如何在JNA中使用Java的这种方法？

Question

我想通过JNA在C++ dll和我的java项目之间建立一个连接。 dll.h在这个gitHub中：dll.h。

EXTERN_C DLLEXPORT int STDCALL SolveBoard(
    struct deal dl, 
    int target, 
    int solutions, 
    int mode, 
    struct futureTricks * futp, 
    int threadIndex); 
struct deal 
{ 
    int trump; 
    int first; 
    int currentTrickSuit[3]; 
    int currentTrickRank[3]; 
    unsigned int remainCards[DDS_HANDS][DDS_SUITS]; 
}; 
struct futureTricks 
{ 
    int nodes; 
    int cards; 
    int suit[13]; 
    int rank[13]; 
    int equals[13]; 
    int score[13]; 
}; 

我新鲜JNA和C++，我试图代码的Java这样的：

public interface DllAl extends StdCallLibrary{ 
DllAl instanceDll = (DllAl)Native.loadLibrary("dds",DllAl.class); 
public int SolveBoard(deal deal,int target,int solutions,int mode, futureTricks fut,int threadIndex); 
public int PrintFut(char title[],futureTricks fut); 

public static class deal extends Structure{ 
     public int trump; 
     public int first; 
     public int currentTrickSuit[] = new int [3]; 
     public int currentTrickRank[] = new int [3]; 
     public int remainCards[][] = new int[4][4]; 
     public static class ByReference extends deal implements Structure.ByReference {} 
     public static class ByValue extends deal implements Structure.ByValue {} 
     @Override 
     protected List<String> getFieldOrder() { 
      return Arrays.asList(new String[]{"trump", "first", "currentTrickSuit", "currentTrickRank","remainCards"}); 
     } 

} 
public static class futureTricks extends Structure{ 
    public int nodes; 
    public int cards; 
    public int suit[] = new int [13]; 
    public int rank[] = new int [13]; 
    public int equals[] = new int[13]; 
    public int score[] = new int[13]; 
     public static class ByReference extends futureTricks implements Structure.ByReference {} 
     public static class ByValue extends futureTricks implements Structure.ByValue {} 
     @Override 
     protected List<String> getFieldOrder() { 
      return Arrays.asList(new String[]{"nodes", "cards", "suit", "rank","equals","score"}); 
     } 

} 

} 但是，它会返回错误：

Exception in thread "main" java.lang.NullPointerException 
at java.lang.reflect.Array.getLength(Native Method) 
at com.sun.jna.Native.getNativeSize(Native.java:1162) 
at com.sun.jna.Structure.getNativeAlignment(Structure.java:1360) 
at com.sun.jna.Structure.getNativeAlignment(Structure.java:1385) 
at com.sun.jna.Structure.deriveLayout(Structure.java:1221) 
at com.sun.jna.Structure.calculateSize(Structure.java:1053) 
at com.sun.jna.Structure.allocateMemory(Structure.java:380) 
at com.sun.jna.Structure.ensureAllocated(Structure.java:356) 
at com.sun.jna.Structure.ensureAllocated(Structure.java:346) 
at com.sun.jna.Structure.write(Structure.java:737) 
at com.sun.jna.Structure.autoWrite(Structure.java:2047) 
at com.sun.jna.Function.convertArgument(Function.java:512) 
at com.sun.jna.Function.invoke(Function.java:305) 
at com.sun.jna.Library$Handler.invoke(Library.java:236) 
at com.sun.proxy.$Proxy0.SolveBoard(Unknown Source) 
at DllAl.main(DllAl.java:98) 

Answer 1

JNA做不映射2D（或3D，4D等）阵列。如果您需要映射二维数组you should replace it with a 1D array，然后编写自己的代码进行翻译。

你需要改变这一行：

public int remainCards[][] = new int[4][4]; 

到：

public int remainCards[] = new int[16]; 

然后转换二维坐标（例如，手，套装）的方法添加到1D指数（例如， 4 *手+套装）。