Please initialize the log4j system properly warnin

问题:

Here is the error message -

log4j:WARN No appenders could be found for logger (SerialPortUtil).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

Here is the invocation in the SerialPortUtil class -

private static final Logger log = Logger.getLogger(SerialPortUtil.class.getSimpleName());
.
.
.
log.info("Serial port " + port.getName() + " is available");

Here is the content of my log4j.properties file -

log4j.rootLogger=DebugAppender

#Debug logging
log4j.appender.DebugAppender=org.apache.log4j.RollingFileAppender
log4j.appender.DebugAppender.Threshold=DEBUG
log4j.appender.DebugAppender.File=activityLog.log
log4j.appender.DebugAppender.MaxFileSize=200KB
log4j.appender.DebugAppender.MaxBackupIndex=5
log4j.appender.DebugAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.DebugAppender.layout.ConversionPattern=%d{DATE} %t - %m%n

And the property file is on the classpath.

Everything looks right to me, so what's going on? Shouldn't the DEBUG threshold also capture INFO logging?

回答1:

From the link in the error message:

This occurs when the default configuration files log4j.properties and log4j.xml can not be found and the application performs no explicit configuration. log4j uses Thread.getContextClassLoader().getResource() to locate the default configuration files and does not directly check the file system. Knowing the appropriate location to place log4j.properties or log4j.xml requires understanding the search strategy of the class loader in use. log4j does not provide a default configuration since output to the console or to the file system may be prohibited in some environments. Also see FAQ: Why can't log4j find my properties in a J2EE or WAR application?.

The configuration file cannot be found. Are you using xml or a property file??

Also, use logback!

回答2:

Alright, so I got it working by changing this

log4j.rootLogger=DebugAppender

to this

log4j.rootLogger=DEBUG, DebugAppender

Apparently you have to specify the logging level to the rootLogger first? I apologize if I wasted anyone's time.

Also, I decided to answer my own question because this wasn't a classpath issue.

回答3:

The fix for me was to put "log4j.properties" into the "src" folder. It did not work in my package folder it has to be one up at the very root of source. Adding it to the build path which then moves it to the "Reference Libraries" also did not work.

To repeat: put log4j.properties at the root of your src folder.

my log4j.properties files has the following content which works on the latest version of Spring Tool Suite which is based on Eclipse.

# Configure logging for testing: optionally with log file
#log4j.rootLogger=INFO, stdout
log4j.rootLogger=WARN, stdout, logfile

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%

回答4:

If you are encountering the error/warning when you're running a program that uses log4j, the solution is to add a log4j.properties that can be seen by the class loader. Normally it's in the "src" folder of your Java project: Add the following contents to the file

log4j.rootLogger=INFO, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

回答5:

Try doing something like the following in main:

public static void main(String[] args) {
     PropertyConfigurator.configure(args[0]);
    //... your code

you need to tell log4j what its configuration should be.

回答6:

Add the code

BasicConfigurator.configure();

in your static main class as below..

Note: add " \hadoop-2.7.1\share\hadoop\common\lib\commons-logging-1.1.3.jar & \hadoop-2.7.1\share\hadoop\common\lib\log4j-1.2.17.jar " as the external references

import org.apache.log4j.BasicConfigurator;

public class ViewCountDriver extends Configured implements Tool{

    public static void main(String[]args) throws Exception{

        BasicConfigurator.configure(); 

        int exitcode = ToolRunner.run(new ViewCountDriver(), args);
        System.exit(exitcode); 
    }
}

回答7:

To add to @Gevorg, if you have a similar situation running Spark locally, place the log4j.properties file in the folder named resources under the main folder.

回答8:

This work for me:

public static void main(String[] args) {

        Properties props = new Properties();
        props.load(new FileInputStream("src/log4j.properties"));
        PropertyConfigurator.configure(props);

回答9:

What worked for me is to create a log4j properties file (you can find many examples over the net) and place it in properties folder in your project directory (create this folder if not exicts). The right click on the folder and Build Path->Use as Source Folder.

Hope it helps!

回答10:

just configure your log4j property file path in beginning of main method: e.g.: PropertyConfigurator.configure("D:\files\log4j.properties");