MentaContainer

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package org.mentacontainer;
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/**
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 * A very simple container that provides:
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 * <ul>
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 *   <li> Bean instantiation (duh!)</li>
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 *   <li> Constructor injection for bean setup</li>
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 *   <li> Setter injection for bean setup</li>
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 *   <li> Wiring based on name and type</li>
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 *   <li> Scopes: Singleton and ThreadLocal</li>
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 *   <li> Wiring of external beans with the beans configured in this container</li>
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 *   <li> Annotation and XML free (programmatic configuration is the way to go!)
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 * </ul>
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 *
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 * It does not get much simpler than that.
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 *
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 * @author sergio.oliveira.jr@gmail.com
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 *
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 */
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public interface Container {
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        /**
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         * Get an instance from the container.
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         *
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         * The instance will be fully initialized (constructor and/or setters) and fully wired.
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         *
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         * @param key The key representing the bean to return. The name of the bean in the container.
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         * @return The fully initialized and wired bean.
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         */
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        public <T> T get(String key);
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        public Class<? extends Object> getType(String key);
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        /**
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         * Configure a bean to be returned with the given implementation when {@link #get(String)} is called.
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         *
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         * @param key The key representing the bean to return. The name of the bean in the container.
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         * @param klass The class used to instantiate the bean, in other words, its implementation.
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         * @param scope The scope of the component.
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         * @return The component created as a ConfigurableComponent. (Fluent API)
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         * @see Scope
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         */
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        public ConfigurableFactory ioc(String key, Class<? extends Object> klass, Scope scope);
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        /**
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         * Same as {@link #ioc(String, Class, Scope)} except that it assumes
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         * there is no scope (Scope.NONE).
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         *
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         * @param key
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         * @param klass
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         * @return The component created as a ConfigurableComponent. (Fluent API)
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         * @see Scope
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         */
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        public ConfigurableFactory ioc(String key, Class<?extends Object> klass);
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        /**
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         * Set up IoC based on the factory passed. The scope assumed is NONE.
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         *
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         * @param key The key representing the bean to return. The name of the bean in the container.
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         * @param factory The component for the IoC.
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         * @return The component passed as a parameter.
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         * @see Factory
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         */
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        public Factory ioc(String key, Factory factory);
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        /**
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         * Set up IoC based on the component passed. Specify the scope of the component.
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         *
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         * @param key The key representing the bean to return. The name of the bean in the container.
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         * @param component The component for the IoC.
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         * @param scope The scope used by the component.
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         * @return The component passed as a parameter.
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         * @see Factory
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         * @see Scope
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         */
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        public Factory ioc(String key, Factory component, Scope scope);
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        /**
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         * Configure a bean dependency to be auto-wired by the container. In general you want the
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         * type of the dependency to be an interface, for loosely couple dependencies. It works like that:<br/><br/>
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         *
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         * Whenever the container returns a bean, it checks to see if it has a property named <i>property</i>
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         * and if the type of the property is <i>klass</i>. If it does, then it looks for a bean named
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         * <i>source</i> and injects it inside the first bean it is returning. This approach is recursive
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         * so all properties are checked up the class hierarchy, until it reaches Object.
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         *
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         * @param property a bean property that will require another bean, in other words, the required
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         *                                 bean will be injected in the property of the bean been requested from the container. (auto-wiring by name)
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         * @param klass the type of the dependency, in other words, the type of the auto-wiring. (auto-wiring by type)
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         * @param source The dependency itself, coming from the container as well, in other words, the bean that will be injected in the original bean
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         * @return The container itself. (Fluent API)
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         */
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        public SetterDependency autowireBySetter(String property);
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        /**
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         * Same as {@link #wire(String, Class, String)} except that it assumes that the property name will be the source name, in other words,
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         * the property name is the same as the bean name that will be injected as the dependency.
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         *
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         * @param property
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         * @param klass
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         * @return The container itself. (Fluent API)
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         */
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        public SetterDependency autowireBySetter(String property, String source);
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        /**
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         * Setup a dependency.
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         *
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         * @param dependency The dependency to setup
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         * @return The dependency itself. (Fluent API)
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         * @see Dependency
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         */
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        //public Dependency autowireByConstructor(Class<? extends Object> type, String source);
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        /**
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         * Take a given bean and populate its properties with other beans coming from this container. Perhaps you can call this auto-wiring.
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         * You basically checking properties of the given bean and looking for values (by name and type!) inside the container. And injecting
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         * in the given bean, in other words, populating it.
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         *
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         * @param bean The bean to be populated with other beans from the container.
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         * @return The container itself. (Fluent API)
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         */
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        public Container populate(Object bean);
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        /**
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         * Check whether the container currently has a value for this key. For example,
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         * if it is a singleton AND someone has requested it, the container will have it cached.
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         * The method is useful to check for an instance without forcing her creation.
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         *
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         * @param key The key representing the bean inside the container.
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         * @return true if the container has an instance cached in the scope for this key
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         */
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        public boolean check(String key);
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        /**
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         * Clear all cached instances for that scope. If you have a thread-pool for example you will
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         * want to clear the THREAD scope when your thread is returned to the pool. Because you have a thread
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         * pool you will have the SAME thread handling different requests and each request will need its own instances
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         * from the container. Therefore, each time you are done with a thread and it is returned to your thread-pool
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         * you can call clear to release the instances allocated and cached by the container. A web container and/or framework
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         * can use this feature to implement a REQUEST scope which is nothing more than the THREAD scope with clear. If the web
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         * container was not using a thread-pool, the THREAD scope would be equal to the REQUEST scope as each request would
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         * always be handled by a different thread.
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         *  
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         * It does not make sense to clear a NONE scope (the method returns doing nothing). You can clear a SINGLETON scope if necessary.
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         *
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         * @param scope The scope to be cleared.
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         */
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        public void clear(Scope scope);
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        /**
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         * Clear a single key from cache and return the instance that was cached.
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         *
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         * @param key The key representing the bean inside the container.
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         * @return The value that was cached and it is not anymore (was cleared) or null if nothing was cleared
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         */
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        public <T> T clear(String key);
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}