1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.dexgen.util;
18
19import dalvik.system.DexClassLoader;
20
21/**
22 * Class used indirectly for loading generated dex classes. It allows the caller
23 * to obtain appropriate {@code DexClassLoader} instance, which can be then used for
24 * loading classes.
25 */
26public class DexClassLoaderHelper {
27
28    private static class DexClassLoaderHelperHolder {
29        private static final DexClassLoaderHelper INSTANCE = new DexClassLoaderHelper();
30    }
31
32    private DexClassLoaderHelper() {
33        // intentionally empty to disable direct instantiation
34    }
35
36    /**
37     * Returns the sole instance of {@code DexClassLoaderHelper}.
38     *
39     * @return dex {@code DexClassLoaderHelper} sole instance
40     */
41    public static DexClassLoaderHelper getInstance() {
42        return DexClassLoaderHelperHolder.INSTANCE;
43    }
44
45    /**
46     * Creates and returns DexClassLoader instance with its classpath
47     * set to {@code pathHolder}.
48     *
49     * @param pathHolder {@code non-null;} location of jar archive containing dex
50     * classes canned into a working PathHolder instance.
51     * @return dex class loader instance with its classpath set to location
52     * indicated by {@code pathHolder}
53     */
54    public ClassLoader getDexClassLoader(PathHolder pathHolder) {
55        ClassLoader myLoader = DexClassLoaderHelper.class.getClassLoader();
56        return new DexClassLoader(pathHolder.getJarFilePath(), pathHolder.getDirLocation(),
57                null, myLoader);
58    }
59}