Re: [cdt-debug-dev] question on how cdt make JNI call?

[Alex Chapiro <achapiro@xxxxxxx>]

First, verify native methods signature in C code. It should be exactly 
the same as javah generated.  In your case they I wrong I suppose. You 
can see how valid names look like in spawner.dll sources. Your names 
miss package signature. It should be:

Java_org_eclipse_cdt_utils_spawner_SpawnerOutputStream_greeting(...)

I guess you've got wrong header because you ran javah from the wrong 
working directory.

Regards,

Alex.

Yan Chen wrote:

> Hi,all!!!
>
> I know this question maybe should not be asked in this mailing list, but
> my question is somehow related to CDT codes. So any help is
> appreciated!!!
>
> My plugin need to load dynamic library and make JNI call, but until now
> I do not have any luck. Under terminal I can load .so and make JNI call
> without any problem, but I have no idea why my eclipse plugin can not
> make JNI call(by using system.load() or system.loadLibrary()).  To
> access native libraries in eclipse Do I need to set up correctly the
> path in the plugin.xml? and how?
>
> By reading CDT code, I found CDT also make JNI call, so I did a test as
> follows:
>
> I first made libSpawnerOutputStream.so and then I put it in the
> directory org.eclipse.cdt.core.linux/os/linux/x86 where libspawner.so
> is. Then I added my stuff in the class SpawnerOutputStream as follows:
>
> public class SpawnerOutputStream extends OutputStream {
>     
>       
> 	public void write(byte[] b, int off, int len) throws IOException
> {
> 	        
> 		write0(fd, tmpBuf, len);
>
>                /*****My stuff**********/
> 		greeting();
>                /*****My stuff**********/
> 	}
>
> 	private native int write0(int fd, byte[] b, int len) throws
> IOException;
> 	private native int close0(int fd);
>
>        /*****My stuff**********/
> 	public static native void greeting();
> 	/*****My stuff**********/
>        
>
> 	static {
> 		System.loadLibrary("spawner"); //$NON-NLS-1$
>
>                /*****My stuff**********/
> 		System.loadLibrary("SpawnerOutputStream");
>                /*****My stuff**********/
> 	}
>
> }
>
> But when I start debugging a c program, I got the following error:
>
> java.lang.UnsatisfiedLinkError: greeting
> 	at
> org.eclipse.cdt.utils.spawner.SpawnerOutputStream.greeting(Native
> Method)
> 	at
> org.eclipse.cdt.utils.spawner.SpawnerOutputStream.write(SpawnerOutputStr
> eam.java:50)
> 	at java.io.OutputStream.write(OutputStream.java:58)
> 	at org.eclipse.cdt.debug.mi.core.TxThread.run(TxThread.java:72)
>
> Could someone help me out? Thanks in advance!!!
>
> Johnny
>
>
>
>
> P.S. The following codes are for making .so file
>
> /* DO NOT EDIT THIS FILE - it is machine generated */
> #include <jni.h>
> /* Header for class SpawnerOutputStream */
>
> #ifndef _Included_SpawnerOutputStream
> #define _Included_SpawnerOutputStream
> #ifdef __cplusplus
> extern "C" {
> #endif
> /*
> * Class:     SpawnerOutputStream
> * Method:    greeting
> * Signature: ()V
> */
> JNIEXPORT void JNICALL Java_SpawnerOutputStream_greeting
>  (JNIEnv *, jclass);
>
> #ifdef __cplusplus
> }
> #endif
> #endif
>
>
> /**
> * @version 1.10 1997-07-01
> * @author Cay Horstmann
> */
>
> #include "SpawnerOutputStream.h"
> #include <stdio.h>
>
> JNIEXPORT void JNICALL Java_SpawnerOutputStream_greeting
>  (JNIEnv* env, jclass cl)
> {  printf("Hello world!\n");
> }
>
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