org.apache.turbine.modules.screens

## Class TemplateScreen

- java.lang.Object
- - org.apache.turbine.modules.Assembler
  - - org.apache.turbine.modules.Screen
    - - org.apache.turbine.modules.screens.TemplateScreen

- Direct Known Subclasses:
    BaseJspScreen, VelocityScreen

      public abstract class TemplateScreen
      extends Screen

  Template Screen. Base Template Screens should extend this class and override the buildTemplate() method. Users of the particular service can then override the doBuildTemplate() for any specific pre-processing. You can also override the doBuild() method in order to add extra functionality to your system, but you need to make sure to at least duplicate the existing functionality in order for things to work. Look at the code for the doBuild() method to get an idea of what is going on there (it is quite simple really).
  Version:
    $Id: TemplateScreen.java 1709648 2015-10-20 17:08:10Z tv $
  Author:
    Dave Bryson, Henning P. Schmiedehausen, Peter Courcoux

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected org.apache.commons.logging.Log` | `log` Logging

    - ### Fields inherited from class org.apache.turbine.modules.Screen

      `CACHE_SIZE_DEFAULT, CACHE_SIZE_KEY, NAME, PREFIX`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `TemplateScreen()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract String` | `buildTemplate(PipelineData pipelineData)` This method should be implemented by Base template classes.
    `protected String` | `doBuild(PipelineData pipelineData)` This method is called by the Screenloader to construct the Screen.
    `protected abstract void` | `doBuildTemplate(PipelineData pipelineData)` This method should be overridden by subclasses that wish to add specific business logic.
    `protected void` | `doPostBuildTemplate(PipelineData pipelineData)` This method can be overridden to write code that executes when the template has been built (called from a finally clause, so executes regardless of whether an exception is thrown or not)
    `void` | `doRedirect(PipelineData pipelineData, String template)` You can call this within a Screen to cause an internal redirect to happen.
    `void` | `doRedirect(PipelineData pipelineData, String screen, String template)` You can call this within a Screen to cause an internal redirect to happen.
    `static void` | `setTemplate(PipelineData pipelineData, String template)` This method is used when you want to short circuit a Screen and change the template that will be executed next.

    - ### Methods inherited from class org.apache.turbine.modules.Screen

      `build, getLayout, getPrefix, setLayout`

    - ### Methods inherited from class org.apache.turbine.modules.Assembler

      `getRunData`

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

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

- - ### Field Detail

    - #### log

          protected org.apache.commons.logging.Log log

      Logging

  - ### Constructor Detail

    - #### TemplateScreen

          public TemplateScreen()

  - ### Method Detail

    - #### doBuildTemplate

          protected abstract void doBuildTemplate(PipelineData pipelineData)
                                           throws Exception

      This method should be overridden by subclasses that wish to add specific business logic.
      Parameters:
        `pipelineData` - Turbine information.
      Throws:
        `Exception` - A generic exception.

    - #### buildTemplate

          public abstract String buildTemplate(PipelineData pipelineData)
                                        throws Exception

      This method should be implemented by Base template classes. It should contain the specific template service code to generate the template.
      Parameters:
        `pipelineData` - Turbine information.
      Returns:
        the content of the screen
      Throws:
        `Exception` - A generic exception.

    - #### doPostBuildTemplate

          protected void doPostBuildTemplate(PipelineData pipelineData)

      This method can be overridden to write code that executes when the template has been built (called from a finally clause, so executes regardless of whether an exception is thrown or not)

    - #### doBuild

          protected String doBuild(PipelineData pipelineData)
                            throws Exception

      This method is called by the Screenloader to construct the Screen.
      Specified by:
        `doBuild` in class `Screen`
      Parameters:
        `pipelineData` - Turbine information.
      Returns:
        the content of the screen
      Throws:
        `Exception` - A generic exception.

    - #### setTemplate

          public static void setTemplate(PipelineData pipelineData,
                         String template)

      This method is used when you want to short circuit a Screen and change the template that will be executed next. Note that the current context will be applied to the next template that is executed. If you want to have the context executed for the next screen, to be the same one as the next screen, then you should use the TemplateScreen.doRedirect() method.
      Parameters:
        `pipelineData` - Turbine information.
        `template` - The name of the next template.

    - #### doRedirect

          public void doRedirect(PipelineData pipelineData,
                        String screen,
                        String template)
                          throws Exception

      You can call this within a Screen to cause an internal redirect to happen. It essentially allows you to stop execution in one Screen and instantly execute another Screen. Don't worry, this does not do a HTTP redirect and also if you have anything added in the Context, it will get carried over.

      This class is useful if you have a Screen that submits to another Screen and you want it to do error validation before executing the other Screen. If there is an error, you can doRedirect() back to the original Screen.

      Parameters:
        `pipelineData` - Turbine information.
        `screen` - Name of screen to redirect to.
        `template` - Name of template.
      Throws:
        `Exception` - A generic exception.

    - #### doRedirect

          public void doRedirect(PipelineData pipelineData,
                        String template)
                          throws Exception

      You can call this within a Screen to cause an internal redirect to happen. It essentially allows you to stop execution in one Screen and instantly execute another Screen. Don't worry, this does not do a HTTP redirect and also if you have anything added in the Context, it will get carried over.

      This class is useful if you have a Screen that submits to another Screen and you want it to do error validation before executing the other Screen. If there is an error, you can doRedirect() back to the original Screen.

      Parameters:
        `pipelineData` - Turbine information.
        `template` - Name of template.
      Throws:
        `Exception` - A generic exception.

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