语法
C++
C#
Visual Basic .NET
返回值
备注
在 Windows 中,之所以有此限制,是因为 Win32 的 LoadLibrary 和 FreeLibrary 函数不是可重入的。
示例
C++(COM)代码
C++(COM)代码
C# 代码
C# 代码
HRESULT __stdcall DeinitializeEngine();
int DeinitializeEngine();
Private Declare Function DeinitializeEngine Lib "FREngine.dll" () As Integer
C++(COM)代码
IEngine* FineReaderEngine = 0;
HMODULE EngineLibraryHandle = 0;
static HRESULT deinitializeEngine()
{
// 释放 Engine 对象
if( FineReaderEngine != 0 ) {
FineReaderEngine->Release();
FineReaderEngine = 0;
}
// 调用 DeinitializeEngine
typedef HRESULT (STDAPICALLTYPE* DeinitializeEngineFunc)();
DeinitializeEngineFunc pDeinitializeEngine =
(DeinitializeEngineFunc)GetProcAddress( EngineLibraryHandle, "DeinitializeEngine" );
if( pDeinitializeEngine == 0 || FAILED( pDeinitializeEngine() ) ) {
setLastErrorInfo( L"无法卸载 FineReader Engine。" );
return E_UNEXPECTED;
}
return S_OK;
}
C# 代码
public class EngineLoader : IDisposable
{
// 卸载 FineReader Engine
public void Dispose()
{
if (engine == null)
{
// 尚未加载 Engine
return;
}
engine = null;
// 在调用 FreeLibrary 之前删除所有对象
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
int hresult = deinitializeEngine();
hresult = dllCanUnloadNow();
if (hresult == 0)
{
FreeLibrary(dllHandle);
}
dllHandle = IntPtr.Zero;
initializeEngine = null;
deinitializeEngine = null;
dllCanUnloadNow = null;
// 清理后抛出异常
Marshal.ThrowExceptionForHR(hresult);
}
// Kernel32.dll 函数
[DllImport("kernel32.dll")]
private static extern IntPtr LoadLibraryEx(string dllToLoad, IntPtr reserved, uint flags);
private const uint LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008;
[DllImport("kernel32.dll")]
private static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName);
[DllImport("kernel32.dll")]
private static extern bool FreeLibrary(IntPtr hModule);
// FREngine.dll 函数
[UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Unicode)]
private delegate int InitializeEngine( string customerProjectId, string LicensePath, string LicensePassword, , , , ref FREngine.IEngine engine);
[UnmanagedFunctionPointer(CallingConvention.StdCall)]
private delegate int DeinitializeEngine();
[UnmanagedFunctionPointer(CallingConvention.StdCall)]
private delegate int DllCanUnloadNow();
// 私有变量
private FREngine.IEngine engine = null;
// FREngine.dll 的 Handle
private IntPtr dllHandle = IntPtr.Zero;
private InitializeEngine initializeEngine = null;
private DeinitializeEngine deinitializeEngine = null;
private DllCanUnloadNow dllCanUnloadNow = null;
}
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