从Java中使用JNA调用DLL [英] Call DLL from Java using JNA

问题描述

我是新来使用JNA从Java访问的DLL。我需要一个DLL（.NET编写）内的类访问方法。构成本示例DLL下面，我试图让AuditID和服务器ID。我结束与下面的错误，而我正在我的code。任何指导真的AP preciated。

///错误///

 在线程异常主要java.lang.UnsatisfiedLinkError中：错误查找功能GetEnrollcontext：指定的程序无法找到。
 

// DLL文件code //

  SampleDLL.ProfileEnroll enrollcontext =新SampleDLL.ProfileEnroll（）;
enrollcontext.Url =URL;
enrollcontext.AuditIdType = SampleDLL.ProfileId;
enrollcontext.AuditId =22222222;
enrollcontext.ServerId =服务器1;
 

///的Java code ///

 进口com.sun.jna.Library;
进口com.sun.jna.Native;
进口com.sun.jna.Structure;
进口dllExtract.DLLExtractTest.SampleDLL.Enrollcontext;


公共类SampleDLLExtract {

    公共接口SampleDLL扩展库{
        SampleDLL INSTANCE =（SampleDLL）Native.loadLibrary（SampleDLL
            SampleDLL.class）;

        公共静态类Enrollcontext扩展结构{

            公共字符串auditId;
            公共字符串服务器ID;
        }
            无效GetEnrollcontext（Enrollcontext EC）; //无效（）;
    }
    公共静态无效的主要（字串[] args）{
        SampleDLL SDLL = SampleDLL.INSTANCE;
        SampleDLL.Enrollcontext enrollContext =新SampleDLL.Enrollcontext（）;
        sdll.GetEnrollcontext（enrollContext）;

        的System.out.println（sdll.toString（sdll.GetEnrollcontext（enrollContext）））;
    }
}
 

解决方案

其实有一个解决方案，为您在Java中（而不是其他）使用C＃，VB.NET和F＃code通过JNA！而且它也很容易使用： https://www.nuget.org/packages/UnmanagedExports

本包装所有你需要做的是，添加[RGiesecke.DllExport.DllExport]你的方法那样：

C＃的.dll项目：

  [RGiesecke.DllExport.DllExport]
公共静态字符串yourFunction（字符串yourParameter）
{
    返回CSHARP字符串;
}
 

Java项目：

 公共接口JNA扩展库{
    JNA INSTANCE =（JNA）Native.loadLibrary（yourCSharpProject.dll，jna.class）;
公共字符串yourFunction（字符串yourParameter）;
}
 

使用在code：

 的System.out.println（jna.INSTANCE.yourFunction（nothingImportant））;
 

中提琴！

前面已经提到过它的工作原理非常简单，但这种方法有一定的局限性：

• 仅可用于简单数据类型作为参数及放大器;返回值
• 在没有可用的MethodOverloading。 yourFunction（字符串yourParameter）和yourFunction（字符串yourParameter，字符串yourSecondParameter）不起作用！你有他们不同的名字
• 使用数组作为参数或返回值。 （JNA提供字符串数组，但我不能够使用它们在C＃中）（也许有一个解决方案，但我不能拿出一个为止！）
• 如果您导出方法，你可以不在内部在C＃code调用它（简单的绕过了以下内容：

  [RGiesecke.DllExport.DllExport]
公共静态布尔externalAvailable（字符串yourParameter）
{
    返回yourInternalFunction（yourParameter）;
}
 

使用C＃它的伟大工程，用VB.NET和F＃我没有经验。 希望这有助于！

I am new to accessing DLLs from Java using JNA. I need to access methods from a class within a DLL(written in .net). Form this sample DLL below, I am trying to get AuditID and Server ID. I am ending with the following error while I am running my code. Any guidance really appreciated.

/// Error ///

 Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function  'GetEnrollcontext': The specified procedure could not be found.

//DLL File Code//

SampleDLL.ProfileEnroll enrollcontext = new SampleDLL.ProfileEnroll();
enrollcontext.Url =" url";
enrollcontext.AuditIdType = SampleDLL.ProfileId;
enrollcontext.AuditId = "22222222 "; 
enrollcontext.ServerId = "server1";

/// Java Code ///

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Structure;
import dllExtract.DLLExtractTest.SampleDLL.Enrollcontext;


public class SampleDLLExtract {

    public interface SampleDLL extends Library {
        SampleDLL INSTANCE = (SampleDLL) Native.loadLibrary("SampleDLL",
            SampleDLL.class);

        public static class Enrollcontext extends Structure { 

            public String auditId;
            public String serverId;
        }
            void GetEnrollcontext(Enrollcontext ec);                     // void ();
    }
    public static void main(String[] args) {
        SampleDLL sdll = SampleDLL.INSTANCE;
        SampleDLL.Enrollcontext enrollContext = new SampleDLL.Enrollcontext();
        sdll.GetEnrollcontext(enrollContext);

        System.out.println(sdll.toString(sdll.GetEnrollcontext(enrollContext))); 
    }
}

解决方案

in fact there is a solution for you to use C#, VB.NET or F# code via JNA in Java (and nothing else)! and it is also very easy to use: https://www.nuget.org/packages/UnmanagedExports

with this package all you need to do is, add [RGiesecke.DllExport.DllExport] to your methods like that:

C# .dll Project:

[RGiesecke.DllExport.DllExport]
public static String yourFunction(String yourParameter)
{
    return "CSharp String";
}

Java Project:

public interface jna extends Library {
    jna INSTANCE = (jna) Native.loadLibrary("yourCSharpProject.dll", jna.class);
public String yourFunction(String yourParameter);
}

use it in the code:

System.out.println(jna.INSTANCE.yourFunction("nothingImportant"));

Viola!

As already mentioned it works very easy, but this solution has some limitations:

• only available for simple datatypes as parameter & return values
• no MethodOverloading available. yourFunction(String yourParameter) and yourFunction(String yourParameter, String yourSecondParameter) does not work! you have to name them differently
• Use arrays as parameter or return values. (JNA offers StringArray, but I am not able to use them in C#) (maybe there is a solution, but I couldn't come up with one so far!)
• if you export a method you can't call it internally in your C# code (simple to bypass that by the following:

.

[RGiesecke.DllExport.DllExport]
public static Boolean externalAvailable(String yourParameter)
{
    return yourInternalFunction(yourParameter);
}

With C# it works great, with VB.NET and F# I have no experience. hope this helps!

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