bsfclassloader.java

Bean Scripting Framework (BSF)为在java应用中使用脚本语言

/*
 * Copyright 2004,2004 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.
 */

package org.apache.bsf.util;

import java.io.File;
import java.io.FileInputStream;
import java.util.Hashtable;

/**
 * This class loader knows to load a class from the tempDir dir
 * of the environment of the given manager. 
 * 
 * @author   Sanjiva Weerawarana
 */
class BSFClassLoader extends ClassLoader {
  Hashtable cache = new Hashtable ();
  String tempDir = ".";

  // note the non-public constructor - this is only avail within
  // this package.
  BSFClassLoader () {
  }
  public synchronized Class loadClass (String name, boolean resolve)
											   throws ClassNotFoundException {
	Class c = (Class) cache.get (name);
	if (c == null) {
	  // is it a system class
	  try {
	c = findSystemClass (name);
	cache.put (name, c);
	return c;
	  } catch (ClassNotFoundException e) {
	// nope
	  }
	  try {
	byte[] data = loadClassData (name);
	c = defineClass (name, data, 0, data.length);
	cache.put (name, c); 
	  } catch (Exception e) {
	e.printStackTrace ();
	throw new ClassNotFoundException ("unable to resolve class '" + 
					  name + "'");
	  }
	}
	if (resolve)
	  resolveClass (c); 
	return c;  
  }
  private byte[] loadClassData (String name) throws Exception {
	String fileName = tempDir + File.separatorChar + name + ".class";
	FileInputStream fi = new FileInputStream (fileName);
	byte[] data = new byte[fi.available ()];
	fi.read (data);
	fi.close();
	return data;
  }
  public void setTempDir (String tempDir) {
	this.tempDir = tempDir;
  }
}