| CharsetMapper | Utility class that attempts to map from a Locale to the corresponding
 character set to be used for interpreting input text (or generating
 output text) when the Content-Type header does not include one. | 
| ConcurrentDateFormat | Deprecated. | 
| ContextName | Utility class to manage context names so there is one place where the
 conversions between baseName, path and version take place. | 
| CustomObjectInputStream | Custom subclass of ObjectInputStreamthat loads from the
 class loader for this web application. | 
| DOMWriter | A DOM writer optimised for use by WebDAV. | 
| ErrorPageSupport | Provides support for tracking per exception type and per HTTP status code
 error pages. | 
| Extension | Utility class that represents either an available "Optional Package"
 (formerly known as "Standard Extension") as described in the manifest
 of a JAR file, or the requirement for such an optional package. | 
| ExtensionValidator | Ensures that all extension dependencies are resolved for a WEB application
 are met. | 
| Introspection | Provides introspection utilities that either require knowledge of Tomcat
 internals or are solely used by Tomcat internals. | 
| IOTools | Contains commonly needed I/O-related methods | 
| LifecycleBase |  | 
| LifecycleMBeanBase |  | 
| ManifestResource | Representation of a Manifest file and its available extensions and
  required extensions | 
| NetMask | A class representing a CIDR netmask. | 
| NetMaskSet | This class maintains a Set of NetMask objects and allows to check if a given IP address is matched by any of the
 NetMasks, making it easy to create Allow and Deny lists of CIDR networks and hosts. | 
| ParameterMap<K,V> | Implementation of java.util.Map that includes a
 lockedproperty. | 
| RequestUtil | General purpose request parsing and encoding utility methods. | 
| ResourceSet<T> | Extended implementation of HashSet that includes a
 lockedproperty. | 
| ServerInfo | Simple utility module to make it easy to plug in the server identifier
 when integrating Tomcat. | 
| SessionConfig |  | 
| SessionIdGeneratorBase |  | 
| StandardSessionIdGenerator |  | 
| Strftime | Converts dates to strings using the same format specifiers as strftime
 Note: This does not mimic strftime perfectly. | 
| TimeBucketCounter | This class maintains a thread safe hash map that has timestamp-based buckets followed by a string for a key, and a
 counter for a value. each time the increment() method is called it adds the key if it does not exist, increments its
 value and returns it. a maintenance thread cleans up keys that are prefixed by previous timestamp buckets. | 
| TLSUtil |  | 
| TomcatCSS |  | 
| ToStringUtil | Utility class used to help generate return values for calls to
 Object.toString(). | 
| URLEncoder | This class is very similar to the java.net.URLEncoder class. | 
| XMLWriter | XMLWriter helper class. |