使用UnmanagedExports和JNA将字节数组从C#返回到Java

我最近发现库 UnmanagedExports 允许我使用 JNA直接从Java访问C#-methods.

有没有人知道我尝试将字节数组从C#返回给Java有什么问题？

这是我的例子：

C#代码：

using System;
using RGiesecke.DllExport;
namespace JnaTestLibrary
{
  public class JnaTest
  {
    [DllExport]
    public static byte[] returnT1()
    {
        byte[] t1 = {1,2,3,4,5};
        return t1;
    }
  }
}

Java代码：

package me.mt.test;
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Platform;
public class JnaTest {
  public interface JnaTestInterface extends Library{
      byte[] returnT1();
  }
  static JnaTestInterface jnaTest = null;

  static{       
        if(Platform.is64Bit()){
            jnaTest = (JnaTestInterface)Native.loadLibrary("JnaTestLibrary64",JnaTestInterface.class);
        }
        else{
            jnaTest = (JnaTestInterface)Native.loadLibrary("JnaTestLibrary86",JnaTestInterface.class);
        }
    }

  public byte[] returnT1(){
      return jnaTest.returnT1();
  }
}

Java异常：

Exception in thread "main" java.lang.IllegalArgumentException: Unsupported return type class [I in function returnT1

解决方法

我通过使用指针解决了这个问题.

C#代码：

using System;
using RGiesecke.DllExport;
namespace JnaTestLibrary
{
  public class JnaTest
  {
    [DllExport]
    public unsafe static byte* returnT1()
    {
        byte[] t1 = {1,5};
        fixed (byte* p1 = t1)
        {
          return p1;
        }
    }
  }
}

Java代码：

package me.mt.test;
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Platform;
import com.sun.jna.Pointer;
public class JnaTest {
  public interface JnaTestInterface extends Library{
      Pointer returnT1();
  }
  static JnaTestInterface jnaTest = null;

  static{       
        if(Platform.is64Bit()){
            jnaTest = (JnaTestInterface)Native.loadLibrary("JnaTestLibrary64",JnaTestInterface.class);
        }
    }

  public byte[] returnT1(){
      Pointer p1 = jnaTest.returnT1();
      return p1.getByteArray(0,5);
  }
}