Echec lors du didacticiel JNI de Java

Bonjour,

En cherchant sur le net un guide pour apprendre JNI, je suis tombé sur une page officielle de JAVA. Je ne pouvais pas rêver mieux, donc...
http://java.sun.com/developer/online.../jniexamp.html

Le tuto décrit un programme qui lit le contenu d'un fichier et l'affiche dans la console.
La lecture du fichier est fait en C, et l'affichage, et JAVA.

Le guide me dit de créer 3 fichiers: ReadFile.java, Readfile.h (généré par javah), et Readfile.cpp

Readfile.java

Code:

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import java.util.*;   public class ReadFile {   //Native method declaration native byte[] loadFile( String name );   //Load the library static { System.loadLibrary( "nativelib" ); }   public static void main( String args[] ) {   byte buf[];   // Create class instance ReadFile mappedFile = new ReadFile();   // Call native method to load ReadFile.java buf = mappedFile.loadFile( "ReadFile.java" );   //Print contents of ReadFile.java for( int i=0;i < buf.length;i++ ) { System.out.print( (char)buf[ i ] ); } } }

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ReadFile.h

Code:

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/* DO NOT EDIT THIS FILE - it is machine generated */ #include <jni.h> /* Header for class ReadFile */   #ifndef _Included_ReadFile #define _Included_ReadFile   #ifdef __cplusplus extern "C" { #endif   /*  * Class: ReadFile  * Method: loadFile  * Signature: (Ljava/lang/String;)[B  */ JNIEXPORT jbyteArray JNICALL Java_ReadFile_loadFile( JNIEnv*, jobject, jstring );   #ifdef __cplusplus } #endif   #endif

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ReadFile.cpp

Code:

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#include <jni.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/shm.h> #include <sys/mman.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h>   JNIEXPORT jbyteArray JNICALL Java_ReadFile_loadFile( JNIEnv* env, jobject jobj, jstring name ) {   caddr_t m; jbyteArray jb; jboolean iscopy;   struct stat finfo;   const char *mfile = (*env)->GetStringUTFChars( env, name, &iscopy );   int fd = open( mfile, O_RDONLY );   if( fd == -1 ) { printf( "Could not open %s\n", mfile ); }   lstat( mfile, &finfo );   m = mmap( (caddr_t) 0, finfo.st_size, PROT_READ, MAP_PRIVATE, fd, 0 );   if( m == (caddr_t) - 1 ) { printf( "Could not mmap %s\n", mfile );   return( 0 ); }   jb = (*env)->NewByteArray( env, finfo.st_size);   (*env)->SetByteArrayRegion( env, jb, 0, finfo.st_size, (jbyte *)m );   close( fd );   (*env)->ReleaseStringUTFChars( env, name, mfile );   return ( jb ); }

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J'ai installé MinGW sur Windows, et je dispose de GCC.

Donc, à la commande:

Code:

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cl -Ic:/jdk1.2/include -Ic:/jdk1.2/include/win32 -LD nativelib.c -Felibnative.dll

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... j'ai plutôt fait:

Code:

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1 2	gcc -Wall -shared ReadFile.cpp -o nativelib.dll -I"c:\Program Files\Java\jdk1.6.0_11\include" -I"c:\Program Fil es\Java\jdk1.6.0_11\include" -L"c:\Program Files\Java\jdk1.6.0_11\lib"

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là-dessus, la console m'affiche des centaines de pages d'erreurs. Voici la fin, pour vous donnez une idée.

Code:

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... ... c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1822: error: 'const struct JNINativeInterface_' has no member named 'DeleteWeakGlobalRef' c:/Program Files/Java/jdk1.6.0_11/include/jni.h: In member function `jboolean JNIEnv_::ExceptionCheck()': c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1826: error: 'const struct JNINativeInterface_' has no member named 'ExceptionCheck' c:/Program Files/Java/jdk1.6.0_11/include/jni.h: In member function `_jobject* JNIEnv_::NewDirectByteBuffer(void*, int)': c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1830: error: 'const struct JNINativeInterface_' has no member named 'NewDirectByteBuffer' c:/Program Files/Java/jdk1.6.0_11/include/jni.h: In member function `void* JNIEnv_::GetDirectBufferAddress(_jobject*)': c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1833: error: 'const struct JNINativeInterface_' has no member named 'GetDirectBufferAddress' c:/Program Files/Java/jdk1.6.0_11/include/jni.h: In member function `jobjectRefType JNIEnv_::GetObjectRefType(_jobject*)': c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1839: error: 'const struct JNINativeInterface_' has no member named 'GetObjectRefType' c:/Program Files/Java/jdk1.6.0_11/include/jni.h: At global scope: c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1851: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1853: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1859: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1877: error: `JNICALL' has not been declared c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1877: error: ISO C++ forbids declaration of `jint' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1877: error: `jint' declared as function returning a function c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1877: error: ISO C++ forbids declaration of `DestroyJavaVM' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1879: error: `JNICALL' has not been declared c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1879: error: ISO C++ forbids declaration of `jint' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1879: error: `jint' declared as function returning a function c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1879: error: ISO C++ forbids declaration of `AttachCurrentThread' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1879: error: `int JNIInvokeInterface_::jint(int*)' and `int JNIInvokeInterface_::jint(int*)' cannot be overloaded c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1881: error: `JNICALL' has not been declared c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1881: error: ISO C++ forbids declaration of `jint' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1881: error: `jint' declared as function returning a function c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1881: error: ISO C++ forbids declaration of `DetachCurrentThread' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1881: error: `int JNIInvokeInterface_::jint(int*)' and `int JNIInvokeInterface_::jint(int*)' cannot be overloaded c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: `JNICALL' has not been declared c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: `jint' is not a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: ISO C++ forbids declaration of `jint' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: ISO C++ forbids declaration of `version' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: `jint' declared as function returning a function c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: ISO C++ forbids declaration of `GetEnv' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1883: error: `int JNIInvokeInterface_::jint(int*)' and `int JNIInvokeInterface_::jint(int*)' cannot be overloaded c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1885: error: `JNICALL' has not been declared c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1885: error: ISO C++ forbids declaration of `jint' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1885: error: `jint' declared as function returning a function c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1885: error: ISO C++ forbids declaration of `AttachCurrentThreadAsDaemon' with no type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1885: error: `int JNIInvokeInterface_::jint(int*)' and `int JNIInvokeInterface_::jint(int*)' cannot be overloaded c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1892: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1895: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1898: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1902: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1905: error: `jint' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1916: error: `JNIIMPORT' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1919: error: `JNIIMPORT' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1922: error: `JNIIMPORT' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1926: error: `JNIEXPORT' does not name a type c:/Program Files/Java/jdk1.6.0_11/include/jni.h:1929: error: expected constructor, destructor, or type conversion before "void" ReadFile.cpp:3:21: sys/ipc.h: No such file or directory ReadFile.cpp:4:21: sys/shm.h: No such file or directory ReadFile.cpp:5:22: sys/mman.h: No such file or directory ReadFile.cpp:10: error: `JNIEXPORT' does not name a type

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Je ne sais pas où se situe mon erreur... est-ce dans la ligne de commande de compilation, dans la configuration des mes PATHS..?

Ce doit être une erreur facile à régler pour qui a déjà travaillé avec JNI.

Dans le cas où un expert JNI passerait dans les parages, j'aimerais lui demander ce qui, selon lui, vaut la peine d'être externalisé dans un code C/C++, et ce qui n'en vaut pas la peine.

Merciiiii

J'ai simplifié le problème en éditant un programme bien plus simple, qui toutefois ne fonctionne toujours pas.
J'ai rassemblé les fichiers dans un fchier ZIP:Pièce jointe 41222, pour que vous puissiez tester vous-même.

L'archive contient 3 fichiers:

testJNI.java

Code:

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public class TestJNI {   static { System.loadLibrary( "jnidll" ); }   public static native String onePlusOne();   public static void main( String args[] ) {   System.out.println( onePlusOne() ); }   }

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testJNI.c

Code:

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#include <jni.h>   /*  * Class: TestJNI  * Method: onePlusOne  * Signature: ()Ljava/lang/String;  */ JNIEXPORT jstring JNICALL Java_TestJNI_onePlusOne( JNIEnv* env, jclass jClass ) {   return (*env)->NewStringUTF( env, "2" ); }

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compile.cmd

Code:

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javac TestJNI.java javah -jni TestJNI gcc -I"c:\Program Files\Java\jdk1.6.0_07\include" -I"c:\Program Files\Java\jdk1.6.0_07\include\win32" -c TestJNI.c gcc -shared -o jnidll.dll TestJNI.o

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Vous l'aurez compris, je lance compile.cmd pour simplifier la compilation.

L'effet est le même. Quand je lance "java TestJNI", l'erreur suivante s'affiche:

Code:

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Exception in thread "main" java.lang.UnsatisfiedLinkError: TestJNI.onePlusOne()Ljava/lang/String; at TestJNI.onePlusOne(Native Method) at TestJNI.main(TestJNI.java:12)

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Salut,


J'avais fait quelques tests avec JNI, et j'ai été obligé d'utiliser l'option -Wl,--kill-at lors de la génération de la DLL :

Code:

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gcc -shared -Wl,--kill-at -o jnidll.dll TestJNI.o

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:arrow: C'est propre à Windows et au mode d'appel stdcall qui rajoute un suffixe sur les noms de fonctions, ce qui fait que JNI ne les reconnait pas. Cette option permet d'éviter cela...

Source : --kill-at

a++

Super, ça fonctionne.
Je ne suis pas une brutasse en compilation C/C++, mon travail m'a orienté vers d'autres langages.
Votre réponse me fait gagner du temps. J'allais chercher un utilitaire pour décortiquer la DLL créée afin de m'assurer de la présence des méthodes implémentées, je serais tombé sur ce constat, et je serais revenu pour embêter pour savoir d'où ça pouvait provenir.

merci beaucoup adiGuba