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Diffstat (limited to 'README.md')
-rw-r--r-- | README.md | 53 |
1 files changed, 39 insertions, 14 deletions
@@ -15,7 +15,7 @@ declared by application or other plugins. Also a plugin can define extension poi Features/Benefits ------------------- With PF4J you can easily transform a monolithic java application in a modular application. -PF4J is an open source (Apache license) lightweight (around __50 KB__) plugin framework for java, with minimal dependencies (only slf4j-api) and very extensible (see PluginDescriptorFinder and ExtensionFinder). +PF4J is an open source (Apache license) lightweight (around __50 KB__) plugin framework for java, with minimal dependencies (only slf4j-api) and very extensible (see `PluginDescriptorFinder` and `ExtensionFinder`). Practically PF4J is a microframework and the aim is to keep the core simple but extensible. I try to create a little ecosystem (extensions) based on this core with the help of the comunity. For now are available these extensions: @@ -39,11 +39,15 @@ Components Any java interface or abstract class can be marked as an extension point (implements `ExtensionPoint` interface). - **Extension** is an implementation of an extension point. It's a java annotation on a class. +**PLUGIN** = a container for **EXTENSION POINTS** and **EXTENSIONS** + lifecycle methods (start, stop, delete) + +A **PLUGIN** is similar with a **MODULE** from other systems. If you don't need lifecycle methods (hook methods for start, stop, ...) you are not forced to supply a plugin class (the `PluginClass` property from the plugin descriptor is optional). You only need to supply some description of plugin (id, version, author, ...) for a good tracking (your application want to know who supplied the extensions or extensions points). + How to use ------------------- It's very simple to add pf4j in your application. -Define an extension point in your application using **ExtensionPoint** interface marker: +Define an extension point in your application/plugin using **ExtensionPoint** interface marker: ```java public interface Greeting extends ExtensionPoint { @@ -53,28 +57,49 @@ public interface Greeting extends ExtensionPoint { } ``` -Create a plugin that contribute with an extension: +Create an extension using `@Extension` annotation: ```java +@Extension +public static class WelcomeGreeting implements Greeting { + + public String getGreeting() { + return "Welcome"; + } + +} +``` + +Create (it's optional) a `Plugin` class if you are interested for plugin's lifecycle events (start, stop, ...): + +```java public class WelcomePlugin extends Plugin { public WelcomePlugin(PluginWrapper wrapper) { super(wrapper); - } - @Extension - public static class WelcomeGreeting implements Greeting { - - public String getGreeting() { - return "Welcome"; - } + // you can use "wrapper" to have access to the plugin context (plugin manager, descriptor, ...) + } + @Override + public void start() { + System.out.println("WelcomePlugin.start()"); } + @Override + public void stop() { + System.out.println("WelcomePlugin.stop()"); + } + + @Override + public void delete() { + System.out.println("WelcomePlugin.delete()"); + } + } ``` -In above code I created a plugin that comes with one extension for the `Greeting` extension point. +In above code I created a plugin (welcome) that comes with one extension for the `Greeting` extension point. You can distribute you plugin as a jar file (the simple solution). In this case add the plugin's metadata in `MANIFEST.MF` file of jar: @@ -91,8 +116,8 @@ Plugin-Provider: Decebal Suiu Plugin-Version: 0.0.1 ``` -In above manifest I described a plugin with id `welcome-plugin`, with class `org.pf4j.demo.welcome.WelcomePlugin`, with version `0.0.1` and with dependencies -to plugins `x, y, z`. +In above manifest I described a plugin with id `welcome-plugin` (mandatory), with class `org.pf4j.demo.welcome.WelcomePlugin` (optional), with version `0.0.1` (mandatory) and with dependencies +to plugins `x, y, z` (optional). Now you can play with plugins and extensions in your code: @@ -101,7 +126,7 @@ public static void main(String[] args) { ... // create the plugin manager - PluginManager pluginManager = new DefaultPluginManager(); + PluginManager pluginManager = new DefaultPluginManager(); // or "new JarPluginManager()" // start and load all plugins of application pluginManager.loadPlugins(); |