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

Class ExceptionResolver

java.lang.Object
org.apache.logging.log4j.layout.template.json.resolver.ExceptionResolver
All Implemented Interfaces:
EventResolver, TemplateResolver<LogEvent>
Direct Known Subclasses:
ExceptionRootCauseResolver
public class ExceptionResolver extends Object implements EventResolver
Exception resolver.

Note that this resolver is toggled by stackTraceEnabled layout configuration, which is by default populated from log4j.layout.jsonTemplate.stackTraceEnabled system property.

Configuration

 config              = field , [ stringified ] , [ stackTrace ]
 field               = "field" -> ( "className" | "message" | "stackTrace" )

 stackTrace          = "stackTrace" -> (
                         [ stringified ]
                       , [ elementTemplate ]
                       )

 stringified         = "stringified" -> ( boolean | truncation )
 truncation          = "truncation" -> (
                         [ suffix ]
                       , [ pointMatcherStrings ]
                       , [ pointMatcherRegexes ]
                       )
 suffix              = "suffix" -> string
 pointMatcherStrings = "pointMatcherStrings" -> string[]
 pointMatcherRegexes = "pointMatcherRegexes" -> string[]

 elementTemplate     = "elementTemplate" -> object
stringified is set to false by default. stringified at the root level is deprecated in favor of stackTrace.stringified, which has precedence if both are provided.

pointMatcherStrings and pointMatcherRegexes enable the truncation of stringified stack traces after the given matching point. If both parameters are provided, pointMatcherStrings will be checked first.

If a stringified stack trace truncation takes place, it will be indicated with a suffix, which by default is set to the configured truncatedStringSuffix in the layout, unless explicitly provided. Every truncation suffix is prefixed with a newline.

Stringified stack trace truncation operates in Caused by: and Suppressed: label blocks. That is, matchers are executed against each label in isolation.

elementTemplate is an object describing the template to be used while resolving the StackTraceElement array. If stringified is set to true, elementTemplate will be discarded. By default, elementTemplate is set to null and rather populated from the layout configuration. That is, the stack trace element template can also be provided using stackTraceElementTemplate and setStackTraceElementTemplateUri layout configuration parameters. The template to be employed is determined in the following order:

  1. elementTemplate provided in the resolver configuration
  2. stackTraceElementTemplate parameter from layout configuration (the default is populated from log4j.layout.jsonTemplate.stackTraceElementTemplate system property)
  3. stackTraceElementTemplateUri parameter from layout configuration (the default is populated from log4j.layout.jsonTemplate.stackTraceElementTemplateUri system property)

See StackTraceElementResolver for the list of available resolvers in a stack trace element template.

Examples

Resolve logEvent.getThrown().getClass().getCanonicalName(): 
  {
   "$resolver": "exception",
   "field": "className"
 }
Resolve the stack trace into a list of StackTraceElement objects: 
  {
   "$resolver": "exception",
   "field": "stackTrace"
 }
Resolve the stack trace into a string field: 
  {
   "$resolver": "exception",
   "field": "stackTrace",
   "stackTrace": {
     "stringified": true
   }
 }
Resolve the stack trace into a string field such that the content will be truncated after the given point matcher: 
  {
   "$resolver": "exception",
   "field": "stackTrace",
   "stackTrace": {
     "stringified": {
       "truncation": {
         "suffix": "... [truncated]",
         "pointMatcherStrings": ["at javax.servlet.http.HttpServlet.service"]
       }
     }
   }
 }
Resolve the stack trace into an object described by the provided stack trace element template: 
  {
   "$resolver": "exception",
   "field": "stackTrace",
   "stackTrace": {
     "elementTemplate": {
       "class": {
         "$resolver": "stackTraceElement",
         "field": "className"
       },
       "method": {
         "$resolver": "stackTraceElement",
         "field": "methodName"
       },
       "file": {
         "$resolver": "stackTraceElement",
         "field": "fileName"
       },
       "line": {
         "$resolver": "stackTraceElement",
         "field": "lineNumber"
       }
     }
   }
 }
See Also:

  • Method Details

    • isResolvable

      public boolean isResolvable()
      Description copied from interface: TemplateResolver
      Indicates if the resolver if applicable at all.

      For instance, the source line resolver can be short-circuited using this check if the location information is disabled in the layout configuration.

      Specified by:
      isResolvable in interface TemplateResolver<LogEvent>

    • isResolvable

      public boolean isResolvable(LogEvent logEvent)
      Description copied from interface: TemplateResolver
      Indicates if the resolver if applicable for the given value.

      For instance, the stack trace resolver can be short-circuited using this check if the stack traces are disabled in the layout configuration.

      Specified by:
      isResolvable in interface TemplateResolver<LogEvent>

    • 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>