org.apache.commons.configuration2.builder

## Class ReloadingFileBasedConfigurationBuilder<T extends FileBasedConfiguration>

- java.lang.Object
- - org.apache.commons.configuration2.builder.BasicConfigurationBuilder<T>
  - - org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder<T>
    - - org.apache.commons.configuration2.builder.ReloadingFileBasedConfigurationBuilder<T>

- Type Parameters:
    `T` - the concrete type of `Configuration` objects created by this builder
  All Implemented Interfaces:
    ConfigurationBuilder<T>, EventSource, ReloadingControllerSupport

      public class ReloadingFileBasedConfigurationBuilder<T extends FileBasedConfiguration>
      extends FileBasedConfigurationBuilder<T>
      implements ReloadingControllerSupport

  A specialized `ConfigurationBuilder` implementation which can handle configurations read from a `FileHandler` and supports reloading.

  This builder class exposes a `ReloadingController` object controlling reload operations on the file-based configuration produced as result object. For the `FileHandler` defining the location of the configuration a configurable `ReloadingDetector` is created and associated with the controller. So changes on the source file can be detected. When ever such a change occurs, the result object of this builder is reset. This means that the next time `getConfiguration()` is called a new `Configuration` object is created which is loaded from the modified file.

  Client code interested in notifications can register a listener at this builder to receive reset events. When such an event is received the new result object can be requested. This way client applications can be sure to work with an up-to-date configuration. It is also possible to register a listener directly at the `ReloadingController`.

  This builder does not actively trigger the `ReloadingController` to perform a reload check. This has to be done by an external component, e.g. a timer.

  Since:
    2.0
  Version:
    $Id: ReloadingFileBasedConfigurationBuilder.java 1678618 2015-05-10 20:15:01Z oheger $

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `ReloadingFileBasedConfigurationBuilder(Class<? extends T> resCls)` Creates a new instance of `ReloadingFileBasedConfigurationBuilder` which produces result objects of the specified class.
    `ReloadingFileBasedConfigurationBuilder(Class<? extends T> resCls, Map<String,Object> params)` Creates a new instance of `ReloadingFileBasedConfigurationBuilder` which produces result objects of the specified class and sets initialization parameters.
    `ReloadingFileBasedConfigurationBuilder(Class<? extends T> resCls, Map<String,Object> params, boolean allowFailOnInit)` Creates a new instance of `ReloadingFileBasedConfigurationBuilder` which produces result objects of the specified class and sets initialization parameters and the allowFailOnInit flag.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `FileBasedConfigurationBuilder<T>` | `configure(BuilderParameters... params)` Appends the content of the specified `BuilderParameters` objects to the current initialization parameters.
    `protected ReloadingDetector` | `createReloadingDetector(FileHandler handler, FileBasedBuilderParametersImpl fbparams)` Creates a `ReloadingDetector` which monitors the passed in `FileHandler`.
    `ReloadingController` | `getReloadingController()` Returns the `ReloadingController` associated with this builder.
    `protected void` | `initFileHandler(FileHandler handler)` Initializes the new current `FileHandler`.

    - ### Methods inherited from class org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder

      `getDefaultEncoding, getFileHandler, initResultInstance, isAutoSave, save, setAutoSave, setDefaultEncoding, setParameters`

    - ### Methods inherited from class org.apache.commons.configuration2.builder.BasicConfigurationBuilder

      `addEventListener, addParameters, connectToReloadingController, copyEventListeners, copyEventListeners, createResult, createResultDeclaration, createResultInstance, fetchBeanHelper, fireBuilderEvent, getConfiguration, getParameters, getResultClass, getResultDeclaration, installEventListener, isAllowFailOnInit, removeEventListener, reset, resetParameters, resetResult`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### ReloadingFileBasedConfigurationBuilder

          public ReloadingFileBasedConfigurationBuilder(Class<? extends T> resCls,
                                                        Map<String,Object> params)

      Creates a new instance of `ReloadingFileBasedConfigurationBuilder` which produces result objects of the specified class and sets initialization parameters.
      Parameters:
        `resCls` - the result class (must not be null
        `params` - a map with initialization parameters
      Throws:
        `IllegalArgumentException` - if the result class is null

    - #### ReloadingFileBasedConfigurationBuilder

          public ReloadingFileBasedConfigurationBuilder(Class<? extends T> resCls,
                                                        Map<String,Object> params,
                                                        boolean allowFailOnInit)

      Creates a new instance of `ReloadingFileBasedConfigurationBuilder` which produces result objects of the specified class and sets initialization parameters and the allowFailOnInit flag.
      Parameters:
        `resCls` - the result class (must not be null
        `params` - a map with initialization parameters
        `allowFailOnInit` - the allowFailOnInit flag
      Throws:
        `IllegalArgumentException` - if the result class is null

    - #### ReloadingFileBasedConfigurationBuilder

          public ReloadingFileBasedConfigurationBuilder(Class<? extends T> resCls)

      Creates a new instance of `ReloadingFileBasedConfigurationBuilder` which produces result objects of the specified class.
      Parameters:
        `resCls` - the result class (must not be null
      Throws:
        `IllegalArgumentException` - if the result class is null

  - ### Method Detail

    - #### getReloadingController

          public ReloadingController getReloadingController()

      Returns the `ReloadingController` associated with this builder. This controller is directly created. However, it becomes active (i.e. associated with a meaningful reloading detector) not before a result object was created.
      Specified by:
        `getReloadingController` in interface `ReloadingControllerSupport`
      Returns:
        the `ReloadingController`

    - #### configure

          public FileBasedConfigurationBuilder<T> configure(BuilderParameters... params)

      Appends the content of the specified `BuilderParameters` objects to the current initialization parameters. Calling this method multiple times will create a union of the parameters provided. This method is overridden here to change the result type. This method is overridden here to change the result type.
      Overrides:
        `configure` in class `FileBasedConfigurationBuilder<T extends FileBasedConfiguration>`
      Parameters:
        `params` - an arbitrary number of objects with builder parameters
      Returns:
        a reference to this builder for method chaining

    - #### createReloadingDetector

          protected ReloadingDetector createReloadingDetector(FileHandler handler,
                                                              FileBasedBuilderParametersImpl fbparams)
                                                       throws ConfigurationException

      Creates a `ReloadingDetector` which monitors the passed in `FileHandler`. This method is called each time a new result object is created with the current `FileHandler`. This implementation checks whether a `ReloadingDetectorFactory` is specified in the current parameters. If this is the case, it is invoked. Otherwise, a default factory is used to create a `FileHandlerReloadingDetector` object. Note: This method is called from a synchronized block.
      Parameters:
        `handler` - the current `FileHandler`
        `fbparams` - the object with parameters related to file-based builders
      Returns:
        a `ReloadingDetector` for this `FileHandler`
      Throws:
        `ConfigurationException` - if an error occurs

    - #### initFileHandler

          protected void initFileHandler(FileHandler handler)
                                  throws ConfigurationException

      Initializes the new current `FileHandler`. When a new result object is created, a new `FileHandler` is created, too, and associated with the result object. This new handler is passed to this method. If a location is defined, the result object is loaded from this location. Note: This method is called from a synchronized block. This implementation also takes care that a new `ReloadingDetector` for the new current `FileHandler` is created. Also, the reloading controller's reloading state has to be reset; after the creation of a new result object changes in the underlying configuration source have to be monitored again.
      Overrides:
        `initFileHandler` in class `FileBasedConfigurationBuilder<T extends FileBasedConfiguration>`
      Parameters:
        `handler` - the new current `FileHandler`
      Throws:
        `ConfigurationException` - if an error occurs

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