org.apache.logging.log4j.message
Interface Message
- All Superinterfaces:
- Serializable
- All Known Subinterfaces:
- MultiformatMessage
- All Known Implementing Classes:
- LocalizedMessage, MapMessage, ObjectMessage, ParameterizedMessage, SimpleMessage, StringFormattedMessage, StructuredDataMessage, ThreadDumpMessage
public interface Message
- extends Serializable
An interface for various Message implementations that can be logged. Messages can act as wrappers
around Objects so that user can have control over converting Objects to Strings when necessary without
requiring complicated formatters and as a way to manipulate the message based on information available
at runtime such as the locale of the system.
Note: Message objects should not be considered to be thread safe nor should they be assumed to be
safely reusable even on the same thread. The logging system may provide information to the Message
objects and the Messages might be queued for asynchronous delivery. Thus, any modifications to a
Message object by an application should by avoided after the Message has been passed as a parameter on
a Logger method.
- Troublesome:
- Interfaces should rarely extend Serializable according to Effective Java 2nd Ed pg 291.
(RG) That section also says "If a class or interface exists primarily to participate in a framework that
requires all participants to implement Serializable, then it makes perfect sense for the class or
interface to implement or extend Serializable". Such is the case here as the LogEvent must be Serializable.
getFormattedMessage
String getFormattedMessage()
- Returns the Message formatted as a String. Each Message implementation determines the
appropriate way to format the data encapsulated in the Message. Messages that provide
more than one way of formatting the Message will implement MultiformatMessage.
- Returns:
- The message String.
getFormat
String getFormat()
- Returns the format portion of the Message.
- Returns:
- The message format. Some implementations, such as ParameterizedMessage, will use this as
the message "pattern". Other Messages may simply return an empty String.
- Troublesome:
- Do all messages have a format? What syntax? Using a Formatter object could be cleaner.
(RG) In SimpleMessage the format is identical to the formatted message. In ParameterizedMessage and
StructuredDataMessage it is not. It is up to the Message implementer to determine what this
method will return. A Formatter is inappropriate as this is very specific to the Message
implementation so it isn't clear to me how having a Formatter separate from the Message would be cleaner.
getParameters
Object[] getParameters()
- Returns parameter values, if any.
- Returns:
- An array of parameter values or null.
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