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，问题是可见的(64位虚拟机不可见)。
对于结构，上面提到的函数假定它们通过引用传递(指向结构的指针)，因此函数返回Native.POINTER_SIZE的值。 在64位虚拟机上，运气匹配POINT结构的大小。 在32位VM上， Native.POINTER_SIZE是4字节，因此只能保存结果结构的一部分。
最相关的部分：要确定JNA中结构的大小，请使用Structure＃size函数。 在这种情况下，使用ReadProcessMemory的最终参数也很有帮助。 该函数返回读取的字节数并显示差异(4对8)。
进一步的评论：记得释放你分配的内存，并关闭收到的进程句柄。
这是完整的可运行样本(仅缺少导入，使用JNA 5.2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);
}
}
