src/main/java/org/apache/bsf/util/BSFClassLoader.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
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(final String name, final 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 (final ClassNotFoundException e) {
                // nope
            }
            try {
                final byte[] data = loadClassData(name);
                c = defineClass(name, data, 0, data.length);
                cache.put(name, c);
            } catch (final Exception e) {
                e.printStackTrace();
                throw new ClassNotFoundException("unable to resolve class '" + name + "'");
            }
        }
        if (resolve) {
            resolveClass(c);
        }
        return c;
    }

    private byte[] loadClassData(final String name) throws Exception {
        final String fileName = tempDir + File.separatorChar + name + ".class";
        final FileInputStream fi = new FileInputStream(fileName);
        final byte[] data = new byte[fi.available()];
        fi.read(data);
        fi.close();
        return data;
    }

    public void setTempDir(final String tempDir) {
        this.tempDir = tempDir;
    }
}