Package org.nanonative.nano.helper.logger.logic

Class LogFormatterJson

java.lang.Object
java.util.logging.Formatter
org.nanonative.nano.helper.logger.logic.LogFormatterJson
public class LogFormatterJson extends Formatter
A log formatter that outputs log records in JSON format.

This formatter structures log messages into JSON objects, which is beneficial for systems that ingest log data for analysis, allowing for easy parsing and structured querying of log data.

Usage Example: 

 logger.info(() -> throwable, "Processed records - success: [{}], failure: [%s], ignored; [{2}]", successCount, failureCount, ignoreCount, Map.of("username", "yuna"));
In this example, 'successCount' replaces the first '{}' placeholder, 'failureCount' replaces the '%s' placeholder and 'ignoreCount' replaces the last [{2}] placeholder. The formatter will convert the log into a JSON line. The map's keys and values becoming part of the JSON structure. A key value map is not really needed as the keys and values from the messages itself becomes a part of the JSON structure as well. This makes it easier to switch between console and json logging.

Additionally, it supports automatic key-value extraction from the log message itself, enabling inline parameterization. The extracted keys and values are also included in the JSON output.

The formatter handles exceptions by appending a "error" field with the exception message to the JSON log entry.

  • Field Details

    • dateFormat

      protected final SimpleDateFormat dateFormat

    • MESSAGE_KEY_VALUE_PATTERN

      protected static final Pattern MESSAGE_KEY_VALUE_PATTERN

  • Constructor Details

    • LogFormatterJson

      public LogFormatterJson()

  • Method Details

    • format

      public String format(LogRecord logRecord)
      Formats a log record into a JSON string.
      Specified by:
      format in class Formatter
      Parameters:
      logRecord - The log record to format.
      Returns:
      The log record formatted as a JSON string.

    • extractKeyValuesFromMessage

      protected void extractKeyValuesFromMessage(Map<String,String> jsonMap, String message, Object[] params)
      Extracts key-value pairs from the message and stores them in a map.
      Parameters:
      jsonMap - The map to store the key-value pairs.
      message - The log message.
      params - The parameters for the log message.

    • addJsonEntries

      protected void addJsonEntries(Map<String,String> jsonMap, Object[] params)
      Adds additional key-value pairs to the map.
      Parameters:
      jsonMap - The map to store the key-value pairs.
      params - The parameters for the log message.

    • putEntry

      protected void putEntry(Map<String,String> jsonMap, Object key, Object value)
      Adds escaped and converted key-value pairs to the map.
      Parameters:
      jsonMap - The map to store the key-value pairs.
      key - key
      value - value

    • jsonEscape

      protected String jsonEscape(Object value)
      Escapes special characters for JSON compatibility.
      Parameters:
      value - The object to escape.
      Returns:
      The escaped string.