Java interpreter replacement
/*
* Copyright 2000-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
/**
* Java interpreter replacement, i.e., wrapper that uses its own ClassLoader to
* modify/generate classes as they're requested. You can take this as a template
* for your own applications.<br>
* Call this wrapper with
*
*
* @version $Id: JavaWrapper.java 386056 2006-03-15 11:31:56Z tcurdt $
* @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
* @see ClassLoader
*/
public class JavaWrapper {
private java.lang.ClassLoader loader;
private static java.lang.ClassLoader getClassLoader() {
String s = System.getProperty("bcel.classloader");
if ((s == null) || "".equals(s)) {
s = "org.apache.bcel.util.ClassLoader";
}
try {
return (java.lang.ClassLoader) Class.forName(s).newInstance();
} catch (Exception e) {
throw new RuntimeException(e.toString());
}
}
public JavaWrapper(java.lang.ClassLoader loader) {
this.loader = loader;
}
public JavaWrapper() {
this(getClassLoader());
}
/**
* Runs the main method of the given class with the arguments passed in argv
*
* @param class_name
* the fully qualified class name
* @param argv
* the arguments just as you would pass them directly
*/
public void runMain(String class_name, String[] argv) throws ClassNotFoundException {
Class cl = loader.loadClass(class_name);
Method method = null;
try {
method = cl.getMethod("main", new Class[] { argv.getClass() });
/*
* Method main is sane ?
*/
int m = method.getModifiers();
Class r = method.getReturnType();
if (!(Modifier.isPublic(m) && Modifier.isStatic(m)) || Modifier.isAbstract(m)
|| (r != Void.TYPE)) {
throw new NoSuchMethodException();
}
} catch (NoSuchMethodException no) {
System.out.println("In class " + class_name
+ ": public static void main(String[] argv) is not defined");
return;
}
try {
method.invoke(null, new Object[] { argv });
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* Default main method used as wrapper, expects the fully qualified class name
* of the real class as the first argument.
*/
public static void main(String[] argv) throws Exception {
/*
* Expects class name as first argument, other arguments are by-passed.
*/
if (argv.length == 0) {
System.out.println("Missing class name.");
return;
}
String class_name = argv[0];
String[] new_argv = new String[argv.length - 1];
System.arraycopy(argv, 1, new_argv, 0, new_argv.length);
JavaWrapper wrapper = new JavaWrapper();
wrapper.runMain(class_name, new_argv);
}
}