使用Java中的C接口调用DLL [英] Calling DLL with a C interface from Java

问题描述

我试图在第三方DLL中调用本机方法，该方法具有C接口，方法如下：

  DWORD ExampleInterfaceMethod（DWORD Mode，LPSTR Header）; 
  

我已经使用以下方式成功加载了DLL：

 的System.loadLibrary（ DLLNAME）; 
  

我创建了一个方法：

  protected native int ExampleInterfaceMethod（int type，int Nth，byte [] name）; 
  

此方法似乎没有使用正确的变量类型，因为每当我将其称为以下抛出错误：

 java.lang.UnsatisfiedLinkError：com.DLLTest.ExampleInterfaceMethod（II [B] I 

什么变量类型需要在Java中使用才能调用这个方法，或者我还缺少其他东西？

解决方案

使用JNI您需要特殊命名的C函数来实现Java native 方法。您不能简单地添加一个 native 方法来调用现有的C函数 - 而是正常的方法是创建一个调用现有C函数的包装器C函数，并被命名正确的方式。

您可能需要查看 JNA 。这是JNI上的一个包装器，它允许您从Java端调用C函数，而无需手动编写适应的本机代码。

I'm attempting to call native methods within a 3rd party DLL, which has a C interface with methods such as:

DWORD ExampleInterfaceMethod( DWORD Mode, LPSTR Header );

I've successfully loaded the DLL using:

System.loadLibrary("DLLName");

and I've created a method:

protected native int ExampleInterfaceMethod(int type, int Nth, byte[] name);

This method doesn't seem to be using the correct variable types, as whenever I call it the following error is thrown:

java.lang.UnsatisfiedLinkError: com.DLLTest.ExampleInterfaceMethod(II[B)I

What variable types do I need to use in Java in order to call this method, or am I missing something else?

解决方案

With JNI, you need specially-named C functions to implement your Java native methods. You can't simply add a native method to call an existing C function - instead the normal way is creating a "wrapper" C function which calls the existing one, and is named the right way.

You might want to have a look at JNA. This is a wrapper around JNI which allows you to call C functions from the Java side without manually writing adapting native code for this.

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