LibraryLoader.java
/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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 androidx.media3.common.util;
import java.util.Arrays;
/** Configurable loader for native libraries. */
@UnstableApi
public abstract class LibraryLoader {
private static final String TAG = "LibraryLoader";
private String[] nativeLibraries;
private boolean loadAttempted;
private boolean isAvailable;
/**
* @param libraries The names of the libraries to load.
*/
public LibraryLoader(String... libraries) {
nativeLibraries = libraries;
}
/**
* Overrides the names of the libraries to load. Must be called before any call to {@link
* #isAvailable()}.
*/
public synchronized void setLibraries(String... libraries) {
Assertions.checkState(!loadAttempted, "Cannot set libraries after loading");
nativeLibraries = libraries;
}
/** Returns whether the underlying libraries are available, loading them if necessary. */
public synchronized boolean isAvailable() {
if (loadAttempted) {
return isAvailable;
}
loadAttempted = true;
try {
for (String lib : nativeLibraries) {
loadLibrary(lib);
}
isAvailable = true;
} catch (UnsatisfiedLinkError exception) {
// Log a warning as an attempt to check for the library indicates that the app depends on an
// extension and generally would expect its native libraries to be available.
Log.w(TAG, "Failed to load " + Arrays.toString(nativeLibraries));
}
return isAvailable;
}
/**
* Should be implemented to call {@code System.loadLibrary(name)}.
*
* <p>It's necessary for each subclass to implement this method because {@link
* System#loadLibrary(String)} uses reflection to obtain the calling class, which is then used to
* obtain the class loader to use when loading the native library. If this class were to implement
* the method directly, and if a subclass were to have a different class loader, then loading of
* the native library would fail.
*
* @param name The name of the library to load.
*/
protected abstract void loadLibrary(String name);
}