com.yukthi.utils.MessageFormatter.java Source code

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Here is the source code for com.yukthi.utils.MessageFormatter.java

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/*
 * The MIT License (MIT)
 * Copyright (c) 2015 "Yukthi Techsoft Pvt. Ltd." (http://yukthi-tech.co.in)
    
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.yukthi.utils;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang.StringUtils;

/**
 * Utility to format strings in log4j 2 way.
 * 
 * {} will match with the current index argument. If index is greater than provided values then <undefined> string will be used.
 * {<idx>} can be used to refer to argument at particular index. Helpful in building messages which uses same argument multiple times.
 * 
 * @author akiran
 */
public class MessageFormatter {
    /**
     * String that will be used when argument index is out of range
     */
    public static final String UNDEFINED = "<undefined>";

    /**
     * Param argument pattern
     */
    private static final Pattern PARAM_PATTERN = Pattern.compile("\\{(\\d*)\\}");

    /**
     * Replaces the args values in "message" using patterns mentioned below and same will be returned. 
     * 
     * {} will match with the current index argument. If index is greater than provided values then &lt;undefined&gt; string will be used.
     * {&lt;idx&gt;} can be used to refer to argument at particular index. Helpful in building messages which uses same argument multiple times.
     * 
     * @param message Message string with expressions
     * @param args Values for expression
     * @return Formatted string
     */
    public static String format(String message, Object... args) {
        //when message is null, return null
        if (message == null) {
            return null;
        }

        //when args is null, assume empty values
        if (args == null) {
            args = new Object[0];
        }

        Matcher matcher = PARAM_PATTERN.matcher(message);
        StringBuffer buffer = new StringBuffer();

        int loopIndex = 0;
        int argIndex = 0;
        Object arg = null;

        //loop through pattern matches
        while (matcher.find()) {
            //if index is mentioned in pattern
            if (StringUtils.isNotBlank(matcher.group(1))) {
                argIndex = Integer.parseInt(matcher.group(1));
            }
            //if index is not specified, use current loop index
            else {
                argIndex = loopIndex;
            }

            //if the index is within provided arguments length
            if (argIndex < args.length) {
                arg = args[argIndex];
            }
            //if the index is greater than available values
            else {
                arg = UNDEFINED;
            }

            //if argument value is null
            if (arg == null) {
                arg = "null";
            }

            matcher.appendReplacement(buffer, arg.toString());
            loopIndex++;
        }

        matcher.appendTail(buffer);
        return buffer.toString();
    }
}