在VS2008下用ACE创建及使用DLL（动态链接库）

在VS2008下用ACE创建及使用DLL（动态链接库）

下面是 ACE-6.0.0 提供的创建及使用DLL的实例，代码所在目录：\ACE-6.0.0\ACE_wrappers\examples\Export 。

DLL的代码：

1. dll.h 文件

// $Id: dll.h 80826 2008-03-04 14:51:23Z wotte $

// To use the export macros with a DLL, a file will need to be
// created (see ACE_wrapper/bin/generate_export_file.pl) and
// included.  This file defines Test_Export (and the
// TEST_SINGLETON_* macros).
#include "test_export.h"

#include "ace/Singleton.h"
#include "ace/Null_Mutex.h"

#define RETVAL 42

// To expose a function outside of a DLL, use the *_Export
// at the beginning of the function declaration.

Test_Export int test_function ();

// To expose data, put use the *Export at the beginning
// of the variable declaration.  The extern is required when
// building static libraries.

extern Test_Export int test_variable;

// To expose a class, put the *_Export between "class"
// and the class name.

class Test_Export test_class
{
public:
int method ();
};

// ACE_Singleton and its relatives are special cases.  The problem is
// that ACE_Singleton is a template.  If the singleton is used in both
// the DLL and the executable linking the DLL, then two instances of
// the singleton will be used (which defeats the purpose of a Singleton).
//
// This occurs because the ACE_Singleton template is expanded in both
// places because Visual C++ and Borland C++ do this automatically by
// including the template source.  This in turn creates two copies of
// the static member variable.
//
// So to get around this problem, the *_SINGLETON_DECLARE macro is
// used to instruct the compiler to not create the second copy in the
// program.  This macro solution does not work for Borland C++, so for
// this compiler you must explicitly disable the template instantiation
// using a #pragma (or use the other workaround below).
//
// Another workaround for this is to not to expose the Singleton itself
// to the outside world, but to instead supply a function or static
// member function that returns the singleton to the executable
// (like get_dll_singleton () does below).

#if defined (__BORLANDC__)
# if !defined (TEST_BUILD_DLL)
#   pragma option push -Jgx
# endif
#endif
TEST_SINGLETON_DECLARE (ACE_Singleton, test_class, ACE_Null_Mutex)
#if defined (__BORLANDC__)
# if !defined (TEST_BUILD_DLL)
#   pragma option pop
# endif
#endif

typedef ACE_Singleton<test_class, ACE_Null_Mutex> TEST_SINGLETON;

Test_Export test_class *get_dll_singleton ();

2. dll.cpp 文件

// $Id: dll.cpp 80826 2008-03-04 14:51:23Z wotte $
#include "dll.h"

int test_variable = 0;

int
test_function ()
{
test_variable = RETVAL;
return RETVAL;
}

int
test_class::method ()
{
return RETVAL;
}

test_class *
get_dll_singleton ()
{
return TEST_SINGLETON::instance ();
}

#if defined (ACE_HAS_EXPLICIT_STATIC_TEMPLATE_MEMBER_INSTANTIATION)
template ACE_Singleton<test_class, ACE_Null_Mutex> *ACE_Singleton<test_class, ACE_Null_Mutex>::singleton_;
#endif /* ACE_HAS_EXPLICIT_STATIC_TEMPLATE_MEMBER_INSTANTIATION */

测试上面DLL的代码：

1. test_export.h 文件

// -*- C++ -*-
// $Id: test_export.h 80826 2008-03-04 14:51:23Z wotte $
// Definition for Win32 Export directives.
// This file is generated automatically by
// generate_export_file.pl
// ------------------------------
#if !defined (TEST_EXPORT_H)
#define TEST_EXPORT_H

#include "ace/config-all.h"

#if defined (ACE_AS_STATIC_LIBS) && !defined (TEST_HAS_DLL)
#  define TEST_HAS_DLL 0
#endif /* ACE_AS_STATIC_LIBS && ! TEST_HAS_DLL */

#if !defined (TEST_HAS_DLL)
#define TEST_HAS_DLL 1
#endif /* ! TEST_HAS_DLL */

#if defined (TEST_HAS_DLL)
#  if (TEST_HAS_DLL == 1)
#    if defined (TEST_BUILD_DLL)
#      define Test_Export ACE_Proper_Export_Flag
#      define TEST_SINGLETON_DECLARATION(T) ACE_EXPORT_SINGLETON_DECLARATION (T)
#      define TEST_SINGLETON_DECLARE(SINGLETON_TYPE, CLASS, LOCK) ACE_EXPORT_SINGLETON_DECLARE(SINGLETON_TYPE, CLASS, LOCK)
#    else
#      define Test_Export ACE_Proper_Import_Flag
#      define TEST_SINGLETON_DECLARATION(T) ACE_IMPORT_SINGLETON_DECLARATION (T)
#      define TEST_SINGLETON_DECLARE(SINGLETON_TYPE, CLASS, LOCK) ACE_IMPORT_SINGLETON_DECLARE(SINGLETON_TYPE, CLASS, LOCK)
#    endif /* TEST_BUILD_DLL */
#  else
#    define Test_Export
#    define TEST_SINGLETON_DECLARATION(T)
#    define TEST_SINGLETON_DECLARE(SINGLETON_TYPE, CLASS, LOCK)
#  endif   /* ! TEST_HAS_DLL == 1 */
#else
#  define Test_Export
#  define TEST_SINGLETON_DECLARATION(T)
#  define TEST_SINGLETON_DECLARE(SINGLETON_TYPE, CLASS, LOCK)
#endif     /* TEST_HAS_DLL */

#endif     /* TEST_EXPORT_H */

// End of auto generated file.

2. test.cpp 文件

// $Id: test.cpp 80826 2008-03-04 14:51:23Z wotte $

#include "dll.h"
#include <ace/streams.h>

int
ACE_TMAIN (int, ACE_TCHAR *[])
{
int failure_count = 0;
test_class my_test_class;

// Tet out the export of a class.  I don't see
// How this can fail at runtime (rather it would
// probably give link errors), but just in case...

cout << "Method Test: ";
if (my_test_class.method () != RETVAL)
{
cout << "Failed" << endl;
++failure_count;
}
else
cout << "Succeeded" << endl;

// Test out the export of a function.  Like above,
// I don't know how this can fail at runtime.

cout << "Function Test: ";
if (test_function () != RETVAL)
{
cout << "Failed" << endl;
++failure_count;
}
else
cout << "Succeeded" << endl;

// Also test out the export of data.

cout << "Variable Test: ";
if (test_variable != RETVAL)
{
cout << "Failed" << endl;
++failure_count;
}
else
cout << "Succeeded" << endl;

// Test out the ACE_Singleton export by checking to see
// that we have the same instance pointer as the DLL does.
// This can fail at runtime.

cout << "Singleton Test: ";
if (TEST_SINGLETON::instance () != get_dll_singleton ())
{
cout << "Failed" << endl;
++failure_count;
}
else
cout << "Succeeded" << endl;

getchar();

// Return the number of failures
return failure_count;
}