Package freemarker.template

Interface TransformControl

  • public interface TransformControl
    An interface that can be implemented by writers returned from TemplateTransformModel.getWriter(java.io.Writer, java.util.Map). The methods on this interfaces are callbacks that will be called by the template engine and that give the writer a chance to better control the evaluation of the transform body. The writer can instruct the engine to skip or to repeat body evaluation, and gets notified about exceptions that are thrown during the body evaluation.

    • Field Detail

      • REPEAT_EVALUATION

        static final int REPEAT_EVALUATION
        Constant returned from afterBody() that tells the template engine to repeat transform body evaluation and feed it again to the transform.
        See Also:
        Constant Field Values

      • END_EVALUATION

        static final int END_EVALUATION
        Constant returned from afterBody() that tells the template engine to end the transform and close the writer.
        See Also:
        Constant Field Values

      • SKIP_BODY

        static final int SKIP_BODY
        Constant returned from onStart() that tells the template engine to skip evaluation of the body.
        See Also:
        Constant Field Values

      • EVALUATE_BODY

        static final int EVALUATE_BODY
        Constant returned from onStart() that tells the template engine to evaluate the body.
        See Also:
        Constant Field Values

    • Method Detail

      • onStart

        int onStart()
     throws TemplateModelException,
            java.io.IOException
        Called before the body is evaluated for the first time.
        Returns:
        • SKIP_BODY if the transform wants to ignore the body. In this case, only Writer.close() is called next and processing ends.
        • EVALUATE_BODY to normally evaluate the body of the transform and feed it to the writer
        Throws:
        TemplateModelException
        java.io.IOException

      • afterBody

        int afterBody()
       throws TemplateModelException,
              java.io.IOException
        Called after the body has been evaluated.
        Returns:
        • END_EVALUATION if the transformation should be ended.
        • REPEAT_EVALUATION to have the engine re-evaluate the transform body and feed it again to the writer.
        Throws:
        TemplateModelException
        java.io.IOException

      • onError

        void onError​(java.lang.Throwable t)
      throws java.lang.Throwable
        Called if any exception occurs during the transform between the TemplateTransformModel.getWriter(java.io.Writer, java.util.Map) call and the Writer.close() call.
        Parameters:
        t - the throwable that represents the exception. It can be any non-checked throwable, as well as TemplateException and IOException.
        Throws:
        java.lang.Throwable - is recommended that the methods rethrow the received throwable. If the method wants to throw another throwable, it should either throw a non-checked throwable, or an instance of TemplateException and IOException. Throwing any other checked exception will cause the engine to rethrow it as a UndeclaredThrowableException.