Make doubley certain that the dll implements the function prototypes that
javah creates from your native class. I've had it were the library loaded
just fine but there was a name missmatch between the native methods and the
JNI functions and I recieved similar sort of runtime errors AFTER successful
load (was on Linux so I'll not say the SAME errors). It happened to me when
I changed the native class's package and javah changed the prototypes to
reflect that.
-----Original Message-----
From: Ryan Adrian [mailto:[EMAIL PROTECTED]]
Sent: Thursday, January 25, 2001 11:40 AM
To: '[EMAIL PROTECTED]'
Subject: JNI Servlet with Tomcat Problem
Hi,
I am using a servlet call to a C dll with JNI. I am using Windows NT4,
TOMCAT 3.2, jdk1.3, c dll. Below is my code....
#################################################
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class jniServlet2 extends HttpServlet {
public String myString = null;
public native String displayHelloWorld();
public void init() throws ServletException
{
try {
//System.load("d:\\work\\jni\\hello.dll");
System.loadLibrary("hello");
} catch(Exception e) {
System.err.println("error1-> " + e);
return;
} catch(Throwable e) {
System.err.println("error2->" + e);
return;
}
System.err.println("Successfully loaded DLL");
myString = new jniServlet2().displayHelloWorld();
}
public void doGet(HttpServletRequest request, HttpServletResponse
response)
throws IOException, ServletException
{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<body>");
out.println("<head>");
out.println("<title>Hello World!</title>");
out.println("</head>");
out.println("<body>");
out.println( myString );
out.println("</body>");
out.println("</html>");
}
}
#############################################
In the Tomcat console "Successfully loaded DLL" is printed. However, the
native method displayHelloWorld() terminates the code abnormally.
The error I'm receiving in the browser is an UnsatisfiedLinkError as
follows...
#################################################
Internal Servlet Error:
java.lang.UnsatisfiedLinkError: displayHelloWorld
at jniServlet2.displayHelloWorld(Native Method)
at jniServlet2.init(jniServlet2.java:34)
at javax.servlet.GenericServlet.init(GenericServlet.java:258)
at
org.apache.tomcat.core.ServletWrapper.doInit(ServletWrapper.java:317)
at org.apache.tomcat.core.Handler.init(Handler.java:215)
at
org.apache.tomcat.core.ServletWrapper.init(ServletWrapper.java:296)
at org.apache.tomcat.core.Handler.service(Handler.java:254)
at
org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
at
org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:79
7)
at
org.apache.tomcat.core.ContextManager.service(ContextManager.java:743)
at
org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpC
onnectionHandler.java:210)
at
org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)
at
org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:498)
at java.lang.Thread.run(Thread.java:484)
########################################################################
The code for the c dll Implemation is as follows....
#include <jni.h>
#include "HelloWorld.h"
#include <stdio.h>
#include <string.h>
JNIEXPORT jstring JNICALL Java_HelloWorld_displayHelloWorld
(JNIEnv *env, jobject obj)
{
jstring value;
char buf[40];
strcpy(buf,"HelloWorld");
value = (*env)->NewStringUTF(env,buf);
return value;
}
#########################################################
I've tried adding the dll path to the SYSTEM and USER path, and I've tried
the load() and loadLibrary() appraoches, but Tomcat is just not finding the
dll......
Can anyone please help......
Adrian.
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