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.

Author:

Attila Szegedi

Field Summary

Fields

Modifier and Type	Field and Description
static int	END_EVALUATION Constant returned from afterBody() that tells the template engine to end the transform and close the writer.
static int	EVALUATE_BODY Constant returned from onStart() that tells the template engine to evaluate the body.
static int	REPEAT_EVALUATION Constant returned from afterBody() that tells the template engine to repeat transform body evaluation and feed it again to the transform.
static int	SKIP_BODY Constant returned from onStart() that tells the template engine to skip evaluation of the body.

Method Summary

Methods

Modifier and Type	Method and Description
int	afterBody() Called after the body has been evaluated.
void	onError(java.lang.Throwable t) Called if any exception occurs during the transform between the TemplateTransformModel.getWriter(java.io.Writer, java.util.Map) call and the Writer.close() call.
int	onStart() Called before the body is evaluated for the first time.

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.