JNI -“无法打开包含文件:'jni_md.h'”

This sample program is meant to call a native method written in C.

这个示例程序的目的是调用用C编写的本机方法。

Java Code

Java代码

class HelloWorld {

    private native void print();

    public static void main( String args[] ) {
        new HelloWorld().print();
    }

    static {
        System.loadLibrary("HelloWorld");
    }

}

After writing this i compiled the program and generated a JNI style header file.

编写完这个程序后，我编译了这个程序并生成了一个JNI样式的头文件。

The header file generated is :

生成的头文件为:

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <C:\Program Files\Java\jdk1.7.0\include\jni.h>
/* Header for class HelloWorld */

#ifndef _Included_HelloWorld
#define _Included_HelloWorld
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     HelloWorld
 * Method:    print
 * Signature: ()V
 */
 JNIEXPORT void JNICALL Java_HelloWorld_print
 (JNIEnv *, jobject);

 #ifdef __cplusplus
 }
 #endif
 #endif

And the native method written in c

用c写的原生方法

#include <C:\Program Files\Java\jdk1.7.0\include\jni.h>
#include <C:\Program Files\Java\jdk1.7.0\include\win32\jni_md.h>
#include <stdio.h>
#include "HelloWorld.h"

JNIEXPORT void JNICALL Java_HelloWorld_print( JNIENv *env , jobject obj) {
    printf("Hello World!\n");
    return;
}

The error I get on compiling is fatal error C1083: Cannot open include file: 'jni_md.h': No such file or directory

我在编译时得到的错误是致命错误C1083:无法打开include文件:'jni_md。没有这样的文件或目录。

Also my compiler underlines jobject obj saying that this class does not have storage class or specifier . It underlines *env saying expected a ')'.

我的编译器也强调jobject obj说这个类没有存储类或说明符。它强调*env表示“预期a”)。

Why do I get this error ?

为什么会出现这个错误?

4 个解决方案

#1

I suspect that jni.h is trying to #include <jni_md.h>, which is then failing because you haven't added its location to your include path.

我怀疑jni。h试图#include ，它会失败因为你没有将它的位置添加到你的include路径中。。h>

Try adding both of these entries to your C compiler's include path:

尝试将这两个条目添加到C编译器的include路径:

C:\Program Files\Java\jdk1.7.0\include
C:\Program Files\Java\jdk1.7.0\include
C:\Program Files\Java\jdk1.7.0\include\win32
C:\Program Files\Java\jdk1.7.0\include\win32

The win32 path might not be necessary, depending on how jni.h is set up.

根据jni的方式，可能不需要win32路径。h是设置。

#2

Try this,

试试这个,

HelloWorld.c

#include "HelloWorld.h"
#include <stdio.h>

JNIEXPORT void JNICALL Java_HelloWorld_print(JNIEnv *env, jobject obj)
{
  printf("Hello World!\n");
  return;
}

Compile it using cl.exe (I'm using VC++ and CL.EXE required following command line switches.)

使用cl编译它。exe(我用的是vc++和CL。EXE需要以下命令行切换)

c:\>cl -c /I"c:\Program Files\java\jdk1.7.0\include" /I"c:\Prog ram Files\java\jdk1.7.0\include\win32" HelloWorld.c

\>cl -c /I"c:\程序文件\java\jdk1.7.0\包含" /I"c:\Program文件\java\jdk1.7.0\include win32" helloworldc

Link .obj module

链接.obj模块

c:\>link /libpath="c:\Program Files\java\jdk1.7.0\lib" HelloWorld.obj /dll

c:\ >链接/ libpath = " c:\ Program Files \ java \ jdk1.7.0 \ lib”HelloWorld。obj / dll

#3

I had this issue once, my solution was actually to edit the jni.h's internal #include from "jni_md.h" to "win32/jni_md.h", although there is probably a less hacky way you are supposed to do it.

我曾经遇到过这个问题，我的解决方案实际上是编辑jni。h的内部#include来自“jni_md”。h”到“win32 / jni_md。h，尽管你应该用一种不太常见的方式来做这件事。

#4

-2

Just copy jni_md.h file to folder where jni.h.

只是jni_md副本。h文件到jni.h的文件夹。

#1