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.
  • 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:
    • 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)