read .properties file using slf4j

Question

I want to read data from .properties file using slf4j,T i am able to output the data on console but what i want is to output the data on some file so i need file Appender for this which is declared in .properties file and i am not able to read the .properties file using slf4j.Can anyone help.

PS:I need an example that explains how to use.properties file in slf4j and how to initialize logger factory for that.

Answer 1

If using log4j, alternatively it can be used "Log4jLoggerAdapter", defining the configuration on a .properties file. Code below.

The required jars:

slf4j-api-1.7.5.jar
slf4j-log4j12-1.7.5.jar

If desired the source code (useful when debugging):
slf4j-api-1.7.5-sources.jar
slf4j-log4j12-1.7.5-sources.jar

The testing java class:

import org.apache.log4j.PropertyConfigurator; 
import org.slf4j.LoggerFactory;
import org.slf4j.impl.Log4jLoggerAdapter;


public class Slf4j_log4j_main {

    private static Log4jLoggerAdapter log = (Log4jLoggerAdapter) LoggerFactory.getLogger(Slf4j_log4j_main.class);

    public static void main(String[] args) {
        PropertyConfigurator.configure(Slf4j_log4j_main.class.getClassLoader().getResource("basic/log4j.properties"));
        log.debug( "a debug" );
        log.info( "an info" );
        log.warn("a warn");
        log.error("an error");
        //log.fatal("a fatal");  // slf4j misses fatal log.
        log.trace("a fatal");
        System.out.println("");
        System.out.println("[INFO]: done");
    }
}

The basic/log4j.properties

#@FROM: log4j_slf4j.basic
#@BASED: [BIN319P17]/[BIN319P42]
#using your own named logger.

# defining appender file
log=/home/alsdias/work/dev/java/lab/slf4j/log4j/log4j_slf4j/src/basic

# root logger setup
log4j.rootLogger = DEBUG, A1, FILE

#setting your own named logger. If more loggers, set additivity false (below)
log4j.logger.log4j.level=INFO,A1
log4j.additivity.log4j.level=false

# console appender config
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout

# Print the date in ISO 8601 format
log4j.appender.A1.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

# file appender config
log4j.appender.FILE=org.apache.log4j.FileAppender
log4j.appender.FILE.File=${log}/log.out

#setting the immediate flush to true (default)
log4j.appender.FILE.ImmediateFlush=true
#setting the threshold
log4j.appender.FILE.Threshold=debug
#setting the append to false, overwrite
log4j.appender.FILE.Append=false

#set a layout for the appender
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.conversionPattern=%d [%t] %-5p %c - %m%n

The generated output:

2013-06-14 11:47:00,473 [main] DEBUG basic.Slf4j_log4j_main - a debug
2013-06-14 11:47:00,474 [main] INFO  basic.Slf4j_log4j_main - an info
2013-06-14 11:47:00,474 [main] WARN  basic.Slf4j_log4j_main - a warn
2013-06-14 11:47:00,475 [main] ERROR basic.Slf4j_log4j_main - an error

[INFO]: done

Answer 2

slf4j is an API - if you consider it to consist only of interfaces and no classes, you are not far off.

The behavior you need is in the implementation of the interfaces, which for slf4j may be logback, AVSL, JDK14 (java.util.logging), log4j or Simple. Some can read properties, some cannot.

For logback you can use

<property file="src/main/java/chapters/configuration/variables1.properties" />

See http://logback.qos.ch/manual/configuration.html#definingProps for details.

Answer 3

See http://slf4j.org/faq.html.

SLF4J is only a facade, meaning that it does not provide a complete logging solution. Operations such as configuring appenders or setting logging levels cannot be performed with SLF4J.

slf4j-simple doesn't provide extra configuration features at all.

For other implementations you should use the way to configure they provide.

For example, log4j.properties for slf4j-log4j. See http://logging.apache.org/log4j/1.2/manual.html#Configuration.