Show detailed error in Logger when running Java on server

Symptoms

When "Run on server [^ 1]", when using Logger to output to the console, the" Configuration "level and below were not displayed.

Conclusion

--Set the output destination to a file. I gave up printing to the console. --Set not only setLevel (Level.ALL) of FileHandler but alsosetLevel (Level.ALL) of Logger.

environment

Eclipse 2019-03 (4.11.0) Tomcat 9 Java 11 macOS 10.13.6

comment

It seems that there are some configuration files to output to the console. Article [1] I was able to solve it, but since I used it by overriding Formatter, it is troublesome to use the configuration file. .. So I gave up outputting to the console and output to a file.

Be careful when specifying the log file with a relative path [2].

It seems that the default value of setLevel () in Logger is Level.INFO (information). Let's set it properly.

Source code

Log.java

public class Log {
	private static final String DEBUG_FILE = "log/test.log";
	private static final Level DEBUG_LEVEL = Level.FINER;
	public static final Logger logger = Logger.getLogger("Test");

	public Log() throws SecurityException, IOException {
		
		logger.setLevel(Level.ALL);

		FileHandler debugHandler = new FileHandler(DEBUG_FILE, APPEND);
		debugHandler.setLevel(DEBUG_LEVEL);
		debugHandler.setFormatter(new MyFormatter());
		logger.addHandler(debugHandler);

		logger.setUseParentHandlers(false);

		test();
	}

	private static void test() {
		File file = new File(DEBUG_FILE);
        if (file.exists()) {
            System.out.println("logfile: " + file.getAbsolutePath());
        } else {
            System.out.println("logfile is not exist");
        }
		logger.finest("log test: FINEST");
		logger.finer("log test: FINER");
		logger.fine("log test: FINE");
		logger.config("log test: CONFIG");
		logger.info("log test: INFO");
		logger.warning("log test: WARNING");
		logger.severe("log test: SEVERE");
	}
}

By the way, the MyFormatter class is a self-made class that inherits java.util.logging.Formatter.

How to use

new Log();

Initialize with and where you want to output the log

Log.logger.fine("Log message");

I do.

reference

[1] Tomcat, Eclipse and logs https://qiita.com/utisam/items/e725ccff4062f3078ad9 [2] Relative path when running Tomcat on Eclipse https://qiita.com/milmilk/private/99102afbb678b8e82c4c [3] [Introduction to Java] How to use Logger (explains log level and output destination settings) https://www.sejuku.net/blog/61048 [4] How to use java.util.logging https://qiita.com/Qui/items/40077ce9e33738dd3914

[^ 1]: Eclipse + Tomcat app https://searchman.info/java_eclipse/1100.html