Package org.apache.logging.log4j.layout.template.json.resolver

Class MessageResolver

java.lang.Object

org.apache.logging.log4j.layout.template.json.resolver.MessageResolver

All Implemented Interfaces:

EventResolver, TemplateResolver<LogEvent>

public final class MessageResolver
extends java.lang.Object
implements EventResolver

Message resolver.

Configuration

 config      = [ stringified ] , [ fallbackKey ]
 stringified = "stringified" -> boolean
 fallbackKey = "fallbackKey" -> string
 

Examples

Resolve the message into a string:

 {
   "$resolver": "message",
   "stringified": true
 }
 

Resolve the message such that if it is a ObjectMessage or MultiformatMessage with JSON support, its emitted JSON type (string, list, object, etc.) will be retained:

 {
   "$resolver": "message"
 }
 

Given the above configuration, a SimpleMessage will generate a "sample log message", whereas a MapMessage will generate a {"action": "login", "sessionId": "87asd97a"}. Certain indexed log storage systems (e.g., Elasticsearch) will not allow both values to coexist due to type mismatch: one is a string while the other is an object. Here one can use a fallbackKey to work around the problem:

 {
   "$resolver": "message",
   "fallbackKey": "formattedMessage"
 }
 

Using this configuration, a SimpleMessage will generate a {"formattedMessage": "sample log message"} and a MapMessage will generate a {"action": "login", "sessionId": "87asd97a"}. Note that both emitted JSONs are of type object and have no type-conflicting fields.

Field Summary

Fields

Modifier and Type	Field	Description
private static java.lang.String[]	FORMATS
private EventResolver	internalResolver

Constructor Summary

Constructors

Constructor	Description
MessageResolver(TemplateResolverConfig config)

Method Summary

Modifier and Type	Method	Description
private static EventResolver	createInternalResolver(TemplateResolverConfig config)
private static EventResolver	createObjectResolver(java.lang.String fallbackKey)
private static EventResolver	createStringResolver(java.lang.String fallbackKey)
(package private) static java.lang.String	getName()
void	resolve(LogEvent logEvent, JsonWriter jsonWriter)	Resolves the given value using the provided JsonWriter.
private static void	resolveString(java.lang.String fallbackKey, LogEvent logEvent, JsonWriter jsonWriter)
private static void	resolveString(java.lang.String fallbackKey, Message message, JsonWriter jsonWriter)
private static boolean	writeMultiformatMessage(JsonWriter jsonWriter, Message message)
private static boolean	writeObjectMessage(JsonWriter jsonWriter, Message message)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.logging.log4j.layout.template.json.resolver.TemplateResolver

isFlattening, isResolvable, isResolvable, resolve

Field Detail

FORMATS

private static final java.lang.String[] FORMATS

internalResolver

private final EventResolver internalResolver

Constructor Detail

MessageResolver

MessageResolver(TemplateResolverConfig config)

Method Detail

getName

static java.lang.String getName()

createInternalResolver

private static EventResolver createInternalResolver(TemplateResolverConfig config)

resolve

public void resolve(LogEvent logEvent,
                    JsonWriter jsonWriter)

Description copied from interface: TemplateResolver

Resolves the given value using the provided JsonWriter.

Specified by:

resolve in interface TemplateResolver<LogEvent>

createStringResolver

private static EventResolver createStringResolver(java.lang.String fallbackKey)

resolveString

private static void resolveString(java.lang.String fallbackKey,
                                  LogEvent logEvent,
                                  JsonWriter jsonWriter)

resolveString

private static void resolveString(java.lang.String fallbackKey,
                                  Message message,
                                  JsonWriter jsonWriter)

createObjectResolver

private static EventResolver createObjectResolver(java.lang.String fallbackKey)

writeMultiformatMessage

private static boolean writeMultiformatMessage(JsonWriter jsonWriter,
                                               Message message)

writeObjectMessage

private static boolean writeObjectMessage(JsonWriter jsonWriter,
                                          Message message)