使用UnmanagedExports和JNA将字节数组从C#返回到Java

我最近发现了一个库，它允许我使用Java直接访问C方法

有人知道我试图将字节数组从C#返回到Java的错误是什么吗

以下是我的例子：

C#代码：

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();
  }
}

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);
        }
        else{
            jnaTest = (JnaTestInterface)Native.loadLibrary("JnaTestLibrary86", JnaTestInterface.class);
        }
    }

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

Java异常：

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

---

我用指针解决了这个问题

C#代码：

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();
  }
}

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);
        }
        else{
            jnaTest = (JnaTestInterface)Native.loadLibrary("JnaTestLibrary86", JnaTestInterface.class);
        }
    }

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

---

我对jna了解不多，但我相信ByteBuffers（特别是直接变量）可以用于跨本机边界传递字节数组。我认为指向的数据可能会被

jnaTest.returnT1（）

和

p1.getByteArray（0，5）之间的CLR垃圾收集所破坏

@TomBlodget

unsafe

关键字根本不会改变普通代码的语义。到目前为止，一切都很顺利。你靠的是运气。看这个。基本问题是内存所有权，以及所有权的转移（取决于技术）。将所有权返还给CLR后，您正在使用

fixed

语句范围之外的内存。