Package com.google.inject.internal

Class BytecodeGen

java.lang.Object

com.google.inject.internal.BytecodeGen

public final class BytecodeGen
extends Object

Utility methods for runtime code generation and class loading. We use this stuff for faster reflection, method interceptors and to proxy circular dependencies.

When loading classes, we need to be careful of:

• Memory leaks. Generated classes need to be garbage collected in long-lived applications. Once an injector and any instances it created can be garbage collected, the corresponding generated classes should be collectable.
• Visibility. Containers like OSGi use class loader boundaries to enforce modularity at runtime.

For each generated class, there's multiple class loaders involved:

• The related class's class loader. Every generated class services exactly one user-supplied class. This class loader must be used to access members with protected and package visibility.
• Guice's class loader.
• Our bridge class loader. This is a child of the user's class loader. It selectively delegates to either the user's class loader (for user classes) or the Guice class loader (for internal classes that are used by the generated classes). This class loader that owns the classes generated by Guice.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	BytecodeGen.BridgeClassLoader	Loader for Guice-generated classes.
private static class	BytecodeGen.SystemBridgeHolder
static enum	BytecodeGen.Visibility	The required visibility of a user's class from a Guice-generated class.

Field Summary

Fields

Modifier and Type	Field	Description
private static final String	CGLIB_PACKAGE
private static final com.google.common.cache.LoadingCache<ClassLoader,ClassLoader>	CLASS_LOADER_CACHE	Weak cache of bridge class loaders that make the Guice implementation classes visible to various code-generated proxies of client classes.
(package private) static final ClassLoader	GUICE_CLASS_LOADER
(package private) static final String	GUICE_INTERNAL_PACKAGE	ie.
(package private) static final Logger	logger

Constructor Summary

Constructors

Constructor	Description
BytecodeGen()

Method Summary

Modifier and Type	Method	Description
private static ClassLoader	canonicalize(ClassLoader classLoader)	Attempts to canonicalize null references to the system class loader.
static ClassLoader	getClassLoader(Class<?> type)	Returns the class loader to host generated classes for type.
private static ClassLoader	getClassLoader(Class<?> type, ClassLoader delegate)

Methods inherited from class java.lang.Object

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

Field Details

logger

static final Logger logger

GUICE_CLASS_LOADER

static final ClassLoader GUICE_CLASS_LOADER

GUICE_INTERNAL_PACKAGE

static final String GUICE_INTERNAL_PACKAGE

ie. "com.google.inject.internal"

CGLIB_PACKAGE

private static final String CGLIB_PACKAGE

See Also:

• Constant Field Values

CLASS_LOADER_CACHE

private static final com.google.common.cache.LoadingCache<ClassLoader,ClassLoader> CLASS_LOADER_CACHE

Weak cache of bridge class loaders that make the Guice implementation classes visible to various code-generated proxies of client classes.

Constructor Details

BytecodeGen

public BytecodeGen()

Method Details

canonicalize

private static ClassLoader canonicalize(ClassLoader classLoader)

Attempts to canonicalize null references to the system class loader. May return null if for some reason the system loader is unavailable.

getClassLoader

public static ClassLoader getClassLoader(Class<?> type)

Returns the class loader to host generated classes for type.

getClassLoader

private static ClassLoader getClassLoader(Class<?> type,
 ClassLoader delegate)