📖Logging

Class Features

• Uses the standard Java Logging framework java.util.logging (not Apache Log4j). It is part of Java SE and therefore, no additional library is needed.

• Capable of writing more than 10'000 lines/sec on a MacBook Pro using the FileHandler and KLogLineFormatter.

• Reduces logging complexity to debug, error and info messages

• All methods are static (no instantiation needed)

• Handler and formatter classes are provided to format data as tabular text, CSV, XML, JSON and YAML or to send data to any JDBC compliant database or all errors to any SMTP server

• Add precise timestamp and exact code location to the formatted log output

• To enable logging, the configuration file KLog.properties must be in the current directory

• The configured logging level may be changed during execution with setLevelxxx() and reset again to the configured value with resetLevel()

The Java Utility Package ch.k43.util is using the KLog functions internally to help you during problem determination. Just set the log level to FINEST to enable the debugging mode in the KLog.properties file. This will get you detailed information during the execution of your code.

KLog Properties File

The logging properties file enables and configures the logging framework used by all KLog methods. Simply download, edit and place the file in the current directory of your Java application.

4KB

KLog.properties

KLog Handlers

The following logging handlers classes are provided:

• KLogJDBCHandler: Send output to any JDBC compliant database

• KLogSMTPHandler: Send errors (FATAL log level) to any SMTP server

KLog Formatters

The log information (timestamp, logging level, code location and message) can be formatted with the following formatter classes:

• KLogCSVFormatter: Format data as a one-line CSV string

• KLogJSONFormatter: Format data as a multi-line JSON string

• KLogLineFormatter: Format data as a one-line tabular string

• KLogXMLFormatter: Format data as a multi-line XML string

• KLogYAMLFormatter: Format data as a multi-line YAML string

Examples

Code and Output

KLog.info("Program started");
		
int rc = -1;
KLog.error(rc != 0, "Return code is non-zero: " + rc);
	
KLog.debug("Just a debug message");
		
Exception e = new Exception("Program error");
KLog.error(e);
		
KLog.info("Program ended");

2024-08-29T15:49:27.867 D main[1]:ch.k43.util.KLog:open:462                            ===== Application started 2024-08-29T15:49:27.850 =====
2024-08-29T15:49:27.867 D main[1]:ch.k43.util.KLog:open:464                            Java Utility Package (Freeware) ch.k43.util Version 2024.08.29
2024-08-29T15:49:27.868 D main[1]:ch.k43.util.KLog:open:467                            Homepage java-util.k43.ch - Please send any feedback to [e-mail]
2024-08-29T15:49:27.889 D main[1]:ch.k43.util.KLog:open:469                            Host ab-macbook-pro (10.0.0.105)
2024-08-29T15:49:27.889 D main[1]:ch.k43.util.KLog:open:470                            OS platform Mac OS X (Version 14.6.1/aarch64)
2024-08-29T15:49:27.889 D main[1]:ch.k43.util.KLog:open:471                            Java version 17 (OpenJDK 64-Bit Server VM - Eclipse Adoptium)
2024-08-29T15:49:27.891 D main[1]:ch.k43.util.KLog:open:475                            Java heap maximum 16.00 GB, current 1.00 GB, used 4.80 MB, free 1019.20 MB
2024-08-29T15:49:27.891 D main[1]:ch.k43.util.KLog:open:479                            Java locale de/CH, local time UTC +02:00
2024-08-29T15:49:27.891 D main[1]:ch.k43.util.KLog:open:482                            Java classpath ../bin/:../lib/org.json.20230618.jar:../lib/jakarta-mail-1.6.7.jar
2024-08-29T15:49:27.891 I main[1]:Test:main:10                                         Program started
2024-08-29T15:49:27.892 E main[1]:Test:main:13                                         ===> Return code is non-zero: -1
2024-08-29T15:49:27.892 D main[1]:Test:main:15                                         Just a debug message
2024-08-29T15:49:27.892 E main[1]:Test:main:18                                         ===> java.lang.Exception: Program error
2024-08-29T15:49:27.892 E main[1]:Test:main:18                                         ===> Stack[1]: Test.main(Test.java:17)
2024-08-29T15:49:27.892 I main[1]:Test:main:20                                         Program ended

Log Exception

try {
   ...
} catch (Exception e) {
   KLog.error(e);
}

Log and Throw RuntimeException

try {
  ...
} catch (Exception e) {
  KLog.abort(e.toString());
}

Log and Throw IllegalArgumentException

public divide(double arg1, double arg2) {
  // Check arguments
  KLog.argException(arg2 == 0.0, "Divisor 0 not allowed");
  ...
}