我有一个在Linux上运行的Java应用程序，通过JNA与编写为C语言的共享对象的库进行对话。我希望能够在Windows上运行它，所以我在Cygwin下编译了库而没有问题
问题是当我尝试用.dll文件替换.so文件时，它在我调用函数时不起作用。
为了简化问题，我制作了一个非常简单的DLL和Java程序，如下所示：
test.h
__declspec(dllexport) void Test();
test.c的
#include <stdio.h>
#include "test.h"
void Test()
{
printf("Hello from Test!\n");
}
TestJNA.java
package testjna;
import com.sun.jna.Library;
import com.sun.jna.Native;
public class TestJNA {
public interface CLibrary extends Library {
CLibrary INSTANCE = (CLibrary)Native.loadLibrary(System.getProperty("jna.library.path"), CLibrary.class);
void Test();
}
public static void main(String[] args) {
System.setProperty("jna.library.path", "absolute\\path\\to\\test.dll");
System.out.println("Starting test...");
CLibrary.INSTANCE.Test();
System.out.println("Test done!");
}
}
如果我在VS2015中编译DLL并将其复制，一切都按预期工作：
dist>java -jar TestJNA.jar
Starting test...
Hello from Test!
Test done!
然后我尝试在Cygwin中编译DLL，如下所示：
gcc -c test.c
gcc -shared -o test.dll test.o
这会生成一个DLL，如果我在Depedency Walker中加载它，我可以确认有一个导出的函数Test。但是，当我将test.dll和Cygwin1.dll一起放入正确的目录并运行Java应用程序时，它将输出“Starting test ...”，然后在几秒钟后退出而没有任何错误。
我尝试删除__declspec(dllexport)并按照here所述重新编译，但我仍然得到相同的结果。
我正在运行64位JVM：
C:\>java -version
java version "1.8.0_111"
Java(TM) SE Runtime Environment (build 1.8.0_111-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.111-b14, mixed mode)
64位版本的Cygwin：
$ uname -a
CYGWIN_NT-6.1 computername 2.6.0(0.304/5/3) 2016-08-31 14:32 x86_64 Cygwin
我已经确认GCC生成的DLL是64位。
有谁知道我做错了什么？
以下是所请求的每个DLL的nm输出：
Cygwin编译的DLL
$ nm test.dll
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000000042abc506c p .pdata
000000042abc5060 p .pdata
000000042abc5000 p .pdata
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0000000000000000 A .weak.__real__ZdaPv._cygwin_crt0_common
0000000000000000 A .weak.__real__ZdaPvRKSt9nothrow_t._cygwin_crt0_common
0000000000000000 A .weak.__real__ZdlPv._cygwin_crt0_common
0000000000000000 A .weak.__real__ZdlPvRKSt9nothrow_t._cygwin_crt0_common
0000000000000000 A .weak.__real__Znam._cygwin_crt0_common
0000000000000000 A .weak.__real__ZnamRKSt9nothrow_t._cygwin_crt0_common
0000000000000000 A .weak.__real__Znwm._cygwin_crt0_common
0000000000000000 A .weak.__real__ZnwmRKSt9nothrow_t._cygwin_crt0_common
000000042abc1000 T .weak._Jv_RegisterClasses.__dso_handle
000000042abc6044 r .xdata
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000000042abc603c r .xdata
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000000042abc6028 r .xdata
000000042abc601c r .xdata
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U ___crt_xc_end__
U ___crt_xc_start__
U ___crt_xi_end__
U ___crt_xi_start__
U ___crt_xl_start__
U ___crt_xp_end__
U ___crt_xp_start__
U ___crt_xt_end__
U ___crt_xt_start__
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U ___tls_end__
U ___tls_start__
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U __end__
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0000000000000000 A __loader_flags__
0000000000000000 A __major_image_version__
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0000000000000000 A __minor_image_version__
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0000000000000003 A __subsystem__
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w _Jv_RegisterClasses
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w _ZdaPv
w _ZdaPvRKSt9nothrow_t
w _ZdlPv
w _ZdlPvRKSt9nothrow_t
w _Znam
w _ZnamRKSt9nothrow_t
w _Znwm
w _ZnwmRKSt9nothrow_t
000000042abc1640 T calloc
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000000042abc1620 T cygwin_premain3
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000000042abc9114 i fthunk
000000042abc16a8 T GetModuleHandleA
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000000042abc909c i hname
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000000042abc10c0 T puts
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000000042abc16b0 t register_frame_ctor
000000042abc7020 b storedHandle
000000042abc7010 b storedPtr
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000000042abc7040 b u.52838
Visual Studio编译DLL
$ nm test.dll.vs
nm: test.dll.vs: no symbols
所以我尝试使用额外的参数-Wl,--out-implib=test.lib在Cygwin中编译来创建.lib文件。然后我在Visual Studio中创建了一个简单的测试程序，并链接到库文件并运行调试器。当试图调用该函数时，我得到以下异常：
Exception thrown at 0x0000000180117A37 (cygwin1.dll) in RunTestDLL.exe: 0xC0000005: Access violation writing location 0xFFFFFFFF00020000.
地址似乎随着尝试运行而改变。
这反过来导致我在StackOverflow here上的另一个线程，其中有人有类似的问题。基于该线程，听起来问题在于动态加载cygwin1.dll而不是我的DLL。而且由于我似乎无法找到任何关于在堆栈中保留空间的信息，我得出的结论是，我现在想做的事情是不可能的。