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package com.bioxpr.loader;
public class JarClassLoader extends MultiClassLoader
{
private JarResources jarResources;
public JarClassLoader (String jarName)
{
// Create the JarResource and suck in the jar file.
jarResources = new JarResources (jarName);
}
protected byte[] loadClassBytes (String className)
{
// Support the MultiClassLoader's class name munging facility.
className = formatClassName (className);
// Attempt to get the class data from the JarResource.
return (jarResources.getResource (className));
}
}
package com.bioxpr.loader;
import java.util.Hashtable;
/**
* A simple test class loader capable of loading from
* multiple sources, such as local files or a URL.
*
* This class is derived from an article by Chuck McManis
* http://www.javaworld.com/javaworld/jw-10-1996/indepth.src.html
* with large modifications.
*
* Note that this has been updated to use the non-deprecated version of
* defineClass() -- JDM.
*
* @author Jack Harich - 8/18/97
* @author John D. Mitchell - 99.03.04
*/
public abstract class MultiClassLoader extends ClassLoader {
// ---------- Fields --------------------------------------
private Hashtable classes = new Hashtable();
private char classNameReplacementChar;
protected boolean monitorOn = false;
protected boolean sourceMonitorOn = true;
// ---------- Initialization ------------------------------
public MultiClassLoader() {
}
// ---------- Superclass Overrides ------------------------
/**
* This is a simple version for external clients since they
* will always want the class resolved before it is returned
* to them.
*/
@SuppressWarnings("unchecked")
public Class loadClass(String className) throws ClassNotFoundException {
return (loadClass(className, true));
}
// ---------- Abstract Implementation ---------------------
@SuppressWarnings("unchecked")
public synchronized Class loadClass(String className,
boolean resolveIt) throws ClassNotFoundException {
Class result;
byte[] classBytes;
monitor(">> MultiClassLoader.loadClass(" + className + ", " + resolveIt + ")");
//----- Check our local cache of classes
result = (Class)classes.get(className);
if (result != null) {
monitor(">> returning cached result.");
return result;
}
//----- Check with the primordial class loader
try {
result = super.findSystemClass(className);
monitor(">> returning system class (in CLASSPATH).");
return result;
} catch (ClassNotFoundException e) {
monitor(">> Not a system class.");
}
//----- Try to load it from preferred source
// Note loadClassBytes() is an abstract method
classBytes = loadClassBytes(className);
if (classBytes == null) {
throw new ClassNotFoundException();
}
//----- Define it (parse the class file)
result = defineClass(className, classBytes, 0, classBytes.length);
if (result == null) {
throw new ClassFormatError();
}
//----- Resolve if necessary
if (resolveIt) resolveClass(result);
// Done
classes.put(className, result);
monitor(">> Returning newly loaded class.");
return result;
}
// ---------- Public Methods ------------------------------
/**
* This optional call allows a class name such as
* "COM.test.Hello" to be changed to "COM_test_Hello",
* which is useful for storing classes from different
* packages in the same retrival directory.
* In the above example the char would be '_'.
*/
public void setClassNameReplacementChar(char replacement) {
classNameReplacementChar = replacement;
}
// ---------- Protected Methods ---------------------------
protected abstract byte[] loadClassBytes(String className);
protected String formatClassName(String className) {
if (classNameReplacementChar == '\u0000') {
// '/' is used to map the package to the path
return className.replace('.', '/') + ".class";
} else {
// Replace '.' with custom char, such as '_'
return className.replace('.',
classNameReplacementChar) + ".class";
}
}
protected void monitor(String text) {
if (monitorOn) print(text);
}
// --- Std
protected static void print(String text) {
System.out.println(text);
}
} // End class |
