创建ITaskbarList3实例失败

Question

我正在学习新的 Java FFM API。 在学习过程中，我决定使用Windows SDK来控制

Taskbar

。

界面

ITtaskbarList3

代表

Taskbar

并提供控制它的功能。

我使用

jextract

工具生成必要的类：

jextract --output target/generated-sources/jextract -t "taskbar_test.gen" -l :shell32 -l :Explorerframe -l :ole32 -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\shared" -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\um" -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\km" -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\km\crt" "C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\um\ShObjIdl_core.h"

在下面的代码中，我尝试从

CLSID

获取

IID

和

string

并使用它们来获取

ITaskbarList3

的实例：

package taskbar_test;

import taskbar_test.gen.CLSID;
import taskbar_test.gen.ShObjIdl_core_h;

import java.lang.foreign.Arena;
import java.lang.foreign.MemorySegment;

public class ComStart {

    public static final String GUID_FORMAT = "{%s}";
    
    // CLSID of ITaskbarList3
    public static final String CLSID_CONST = "56FDF344-FD6D-11d0-958A-006097C9A090";
    // IID of ITaskbarList3
    public static final String IID_CONST = "EA1AFB91-9E28-4B86-90E9-9E9F8A5EEFAF";

    public static void main(String[] args) {

            try (var arena = Arena.ofConfined()) {
                // https://learn.microsoft.com/en-us/windows/win32/api/combaseapi/nf-combaseapi-clsidfromstring#remarks
                // The CLSID format is {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}.
                var clsidString = arena.allocateFrom(GUID_FORMAT.formatted(CLSID_CONST));
                var iidString = arena.allocateFrom(GUID_FORMAT.formatted(IID_CONST));
                var clsid = arena.allocate(CLSID.layout());
                var iid = arena.allocate(CLSID.layout());
                var taskbarPtr = arena.allocate(ShObjIdl_core_h.C_POINTER);

                int hr = ShObjIdl_core_h.CoInitializeEx(MemorySegment.NULL, ShObjIdl_core_h.COINIT_MULTITHREADED());
                if (hr != ShObjIdl_core_h.S_OK()) {
                    throw new RuntimeException("CoInitialize failed with error code: " + hr);
                }

                hr = ShObjIdl_core_h.CLSIDFromString(clsidString, clsid);
                if (hr != ShObjIdl_core_h.S_OK()) {
                    throw new RuntimeException("CLSIDFromString failed with error code: " + hr);
                }
                
                hr = ShObjIdl_core_h.IIDFromString(iidString, iid);
                if (hr != ShObjIdl_core_h.S_OK()) {
                    throw new RuntimeException("IIDFromString failed with error code: " + hr);
                }

                hr = ShObjIdl_core_h.CoCreateInstance(clsid, MemorySegment.NULL, ShObjIdl_core_h.CLSCTX_REMOTE_SERVER(), iid, taskbarPtr);
                if (hr != ShObjIdl_core_h.S_OK()) {
                    if (hr == ShObjIdl_core_h.REGDB_E_CLASSNOTREG()) {
                        System.out.println("COM class is not registered!");
                    }
                    throw new RuntimeException("CoCreateInstance failed with error code: " + hr);
                }

            } finally {
                ShObjIdl_core_h.CoUninitialize();
            }
    }

}

我希望获得实例，但我从函数

CLSIDFromString

得到错误，字符串的格式不正确。我不明白为什么，因为格式遵循文档。

代码应该是什么样子才能正确获取实例，以便我可以管理任务栏，即设置进度值。

谢谢你。

Answer 1

您已使用 UTF-8 编码将 String 转换为 MemorySegment，这是

allocateFrom(String)

的默认编码。指定 Windows 宽字符集 UTF_16LE 作为 allocateFrom:

的额外参数

var clsidString = arena.allocateFrom(GUID_FORMAT.formatted(CLSID_CONST), StandardCharsets.UTF_16LE);
var iidString = arena.allocateFrom(GUID_FORMAT.formatted(IID_CONST), StandardCharsets.UTF_16LE);