net.bytebuddy.android

Class AndroidClassLoadingStrategy

java.lang.Object

net.bytebuddy.android.AndroidClassLoadingStrategy

All Implemented Interfaces:

ClassLoadingStrategy<ClassLoader>

Direct Known Subclasses:

AndroidClassLoadingStrategy.Injecting, AndroidClassLoadingStrategy.Wrapping

public abstract class AndroidClassLoadingStrategy
extends Object
implements ClassLoadingStrategy<ClassLoader>

A class loading strategy that allows to load a dynamically created class at the runtime of an Android application. For this, a DexClassLoader is used under the covers.

This class loader requires to write files to the file system which are then processed by the Android VM. It is not permitted by Android's security checks to store these files in a shared folder where they could be manipulated by a third application what would break Android's sandbox model. An example for a forbidden storage would therefore be the external storage. Instead, the class loading application must either supply a designated directory, such as by creating a directory using android.content.Context#getDir(String, int) with specifying android.content.Context#MODE_PRIVATE visibility for the created folder or by using the getCodeCacheDir directory which is exposed for Android API versions 21 or higher.

By default, this Android ClassLoadingStrategy uses the Android SDK's dex compiler in version 1.7 which requires the Java class files in version ClassFileVersion.JAVA_V6 as its input. This version is slightly outdated but newer versions are not available in Maven Central which is why this outdated version is included with this class loading strategy. Newer version can however be easily adapted by implementing the methods of a AndroidClassLoadingStrategy.DexProcessor to appropriately delegate to the newer dex compiler. In case that the dex compiler's API was not altered, it would even be sufficient to include the newer dex compiler to the Android application's build path while also excluding the version that ships with this class loading strategy. While most parts of the Android SDK's components are licensed under the Apache 2.0 license, please also note their terms and conditions.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AndroidClassLoadingStrategy.DexProcessor A dex processor is responsible for converting a collection of Java class files into a Android dex file.
static class	AndroidClassLoadingStrategy.Injecting An Android class loading strategy that injects types into the target class loader.
static class	AndroidClassLoadingStrategy.Wrapping An Android class loading strategy that creates a wrapper class loader that loads any type.

Nested classes/interfaces inherited from interface net.bytebuddy.dynamic.loading.ClassLoadingStrategy

ClassLoadingStrategy.Configurable<S extends ClassLoader>, ClassLoadingStrategy.Default, ClassLoadingStrategy.ForBootstrapInjection, ClassLoadingStrategy.ForJnaInjection, ClassLoadingStrategy.ForPreloadedTypes, ClassLoadingStrategy.ForUnsafeInjection, ClassLoadingStrategy.UsingLookup

Field Summary

Fields

Modifier and Type	Field and Description
protected File	privateDirectory A directory that is not shared with other applications to be used for storing generated classes and their processed forms.
protected RandomString	randomString A generator for random string values.

Fields inherited from interface net.bytebuddy.dynamic.loading.ClassLoadingStrategy

BOOTSTRAP_LOADER, NO_PROTECTION_DOMAIN

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AndroidClassLoadingStrategy(File privateDirectory, AndroidClassLoadingStrategy.DexProcessor dexProcessor) Creates a new Android class loading strategy that uses the given folder for storing classes.

Method Summary

Modifier and Type	Method and Description
protected abstract Map<TypeDescription,Class<?>>	doLoad(ClassLoader classLoader, Set<TypeDescription> typeDescriptions, File jar) Applies the actual class loading.
Map<TypeDescription,Class<?>>	load(ClassLoader classLoader, Map<TypeDescription,byte[]> types)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

privateDirectory

protected final File privateDirectory

A directory that is not shared with other applications to be used for storing generated classes and their processed forms.

randomString

protected final RandomString randomString

A generator for random string values.

Constructor Detail

AndroidClassLoadingStrategy

protected AndroidClassLoadingStrategy(File privateDirectory,
                                      AndroidClassLoadingStrategy.DexProcessor dexProcessor)

Creates a new Android class loading strategy that uses the given folder for storing classes. The directory is not cleared by Byte Buddy after the application terminates. This remains the responsibility of the user.

Parameters:

privateDirectory - A directory that is not shared with other applications to be used for storing generated classes and their processed forms.

dexProcessor - The dex processor to be used for creating a dex file out of Java files.

Method Detail

load

public Map<TypeDescription,Class<?>> load(@MaybeNull
                                          ClassLoader classLoader,
                                          Map<TypeDescription,byte[]> types)

Specified by:

load in interface ClassLoadingStrategy<ClassLoader>

doLoad

protected abstract Map<TypeDescription,Class<?>> doLoad(@MaybeNull
                                                        ClassLoader classLoader,
                                                        Set<TypeDescription> typeDescriptions,
                                                        File jar)
                                                 throws IOException

Applies the actual class loading.

Parameters:

classLoader - The target class loader.

typeDescriptions - Descriptions of the loaded types.

jar - A jar file containing the supplied types as dex files.

Returns:

A mapping of all type descriptions to their loaded types.

Throws:

IOException - If an I/O exception occurs.