Logger utility for Java that is very simple to configure and use.

The last compiled jar file is in dist directory.

Build with maven:

mvn clean install

Simple-logger is not available on Maven central repo.

Download it and install it into local maven repository:

wget https://matjazcerkvenik.si/download/simple-logger-1.7.2.jar
mvn install:install-file -Dfile=simple-logger-1.7.2.jar -DgroupId=si.matjazcerkvenik.simplelogger -DartifactId=simple-logger -Dversion=1.7.2 -Dpackaging=jar

Add maven dependency in pom.xml:

<dependency>
    <groupId>si.matjazcerkvenik.simplelogger</groupId>
    <artifactId>simple-logger</artifactId>
    <version>1.7.2</version>
</dependency>

In Java create new SimpleLogger object, set filename and start logging immediately:

SimpleLogger logger = new SimpleLogger("./test.log");
logger.info("Hello simple-logger!");

Simple-logger can be configured:

• directly in the code
• with properties file
• with environment variables

All parameters are optional and have default values.

Parameters:

filename - Relative or absolute path to log file.

level - Log level. Supported log levels: TRACE, DEBUG, INFO, WARN, ERROR, FATAL

append - Set true to append text to file, or false to delete file first.

verbose - Also send text to standard output (console).

maxFileSize - Maximum size of log file in megabytes.

maxBackupFiles - Number of rolling files. Active log file has suffix .log while older log files get suffix .log.1. When new log file is created, the index of old log files are shifted and the last file is deleted.

filePermissions - Set POSIX file permissions on log file

dateFormat - Date format in Java compatible syntax, for example:

• yyyy.MM.dd hh:mm:ss:SSS
• EEE, MMM d, yy
• h:mm a
• yyyy-MM-dd'T'HH:mm:ss.SSS Z

Create new object and set parameters.

SimpleLogger logger = new SimpleLogger();
logger.setFilename("./test.log")
logger.setAppend(true);
logger.setLogLevel(LEVEL.INFO)
logger.setDateFormat("yyyy.MM.dd hh:mm:ss:SSS");
logger.setVerbose(true);
logger.setMaxSizeMb(10);
logger.setBackup(5);

logger.info("Hello simple-logger!");

Prepare a simplelogger.properties file with parameters:

simplelogger.filename=./simple-logger.log
simplelogger.level=INFO
simplelogger.append=true
simplelogger.verbose=true
simplelogger.maxFileSize=1
simplelogger.maxBackupFiles=2
simplelogger.filepermissions=rw-r--r--
simplelogger.dateFormat=yyyy.MM.dd hh:mm:ss:SSS

Pass the properties to SimpleLogger when creating new object and start logging:

Properties props = new Properties();
props.load(new FileInputStream("./simplelogger.properties"));

SimpleLogger logger = new SimpleLogger(props);
logger.info("Hello simple-logger!");

Set environment variables:

SIMPLELOGGER_FILENAME="./simple-logger.log"
SIMPLELOGGER_LEVEL="INFO"
SIMPLELOGGER_APPEND="true"
SIMPLELOGGER_VERBOSE="true"
SIMPLELOGGER_MAXFILESIZE="1"
SIMPLELOGGER_MAXBACKUPFILES="2"
SIMPLELOGGER_FILEPERMISSIONS="rw-r--r--"
SIMPLELOGGER_DATEFORMAT="yyyy.MM.dd hh:mm:ss:SSS"

Use empty constructor when creating new SimpleLogger object.

Environment variables are always loaded first (if they exist, otherwise default values will apply). They can be overwritten by properties file or inline whenever is necessary.

SimpleLogger logger = new SimpleLogger();
logger.info("Hello simple-logger!");

Simple-logger can also be used to write some text quickly in the file. Those days when you are thinking about InputStreams and Readers and Buffers and are gone.

Call write method to write just plain text, whatever you like:

logger.write("Just some text");

Simple-logger can also log exception stacks:

try {...}
catch (Exception e) {
    logger.error("Exception is thrown: ", e);
}

It is recommended to close the simple-logger output streams before stopping application:

logger.close();

1.7.2

• set posix permissions on log file

1.7.1

• a fix in write function when writing log without timestamp

1.7.0

• Refactored and a bit redesigned, but mostly refactored
• Support configuration with environment variables

1.6.4

• Added write(text) method where the text is written to log file without checking log level. Date and log level is also not printed. Just text.

1.6.3

• SimpleLogger implements Serializable

1.6.2

• create directories on path if they don't exist

1.6.1

• close file writer

...