类的类别顶级类，内嵌类、内部类、本地类、内名类

// There are five kinds of classes (or interfaces):
// a) Top level classes
// b) Nested classes (static member classes)
// c) Inner classes (non-static member classes)
// d) Local classes (named classes declared within a method)
// e) Anonymous classes

在看自动装配类的如何扫描拥有的注解的时候，发现了这一段，对类进行了区分，包括 顶级类，内嵌类（静态成员类）、内部类（非静态成员类）、本地类（使用方法名声明的类）、内名类
源码位置

public final class Class<T> implements java.io.Serializable,
                              GenericDeclaration,
                              Type,
                              AnnotatedElement {
    @CallerSensitive
    public Class<?> getEnclosingClass() throws SecurityException {
        // There are five kinds of classes (or interfaces):
        // a) Top level classes
        // b) Nested classes (static member classes)
        // c) Inner classes (non-static member classes)
        // d) Local classes (named classes declared within a method)
        // e) Anonymous classes


        // JVM Spec 4.8.6: A class must have an EnclosingMethod
        // attribute if and only if it is a local class or an
        // anonymous class.
        EnclosingMethodInfo enclosingInfo = getEnclosingMethodInfo();
        Class<?> enclosingCandidate;

        if (enclosingInfo == null) {
            // This is a top level or a nested class or an inner class (a, b, or c)
            enclosingCandidate = getDeclaringClass();
        } else {
            Class<?> enclosingClass = enclosingInfo.getEnclosingClass();
            // This is a local class or an anonymous class (d or e)
            if (enclosingClass == this || enclosingClass == null)
                throw new InternalError("Malformed enclosing method information");
            else
                enclosingCandidate = enclosingClass;
        }

        if (enclosingCandidate != null)
            enclosingCandidate.checkPackageAccess(
                    ClassLoader.getClassLoader(Reflection.getCallerClass()), true);
        return enclosingCandidate;
    }
}