Eclipse中使用JNI调用C++ build的dll

最新推荐文章于 2025-08-13 19:57:41 发布

原创最新推荐文章于 2025-08-13 19:57:41 发布 · 3k 阅读

1 ·

CC 4.0 BY-SA版权

文章标签：

#eclipse #c++ #jni #build #java #dll

本文介绍如何在 Eclipse 中通过 JNI 让 Java 应用调用 C++ 编译的 DLL 文件。文章详细说明了创建 Java 类、生成 H 文件、实现 C++ 函数、编译 DLL 和配置 Eclipse 的全过程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Eclipse中使用JNI调用C++ build的dll

- Uper

最近想写个从java程序中调用C++生成的dll的工具. 在网上搜索一些帖子，大概过程如下：

1. 建立自己的JAVA 类，该类带有一个or多个native声明的方法

2. 使用javac，生成.CLASS 文件

3. 使用javah，生成*.H文件

4. 根据*.H文件完成C++的dll

5. copy该dll到class所在的folder下

6. 使用java运行该application 即可.

但是当我把相关内容移到eclipse上时，总是throw exception:java.lang.UnsatisfiedLinkError异常，后发现是我的*.h文件生成有问题。

下面把我的过程描述一下，以便参考:

Eclipse side

1. Create java class named SWIFTAlianceCASmfTest with function of declared native

      package test.cs.web;
      import java.lang.*;
       public class SWIFTAlianceCASmfTest{
            public native static int calculate(int addone);
            public static void main(String arg[]){
            try{
            SWIFTAlianceCASmfTest objTest = new SWIFTAlianceCASmfTest();
            int add1 = 3;
            int add2 = SWIFTAlianceCASmfTest.calculate(add1);
            System.out.println("The result is "+add2);
            }catch(Exception ex){
                  System.out.println("The result is "+add2);
            }
            }
            static {
                System.loadLibrary("mycalculate");
            }
      }

2. Save it and eclipse will build and generate class file SWIFTAlianceCASmfTest.class in folder ../WEB-INF/CLASSES/test/cs/web/

3. Go to the folder ../WEB-INF/CLASSES/

Execute command javah -jni test.cs.web.SWIFTAlianceCASmfTest

Note: test.cs.web is package name and not lose it.

The file test_cs_web_SWIFTAlianceCASmfTest.h will be generated. Refer to below:

/* DO NOT EDIT THIS FILE - it is machine generated */

#include <jni.h>

/* Header for class test_cs_web_SWIFTAlianceCASmfTest */

#ifndef _Included_test_cs_web_SWIFTAlianceCASmfTest

#define _Included_test_cs_web_SWIFTAlianceCASmfTest

#ifdef __cplusplus

extern "C" {

#endif

* Class: test_cs_web_SWIFTAlianceCASmfTest

* Method: calculate

* Signature: (I)I

JNIEXPORT jint JNICALL Java_test_cs_web_SWIFTAlianceCASmfTest_calculate

(JNIEnv *, jclass, jint);

#ifdef __cplusplus

}

#endif

4. C++ side: According to head file test_cs_web_SWIFTAlianceCASmfTest.h, build dll named mycalculate.dll using VC and implement function Java_test_cs_web_SWIFTAlianceCASmfTest_calculate(,,)

.cpp

#include "jni.h";
#include "test_cs_web_SWIFTAlianceCASmfTest.h";

JNIEXPORT jint JNICALL Java_test_cs_web_SWIFTAlianceCASmfTest_calculate
(JNIEnv *env, jclass obj, jint nAdd1)
{
return (nAdd1+nAdd1);
}

.def

LIBRARY LIB
EXPORTS
Java_test_cs_web_SWIFTAlianceCASmfTest_calculate @ 1

In VC tools, include the path of files jni.h & jni_md.h in JDK install directory.

5. Eclipse side: copy mycalculate.dll to folder ../WEB-INF/CLASSES/

Set Eclipse VM arguments: -Djava.library.path=<the position of mycalculate.dll located in> fgdsf

6. Run Java application in Eclipse and it will return result:The result is 6

以上有2点需要注意：

1. don't forget the package name when you generate head file by tool javah

2. the path of dll file and path of running command javah make is correctly.