This module holds utilities used in other libraries of the toolkit. Check the packages' documentation for more details. You can find a quick recap of the main features in the sections below.
Install the Dependency¶
This module is not meant to be imported directly. It will be included by using any other part of the toolkit. However, if you only want to use the utilities, logging, etc. (i.e., for a desktop application), you can import it with the following code:
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JVM information and other useful utilities.
Classpath URLs in native images¶
To use the 'classpath' URL scheme on GraalVM native images, the
native-image command requires to
add the Classpath handler manually with the
Flags (System Properties)¶
- DISABLE_CHECKS: set to true to disable some checks in order to shave a few ms. in production. Do not enable it in application development and turn it on only when the application is extensively tested.
Provide general utilities to attach many handlers to be applied on events processing. Events can be of any type.
Handlers may or may not be applied to certain events at runtime based on rules provided as a predicate (function).
If an event doesn't match a handler's predicate, that handler is ignored, and the next one will be processed.
When a handler's predicate returns true, its callback will be called. That block will process the event, and return a modified copy with the changes.
The callback block will decide if subsequent handler's will be evaluated by calling the next handler
next method is not called, the handlers defined later won't be evaluated).
There are types of handlers like 'After' y 'Before' that call
next as part as their operation
discharging the user of doing so.
The events are passed to handlers' callbacks wrapped in a 'context'. The context can also pass
information among handlers in the
attributes field. And store an exception if it is thrown in a
previous handler processing.
Types of handlers:
- On Handler: the callback is executed before calling the remaining handlers.
nextis called after the callback.
- After Handler: the predicate is evaluated after the remaining handlers return, and the callback is
nextis called before the callback
- Filter Handler:
nextis not called by this handler, its callback is responsible for doing so if needed.
- Chain Handler: this handler contains a list of handlers inside.
IMPORTANT: the order is NOT the order, it is the depth. Handlers are not linked, they are NESTED.
next() method passes control to the next level.
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Is really this execution:
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Provides a logging management capabilities abstracting the application from logging libraries.
The following code block shows the most common use cases for the Logger class:
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By default, Hexagon uses the Java Util Logging logging library, you can use any of its implementations by just adding another logging adapter as a dependency. Below you can see some alternatives:
Logging implementation for Java logging module. This is the default implementation.
Media types definitions and constants for default media types.
Cryptography and key stores utilities.