org.apache.velocity.example

Class EventExample

java.lang.Object

org.slf4j.helpers.MarkerIgnoringBase

org.apache.velocity.example.EventExample

All Implemented Interfaces:

Serializable, EventHandler, InvalidReferenceEventHandler, MethodExceptionEventHandler, ReferenceInsertionEventHandler, org.slf4j.Logger

public class EventExample
extends org.slf4j.helpers.MarkerIgnoringBase
implements ReferenceInsertionEventHandler, MethodExceptionEventHandler, InvalidReferenceEventHandler

This class is a simple demonstration of how the event handling features of the Velocity Servlet Engine are used. It uses a custom logger as well to check the log message stream when testing the InvalidReferenceEventHandler.

Version:

$Id: EventExample.java 1871468 2019-12-14 12:20:11Z cbrisson $

Author:

Geir Magnusson Jr.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	LOG_LEVEL_DEBUG
static int	LOG_LEVEL_ERROR
static int	LOG_LEVEL_INFO
static int	LOG_LEVEL_TRACE
static int	LOG_LEVEL_WARN
protected String	name

Fields inherited from interface org.slf4j.Logger

ROOT_LOGGER_NAME

Constructor Summary

Constructors

Constructor and Description
EventExample()

Method Summary

Modifier and Type	Method and Description
void	debug(String msg)
void	debug(String format, Object... argArray)
void	debug(String format, Object param1)
void	debug(String format, Object param1, Object param2)
void	debug(String msg, Throwable t)
void	error(String msg)
void	error(String format, Object... argArray)
void	error(String format, Object arg)
void	error(String format, Object arg1, Object arg2)
void	error(String msg, Throwable t)
void	formatAndLog(int level, String format, Object... arguments) This prints the level and formatted message to System.out.
String	getName() Required init methods for Logger interface
void	info(String msg)
void	info(String format, Object... argArray)
void	info(String format, Object arg)
void	info(String format, Object arg1, Object arg2)
void	info(String msg, Throwable t)
Object	invalidGetMethod(Context context, String reference, Object object, String property, Info info) Called when object is null or there is no getter for the given property.
Object	invalidMethod(Context context, String reference, Object object, String method, Info info) Called when object is null or the given method does not exist.
boolean	invalidSetMethod(Context context, String leftreference, String rightreference, Info info) Event handler for when the right hand side of a #set() directive is null, which results in a log message.
boolean	isDebugEnabled()
boolean	isErrorEnabled()
boolean	isInfoEnabled()
boolean	isLevelEnabled(int level) This always returns true because logging levels can't be disabled in this impl.
boolean	isTraceEnabled()
boolean	isWarnEnabled()
void	log(int level, String message) This just prints the message and level to System.out.
void	log(int level, String message, Throwable t) This prints the level, message, and the Throwable's message to System.out.
static void	main(String[] args)
Object	methodException(Context context, Class claz, String method, Exception e, Info info) Called when a method throws an exception.
protected Object	readResolve()
Object	referenceInsert(Context context, String reference, Object value) Event handler for when a reference is inserted into the output stream.
void	throwException() silly method to throw an exception to demonstrate the method invocation exception event handling
void	trace(String msg)
void	trace(String format, Object... argArray)
void	trace(String format, Object param1)
void	trace(String format, Object param1, Object param2)
void	trace(String msg, Throwable t)
void	warn(String msg)
void	warn(String format, Object... argArray)
void	warn(String format, Object arg)
void	warn(String format, Object arg1, Object arg2)
void	warn(String msg, Throwable t)

Methods inherited from class org.slf4j.helpers.MarkerIgnoringBase

debug, debug, debug, debug, debug, error, error, error, error, error, info, info, info, info, info, isDebugEnabled, isErrorEnabled, isInfoEnabled, isTraceEnabled, isWarnEnabled, toString, trace, trace, trace, trace, trace, warn, warn, warn, warn, warn

Methods inherited from class java.lang.Object

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

Field Detail

LOG_LEVEL_TRACE

public static final int LOG_LEVEL_TRACE

See Also:

Constant Field Values

LOG_LEVEL_DEBUG

public static final int LOG_LEVEL_DEBUG

See Also:

Constant Field Values

LOG_LEVEL_INFO

public static final int LOG_LEVEL_INFO

See Also:

Constant Field Values

LOG_LEVEL_WARN

public static final int LOG_LEVEL_WARN

See Also:

Constant Field Values

LOG_LEVEL_ERROR

public static final int LOG_LEVEL_ERROR

See Also:

Constant Field Values

name

protected String name

Constructor Detail

EventExample

public EventExample()

Method Detail

main

public static void main(String[] args)

throwException

public void throwException()
                    throws Exception

silly method to throw an exception to demonstrate the method invocation exception event handling

Throws:

Exception

referenceInsert

public Object referenceInsert(Context context,
                              String reference,
                              Object value)

Event handler for when a reference is inserted into the output stream.

Specified by:

referenceInsert in interface ReferenceInsertionEventHandler

Parameters:

context - current context

reference - Reference from template about to be inserted.

value - Value about to be inserted (after its toString() method is called).

Returns:

Object on which toString() should be called for output.

invalidGetMethod

public Object invalidGetMethod(Context context,
                               String reference,
                               Object object,
                               String property,
                               Info info)

Description copied from interface: InvalidReferenceEventHandler

Called when object is null or there is no getter for the given property. Also called for invalid references without properties. invalidGetMethod() will be called in sequence for each link in the chain until the first non-null value is returned.

Specified by:

invalidGetMethod in interface InvalidReferenceEventHandler

Parameters:

context - the context when the reference was found invalid

reference - string with complete invalid reference

object - the object referred to, or null if not found

property - the property name from the reference

info - contains template, line, column details

Returns:

substitute return value for missing reference, or null if no substitute

invalidMethod

public Object invalidMethod(Context context,
                            String reference,
                            Object object,
                            String method,
                            Info info)

Description copied from interface: InvalidReferenceEventHandler

Called when object is null or the given method does not exist. invalidMethod() will be called in sequence for each link in the chain until the first non-null value is returned.

Specified by:

invalidMethod in interface InvalidReferenceEventHandler

Parameters:

context - the context when the reference was found invalid

reference - string with complete invalid reference

object - the object referred to, or null if not found

method - the name of the (non-existent) method

info - contains template, line, column details

Returns:

substitute return value for missing reference, or null if no substitute

invalidSetMethod

public boolean invalidSetMethod(Context context,
                                String leftreference,
                                String rightreference,
                                Info info)

Event handler for when the right hand side of a #set() directive is null, which results in a log message. This method gives the application a chance to 'vote' on msg generation

Specified by:

invalidSetMethod in interface InvalidReferenceEventHandler

Parameters:

context - the context when the reference was found invalid

leftreference - left reference being assigned to

rightreference - invalid reference on the right

info - contains info on template, line, col

Returns:

if true then stop calling invalidSetMethod along the chain.

methodException

public Object methodException(Context context,
                              Class claz,
                              String method,
                              Exception e,
                              Info info)

Description copied from interface: MethodExceptionEventHandler

Called when a method throws an exception. Only the first registered MethodExceptionEventHandler is called. If none are registered a MethodInvocationException is thrown.

Specified by:

methodException in interface MethodExceptionEventHandler

Parameters:

context - current context

claz - the class of the object the method is being applied to

method - the method

e - the thrown exception

info - contains template, line, column details

Returns:

an object to insert in the page

log

public void log(int level,
                String message)

This just prints the message and level to System.out.

log

public void log(int level,
                String message,
                Throwable t)

This prints the level, message, and the Throwable's message to System.out.

formatAndLog

public void formatAndLog(int level,
                         String format,
                         Object... arguments)

This prints the level and formatted message to System.out.

isLevelEnabled

public boolean isLevelEnabled(int level)

This always returns true because logging levels can't be disabled in this impl.

getName

public String getName()

Required init methods for Logger interface

Specified by:

getName in interface org.slf4j.Logger

Overrides:

getName in class org.slf4j.helpers.MarkerIgnoringBase

isTraceEnabled

public boolean isTraceEnabled()

Specified by:

isTraceEnabled in interface org.slf4j.Logger

trace

public void trace(String msg)

Specified by:

trace in interface org.slf4j.Logger

trace

public void trace(String format,
                  Object param1)

Specified by:

trace in interface org.slf4j.Logger

trace

public void trace(String format,
                  Object param1,
                  Object param2)

Specified by:

trace in interface org.slf4j.Logger

trace

public void trace(String format,
                  Object... argArray)

Specified by:

trace in interface org.slf4j.Logger

trace

public void trace(String msg,
                  Throwable t)

Specified by:

trace in interface org.slf4j.Logger

isDebugEnabled

public boolean isDebugEnabled()

Specified by:

isDebugEnabled in interface org.slf4j.Logger

debug

public void debug(String msg)

Specified by:

debug in interface org.slf4j.Logger

debug

public void debug(String format,
                  Object param1)

Specified by:

debug in interface org.slf4j.Logger

debug

public void debug(String format,
                  Object param1,
                  Object param2)

Specified by:

debug in interface org.slf4j.Logger

debug

public void debug(String format,
                  Object... argArray)

Specified by:

debug in interface org.slf4j.Logger

debug

public void debug(String msg,
                  Throwable t)

Specified by:

debug in interface org.slf4j.Logger

isInfoEnabled

public boolean isInfoEnabled()

Specified by:

isInfoEnabled in interface org.slf4j.Logger

info

public void info(String msg)

Specified by:

info in interface org.slf4j.Logger

info

public void info(String format,
                 Object arg)

Specified by:

info in interface org.slf4j.Logger

info

public void info(String format,
                 Object arg1,
                 Object arg2)

Specified by:

info in interface org.slf4j.Logger

info

public void info(String format,
                 Object... argArray)

Specified by:

info in interface org.slf4j.Logger

info

public void info(String msg,
                 Throwable t)

Specified by:

info in interface org.slf4j.Logger

isWarnEnabled

public boolean isWarnEnabled()

Specified by:

isWarnEnabled in interface org.slf4j.Logger

warn

public void warn(String msg)

Specified by:

warn in interface org.slf4j.Logger

warn

public void warn(String format,
                 Object arg)

Specified by:

warn in interface org.slf4j.Logger

warn

public void warn(String format,
                 Object arg1,
                 Object arg2)

Specified by:

warn in interface org.slf4j.Logger

warn

public void warn(String format,
                 Object... argArray)

Specified by:

warn in interface org.slf4j.Logger

warn

public void warn(String msg,
                 Throwable t)

Specified by:

warn in interface org.slf4j.Logger

isErrorEnabled

public boolean isErrorEnabled()

Specified by:

isErrorEnabled in interface org.slf4j.Logger

error

public void error(String msg)

Specified by:

error in interface org.slf4j.Logger

error

public void error(String format,
                  Object arg)

Specified by:

error in interface org.slf4j.Logger

error

public void error(String format,
                  Object arg1,
                  Object arg2)

Specified by:

error in interface org.slf4j.Logger

error

public void error(String format,
                  Object... argArray)

Specified by:

error in interface org.slf4j.Logger

error

public void error(String msg,
                  Throwable t)

Specified by:

error in interface org.slf4j.Logger

readResolve

protected Object readResolve()
                      throws ObjectStreamException

Throws:

ObjectStreamException