BytecodeGen.java 文件源码

/**
 * Returns a FastClass proxy for invoking the given member or {@code null} if access rules 
 * disallow it.
 * 
 * <p>FastClass works by generating a type in the same package as the target {@code type}. This
 * may or may not work depending on the access level of the class/member. It breaks down into the
 * following cases depending on accessibility:
 * <ul>
 *   <li>Public: This always works since we can generate the type into the 
 *   {@link BridgeClassLoader} which ensures there are no versioning issues.
 *   <li>Package private and Protected: This works as long as:
 *   <ul> 
 *     <li>We can generate into the same classloader as the type.  This is not possible for JDK
 *     types which use the 'bootstrap' loader.
 *     <li>The classloader of the type has the same version of {@code FastClass} as we do.  This
 *     may be violated when running in OSGI bundles.
 *   </ul>
 *   <li>Private: This never works.
 * </ul>
 * 
 * If we are unable to generate the type, then we return null and callers should work around by
 * using normal java reflection.
 */
public static net.sf.cglib.reflect.FastClass newFastClassForMember(Class<?> type, Member member) {
  if (!new net.sf.cglib.core.VisibilityPredicate(type, false).evaluate(member)) {
    // the member cannot be indexed by fast class.  Bail out.
    return null;
  }

  boolean publiclyCallable = isPubliclyCallable(member);
  if (!publiclyCallable && !hasSameVersionOfCglib(type.getClassLoader())) {
    // The type is in a classloader with a different version of cglib and is not publicly visible
    // (so we can't use the bridge classloader to work around).  Bail out.
    return null;
  }
  net.sf.cglib.reflect.FastClass.Generator generator
      = new net.sf.cglib.reflect.FastClass.Generator();
  if (publiclyCallable) {
    // Use the bridge classloader if we can
    generator.setClassLoader(getClassLoader(type));
  }
  generator.setType(type);
  generator.setNamingPolicy(FASTCLASS_NAMING_POLICY);
  if (logger.isLoggable(Level.FINE)) {
    logger.fine("Loading " + type + " FastClass with " + generator.getClassLoader());
  }
  return generator.create();
}