
(MyUser32) Native.load("user32", MyUser32.class, W32APIOptions.DEFAULT_OPTIONS);
LRESULT SendMessage(HWND hWnd, int msg, WPARAM wParam, Pointer pointer);
}

MyKernel32按如下方式创建：

interface MyKernel32 extends Kernel32 {
static final MyKernel32 INSTANCE =
(MyKernel32) Native.load("kernel32", MyKernel32.class, W32APIOptions.DEFAULT_OPTIONS);
static int MEM_COMMIT = 0x1000;
static int PAGE_READWRITE = 0x04;
LPVOID VirtualAllocEx(HANDLE hProcess, LPVOID lpAddress, SIZE_T dwSize, int flAllocationType, int flProtect);
}

为了完成，使用以下附加静态值：

static final int LVM_FIRST = 0x1000;
static final int LVM_GETITEMCOUNT = LVM_FIRST + 4;
static final int LVM_SETITEMPOSITION = LVM_FIRST + 15;
static final int LVM_GETITEMPOSITION = LVM_FIRST + 16;

问题

WriteProcessMemory调用经常失败，错误代码为 299ERROR_PARTIAL_COPY，即使没有失败，返回的 POINT 也始终为 (0,0)。我希望问题出在MyUser32或MyKernel32中的SendMessage/VirtualAllocEx方法声明中，或者因为我没有正确理解将哪个对象/指针传递给VirtualAllocEx或WriteProcessMemory。

我做了很多研究，并弄清楚了它在 C/C++ 中应该如何工作，但我找不到任何使用 JNA 的工作代码示例。

感谢您表现出兴趣并试图提供帮助，如果您一直通过我的信息。

Answer 1

问题是com.sun.jna.Native.getNativeSize(Class)不是在这种情况下使用的正确函数。使用 32 位 JVM 时，该问题是可见的(在 64 位 VM 中不可见)。

对于结构，上述函数假定它们是通过引用(指向结构的指针)传递的，因此函数返回Native.POINTER_SIZE的值。在 64 位 VM 上，这幸运地匹配了 POINT结构的大小。在 32 位 VM 上，Native.POINTER_SIZE是 4 字节，因此只能保存部分结果结构。

最相关的部分：要在 JNA 中确定结构的大小，请使用结构#大小函数。在这种情况下，使用ReadProcessMemory的最后一个参数也很有帮助。该函数返回读取的字节数并显示差异(4 与 8)。

进一步评论：请记住释放您分配的内存，并关闭进程句柄以接收。

以下是完整的可运行示例(仅缺少导入，使用 JNA 5.2 进行测试)：

public class Test {
private interface Kernel32 extends com.sun.jna.platform.win32.Kernel32 {
Kernel32 INSTANCE = Native.load("kernel32", Kernel32.class, W32APIOptions.DEFAULT_OPTIONS);
public Pointer VirtualAllocEx(HANDLE hProcess, Pointer lpAddress, SIZE_T dwSize, int flAllocationType, int flProtect);
public boolean VirtualFreeEx(HANDLE hProcess, Pointer lpAddress, SIZE_T dwSize, int dwFreeType);
int MEM_COMMIT = 0x00001000;
int MEM_RESERVE = 0x00002000;
int MEM_RESET = 0x00080000;
int MEM_RESET_UNDO = 0x1000000;
int MEM_LARGE_PAGES = 0x20000000;
int MEM_PHYSICAL = 0x00400000;
int MEM_TOP_DOWN = 0x00100000;
int MEM_COALESCE_PLACEHOLDERS = 0x00000001;
int MEM_PRESERVE_PLACEHOLDER = 0x00000002;
int MEM_DECOMMIT = 0x4000;
int MEM_RELEASE = 0x8000;
}
private static final int LVM_FIRST = 0x1000;
private static final int LVM_GETITEMCOUNT = LVM_FIRST + 4;
private static final int LVM_GETITEMPOSITION = LVM_FIRST + 16;
public static void main(String[] args) throws IOException, InterruptedException {
// Find the HWND for the "desktop" list view
HWND hWnd_Progman = User32.INSTANCE.FindWindow("Progman", "Program Manager");
HWND hWnd_SHELLDLL_DefView = User32.INSTANCE.FindWindowEx(hWnd_Progman, null, "SHELLDLL_DefView", null);
HWND hWnd_SysListView32 = User32.INSTANCE.FindWindowEx(hWnd_SHELLDLL_DefView, null, "SysListView32", "FolderView");
// Fetch the icon count
int itemCount = User32.INSTANCE.SendMessage(hWnd_SysListView32, LVM_GETITEMCOUNT, new WPARAM(), new LPARAM()).intValue();
System.out.println("Desktop Icons: " + itemCount);
// Get the SysListView32 process handle.
IntByReference processIdRef = new IntByReference();
User32.INSTANCE.GetWindowThreadProcessId(hWnd_SysListView32, processIdRef);
HANDLE procHandle = Kernel32.INSTANCE.OpenProcess(
Kernel32.PROCESS_VM_OPERATION | Kernel32.PROCESS_VM_WRITE | Kernel32.PROCESS_VM_READ,
false, processIdRef.getValue());
// Allocate memory in the SysView32 process.
int pointSize = new POINT().size(); // 8 bytes.
Pointer pMem = Kernel32.INSTANCE.VirtualAllocEx(procHandle, null, new SIZE_T(pointSize),
Kernel32.MEM_COMMIT, Kernel32.PAGE_READWRITE);
for (int i = 0; i < itemCount; i++) {
// Send the LVM_GETITEMPOSITION message to the SysListView32.
LRESULT res = User32.INSTANCE.SendMessage(
hWnd_SysListView32, LVM_GETITEMPOSITION, new WPARAM(i), new LPARAM(Pointer.nativeValue(pMem)));
if(res.intValue() != 1) {
throw new IllegalStateException("Message sending failed");
}
// Read the earlier POINT-sized written memory.
POINT point = new POINT();
IntByReference read = new IntByReference();
boolean success = Kernel32.INSTANCE.ReadProcessMemory(
procHandle, pMem, point.getPointer(), pointSize, read);
if (!success) {
System.out.println("Read error = " + Kernel32.INSTANCE.GetLastError());
System.exit(1);
}
point.read();
System.out.println("Point found: x=" + point.x + ", y=" + point.y);
}
// Release allocated memory
Kernel32.INSTANCE.VirtualFreeEx(procHandle, pMem, new SIZE_T(0), Kernel32.MEM_RELEASE);
// Close Process Handle
Kernel32.INSTANCE.CloseHandle(procHandle);
}
}