org.apache.turbine.services.velocity

## Class TurbineVelocityService

- java.lang.Object
- - org.apache.turbine.services.BaseInitable
  - - org.apache.turbine.services.BaseService
    - - org.apache.turbine.services.TurbineBaseService
      - - org.apache.turbine.services.template.BaseTemplateEngineService
        - - org.apache.turbine.services.velocity.TurbineVelocityService

- All Implemented Interfaces:
    Initable, Service, TemplateEngineService, VelocityService, org.apache.velocity.app.event.EventHandler, org.apache.velocity.app.event.MethodExceptionEventHandler

      public class TurbineVelocityService
      extends BaseTemplateEngineService
      implements VelocityService, org.apache.velocity.app.event.MethodExceptionEventHandler

  This is a Service that can process Velocity templates from within a Turbine Screen. It is used in conjunction with the templating service as a Templating Engine for templates ending in "vm". It registers itself as translation engine with the template service and gets accessed from there. After configuring it in your properties, it should never be necessary to call methods from this service directly. Here's an example of how you might use it from a screen:
  `Context context = TurbineVelocity.getContext(data);
  context.put("message", "Hello from Turbine!");
  String results = TurbineVelocity.handleRequest(context,"helloWorld.vm");
  data.getPage().getBody().addElement(results);
  `
  Version:
    $Id: TurbineVelocityService.java 1773378 2016-12-09 13:19:59Z tv $
  Author:
    Dave Bryson, Rafal Krzewski, Jason van Zyl, Sean Legassick, Daniel Rall, Henning P. Schmiedehausen, Eric Pugh, Peter Courcoux

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from interface org.apache.velocity.app.event.MethodExceptionEventHandler

      `org.apache.velocity.app.event.MethodExceptionEventHandler.MethodExceptionExecutor`

  - ### Field Summary

    - ### Fields inherited from class org.apache.turbine.services.BaseService

      `name, serviceBroker`

    - ### Fields inherited from class org.apache.turbine.services.BaseInitable

      `initableBroker, isInitialized`

    - ### Fields inherited from interface org.apache.turbine.services.velocity.VelocityService

      `CATCH_ERRORS_DEFAULT, CATCH_ERRORS_KEY, CONTEXT, PIPELINEDATA_KEY, RUNDATA_KEY, SERVICE_NAME, VELOCITY_EXTENSION`

    - ### Fields inherited from interface org.apache.turbine.services.template.TemplateEngineService

      `DEFAULT_ERROR_SCREEN, DEFAULT_LAYOUT, DEFAULT_LAYOUT_TEMPLATE, DEFAULT_NAVIGATION, DEFAULT_NAVIGATION_TEMPLATE, DEFAULT_PAGE, DEFAULT_SCREEN, DEFAULT_SCREEN_TEMPLATE, DEFAULT_TEMPLATE_EXTENSION, TEMPLATE_EXTENSIONS`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `TurbineVelocityService()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `org.apache.commons.collections.ExtendedProperties` | `createVelocityProperties(org.apache.commons.configuration.Configuration conf)` This method generates the Extended Properties object necessary for the initialization of Velocity.
    `org.apache.velocity.context.Context` | `getContext()` Create a Context object that also contains the globalContext.
    `org.apache.velocity.context.Context` | `getContext(PipelineData pipelineData)` Create a Context from the PipelineData object.
    `org.apache.velocity.context.Context` | `getNewContext()` This method returns a new, empty Context object.
    `String` | `handleRequest(org.apache.velocity.context.Context context, String filename)` Process the request and fill in the template with the values you set in the Context.
    `void` | `handleRequest(org.apache.velocity.context.Context context, String filename, OutputStream output)` Process the request and fill in the template with the values you set in the Context.
    `void` | `handleRequest(org.apache.velocity.context.Context context, String filename, Writer writer)` Process the request and fill in the template with the values you set in the Context.
    `void` | `init()` Load all configured components and initialize them.
    `Object` | `methodException(Class clazz, String method, Exception e)` MethodException Event Cartridge handler for Velocity.
    `void` | `requestFinished(org.apache.velocity.context.Context context)` Performs post-request actions (releases context tools back to the object pool).
    `boolean` | `templateExists(String template)` Find out if a given template exists.

    - ### Methods inherited from class org.apache.turbine.services.template.BaseTemplateEngineService

      `getAssociatedFileExtensions, getTemplateEngineServiceConfiguration, initConfiguration, registerConfiguration`

    - ### Methods inherited from class org.apache.turbine.services.TurbineBaseService

      `init, init, shutdown`

    - ### Methods inherited from class org.apache.turbine.services.BaseService

      `getConfiguration, getName, getProperties, getServiceBroker, setName, setServiceBroker`

    - ### Methods inherited from class org.apache.turbine.services.BaseInitable

      `getInit, getInitableBroker, setInit, setInitableBroker`

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

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

    - ### Methods inherited from interface org.apache.turbine.services.Service

      `getConfiguration, getName, getProperties, setName, setServiceBroker`

    - ### Methods inherited from interface org.apache.turbine.services.Initable

      `getInit, init, setInitableBroker, shutdown`

- - ### Constructor Detail

    - #### TurbineVelocityService

          public TurbineVelocityService()

  - ### Method Detail

    - #### init

          public void init()
                    throws InitializationException

      Load all configured components and initialize them. This is a zero parameter variant which queries the Turbine Servlet for its config.
      Specified by:
        `init` in interface `Initable`
      Overrides:
        `init` in class `TurbineBaseService`
      Throws:
        `InitializationException` - Something went wrong in the init stage

    - #### getContext

          public org.apache.velocity.context.Context getContext()

      Create a Context object that also contains the globalContext.
      Specified by:
        `getContext` in interface `VelocityService`
      Returns:
        A Context object.

    - #### getNewContext

          public org.apache.velocity.context.Context getNewContext()

      This method returns a new, empty Context object.
      Specified by:
        `getNewContext` in interface `VelocityService`
      Returns:
        A Context Object.

    - #### methodException

          public Object methodException(Class clazz,
                               String method,
                               Exception e)
                                 throws Exception

      MethodException Event Cartridge handler for Velocity. It logs an execption thrown by the velocity processing on error level into the log file
      Specified by:
        `methodException` in interface `org.apache.velocity.app.event.MethodExceptionEventHandler`
      Parameters:
        `clazz` - The class that threw the exception
        `method` - The Method name that threw the exception
        `e` - The exception that would've been thrown
      Returns:
        A valid value to be used as Return value
      Throws:
        `Exception` - We threw the exception further up

    - #### getContext

          public org.apache.velocity.context.Context getContext(PipelineData pipelineData)

      Create a Context from the PipelineData object. Adds a pointer to the PipelineData object to the VelocityContext so that PipelineData is available in the templates.
      Specified by:
        `getContext` in interface `VelocityService`
      Parameters:
        `pipelineData` - The Turbine PipelineData object.
      Returns:
        A clone of the WebContext needed by Velocity.

    - #### handleRequest

          public String handleRequest(org.apache.velocity.context.Context context,
                             String filename)
                               throws TurbineException

      Process the request and fill in the template with the values you set in the Context.
      Specified by:
        `handleRequest` in interface `VelocityService`
      Parameters:
        `context` - The populated context.
        `filename` - The file name of the template.
      Returns:
        The process template as a String.
      Throws:
        `TurbineException` - Any exception thrown while processing will be wrapped into a TurbineException and rethrown.

    - #### handleRequest

          public void handleRequest(org.apache.velocity.context.Context context,
                           String filename,
                           OutputStream output)
                             throws TurbineException

      Process the request and fill in the template with the values you set in the Context.
      Specified by:
        `handleRequest` in interface `VelocityService`
      Parameters:
        `context` - A Context.
        `filename` - A String with the filename of the template.
        `output` - A OutputStream where we will write the process template as a String.
      Throws:
        `TurbineException` - Any exception thrown while processing will be wrapped into a TurbineException and rethrown.

    - #### handleRequest

          public void handleRequest(org.apache.velocity.context.Context context,
                           String filename,
                           Writer writer)
                             throws TurbineException

      Process the request and fill in the template with the values you set in the Context.
      Specified by:
        `handleRequest` in interface `VelocityService`
      Parameters:
        `context` - A Context.
        `filename` - A String with the filename of the template.
        `writer` - A Writer where we will write the process template as a String.
      Throws:
        `TurbineException` - Any exception thrown while processing will be wrapped into a TurbineException and rethrown.

    - #### createVelocityProperties

          public org.apache.commons.collections.ExtendedProperties createVelocityProperties(org.apache.commons.configuration.Configuration conf)
                                                                                     throws Exception

      This method generates the Extended Properties object necessary for the initialization of Velocity. It also converts the various resource loader pathes into webapp relative pathes. It also
      Parameters:
        `conf` - The Velocity Service configuration
      Returns:
        An ExtendedProperties Object for Velocity
      Throws:
        `Exception` - If a problem occurred while converting the properties.

    - #### templateExists

          public boolean templateExists(String template)

      Find out if a given template exists. Velocity will do its own searching to determine whether a template exists or not.
      Specified by:
        `templateExists` in interface `TemplateEngineService`
      Specified by:
        `templateExists` in class `BaseTemplateEngineService`
      Parameters:
        `template` - String template to search for
      Returns:
        True if the template can be loaded by Velocity
      See Also:
        `TemplateEngineService.templateExists(java.lang.String)`

    - #### requestFinished

          public void requestFinished(org.apache.velocity.context.Context context)

      Performs post-request actions (releases context tools back to the object pool).
      Specified by:
        `requestFinished` in interface `VelocityService`
      Parameters:
        `context` - a Velocity Context

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