AnsiColoring

First see the example:

import jlibs.core.lang.Ansi;

Ansi ansi = new Ansi(Ansi.Attribute.BRIGHT, Ansi.Color.BLUE, Ansi.Color.WHITE);
ansi.out("hello ansi world");

will produce following output:

Ansi:

jlibs.core.lang.Ansi constains two enums one for attributes and another for colors;

Ansi.Attribute enum contains various attributes like BRIGHT, DIM, UNDERLINE etc,.
Ansi.Color enum contains various colors like BLACK, RED, GREEN etc,.

The constructor of Ansi is of the following form:

public Ansi(Attribute attr, Color foreground, Color background)

all arguments can take null. for example if forground is null, it won't change foreground color.

Wrapping a string with special ansi control sequences and printing onto ansi supported console will result the ansi colors shown.

String msg = ansi.colorize("hello ansi world"); // msg is original string wrapped with ansi control sequences

System.out.println(msg);

The above code will print hello ansi world in specified ansi format.

the above two lines can be replaced with Ansi.out(...) as follows:

ansi.out("hello ansi world");

similarly there are various handy methods provided in Ansi:

Ansi.outln(String msg); // print given msg to console in ansi format followed by new line

Ansi.outFormat(String format, Object... args)



// to print to System.err

Ansi.err(String msg);

Ansi.errln(String msg);

Ansi.errFormat(String format, Object... args);

Ansi Support:

Ansi might not be supported on all systems. Ansi is mostly supported by all unix operating systems.

Ansi.SUPPORTED is a final boolean, that can be used to check whether your console supports Ansi format;

Ansi class uses simple checks to decide whether ansi is supported or not. Sometimes it may do wrong guess. In such cases you can override its decision using following system property:

-DAnsi=true

or

-DAnsi=false

if Ansi.SUPPORTED is false, any ansi method will not produce ansi control sequences. so you can safely use:

ansi.out("hello ansi world");

irrespective of ansi is supported or not. if ansi is not supported, this will simply do System.out.print("hello ansi world")

Ansi Formatter:

JLibs provides an implementation of java.util.logging.Formatter, to use ansi in logging. This class is:

jlibs.core.util.logging.AnsiFormatter;

Let us see usage of AnsiFormatter:

Logger logger = LogManager.getLogManager().getLogger("");

logger.setLevel(Level.FINEST);



Handler handler = logger.getHandlers()[0];

handler.setLevel(Level.FINEST);

handler.setFormatter(new AnsiFormatter());



for(Level level: map.keySet())

    logger.log(level, "this is "+level+" message");

will produce following output:

AnsiFormatter has public constants to access Ansi instance used for each level:

public class AnsiFormatter extends Formatter{

    public static final Ansi SEVERE;

    public static final Ansi WARNING;

    public static final Ansi INFO;

    public static final Ansi CONFIG;

    public static final Ansi FINE;

    public static final Ansi FINER;

    public static final Ansi FINEST;



    ...

}

These constants are made public, so that you can use them any where. for example you can do:

import static jlibs.core.util.logging.AnsiFormatter.*;



SEVERE.out("User authentication failed");

The colors used by AnsiFormatter for any level can be changed to match you taste. To do this you need to create a properties file. for example:

# myansi.properties



SEVERE=DIM;RED;GREEN

WARNING=BRIGHT;RED;YELLOW

Now use following system property:

-Dansiformatter.default=/path/to/myansi.properties

Each entry in this property file is to be given as below:

key will be the level name;
value is semicolon(;) separated values, where each argument is considered as argument to Ansi class constructor.

if any agument is null, you still need to specify empty argument. for example:

SEVERE=DIM;;GREEN # foreground is not specified

In your properties file, you don't need to specify entries for each level. you can specify entries only for those levels that you want to change;

Your comments are welcomed.