on java native method?

u can't directly call the dll from java i think u need a bridge to invoke a methods from dll
try refering
www.linar.com
cheers
RJ

Try giving full file name

ie.,System.loadLibrary("advapi32.dll");


 

Hi lilugun

Why can't u use System Property to know the current user name

Why do u need a native libraries to do that


Shyam

Follow the comment from rjackman, you need a wrapper do access existing DLL's.
Try javah -jni on your class you will get a C-header file
and see the signature (Name of the native method) searched from the JVM.
Write a native method with the name you got from the header taking the input parms from Java translate them to C parms.
Call the GetUserName(...) method and return the translated result to the JVM.

Create your own dll with a C compiler .
Load this library instead of advapi32.dll
Ensure both dll's the new one and advapi32.dll are in the PATH and run your Java application.

More information and examples you will find for example at
http://java.sun.com/docs/books/tutorial/native1.1/index.html

cheers
jf

I mean if I got a *.dll file, and I know it contains some functions, how can I use the fountions aa a native method?

Hi lilugun,

I beleive I am very near to solve the problem. The theory says the native methods should be ended with semicolon in the body of the method.
Now in your case the method acts like abstract without implementation. So everything is fine just change your native methods put the semicolon into the block or body of the method.
Try this as I don't have Jdk with me to try at the moment.

Thanks
ImrML

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Lilugun,
What you are writing may be correct as my suggestion doesn't work. The exception raised may be due to the type mismatch.

Sorry, for wrong suggestions.

Thanks
Imrml

Mr ImrML
What happened
Why do u post so many messages

Shyam

Please me useful advice!
I mean if I got a *.dll file, and I know it contains some functions, how can I use the fountions as
a native method?
 IN VISUAL BASIC we know we can use any *.DLL if we know the function we can use it freely!
 IN JAVA ,can we made it?

liluqun,

as rjackman said before, you need a wrapper-DLL.

Why?
public class Frame1 extends JFrame {
 
 // the native method
 public native long GetUserNameW(String s,long n);
 // some more code for the class
 ...
 }

If you run you will get the name of the method in your native dll in your example:
JNIEXPORT jlong JNICALL Java_Frame1_GetUserName   (JNIEnv *, jobject, jstring, jlong);

I'm sure there will be no method inside advapi32.dll with
this name.

you need a piece of C-code which will do the mapping:

#include <Frame1.h> // output from cmd  javah -jni Frame1
// the wrapper method
JNIEXPORT jlong JNICALL Java_Frame1_GetUserName   (JNIEnv * env, jobject obj, jstring jstr , jlong myLong)
{
 char buf[1024]; // buffer for converting jstring to C
 long retValue = -1;
 const char *str = (*env)->GetStringUTFChars(env,jstr,0);
 retValue = GetUserName(str, myLong);
 // releasing the str/jstr pair
 (*env)->ReleaseStringUTFChars(env,jstr,str);
 return retValue;
}

Compile and Link this file and load the resulting DLL.

Hope this helps
jf

liluqun,

as rjackman said before, you need a wrapper-DLL.

Why?
public class Frame1 extends JFrame {
 
 // the native method
 public native long GetUserNameW(String s,long n);
 // some more code for the class
 ...
 }

If you run you will get the name of the method in your native dll in your example:
JNIEXPORT jlong JNICALL Java_Frame1_GetUserName   (JNIEnv *, jobject, jstring, jlong);

I'm sure there will be no method inside advapi32.dll with
this name.

you need a piece of C-code which will do the mapping:

#include <Frame1.h> // output from cmd  javah -jni Frame1
// the wrapper method
JNIEXPORT jlong JNICALL Java_Frame1_GetUserName   (JNIEnv * env, jobject obj, jstring jstr , jlong myLong)
{
 char buf[1024]; // buffer for converting jstring to C
 long retValue = -1;
 const char *str = (*env)->GetStringUTFChars(env,jstr,0);
 retValue = GetUserName(str, myLong);
 // releasing the str/jstr pair
 (*env)->ReleaseStringUTFChars(env,jstr,str);
 return retValue;
}

Compile and Link this file and load the resulting DLL.

Hope this helps
jf

liluqun,

as rjackman said before, you need a wrapper-DLL.

Why?
public class Frame1 extends JFrame {
 
 // the native method
 public native long GetUserNameW(String s,long n);
 // some more code for the class
 ...
 }

If you run you will get the name of the method in your native dll in your example:
JNIEXPORT jlong JNICALL Java_Frame1_GetUserName   (JNIEnv *, jobject, jstring, jlong);

I'm sure there will be no method inside advapi32.dll with
this name.

you need a piece of C-code which will do the mapping:

#include <Frame1.h> // output from cmd  javah -jni Frame1
// the wrapper method
JNIEXPORT jlong JNICALL Java_Frame1_GetUserName   (JNIEnv * env, jobject obj, jstring jstr , jlong myLong)
{
 char buf[1024]; // buffer for converting jstring to C
 long retValue = -1;
 const char *str = (*env)->GetStringUTFChars(env,jstr,0);
 retValue = GetUserName(str, myLong);
 // releasing the str/jstr pair
 (*env)->ReleaseStringUTFChars(env,jstr,str);
 return retValue;
}

Compile and Link this file and load the resulting DLL.

Hope this helps
jf

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