com.brienwheeler.lib.validation.MessageSourceMessageInterpolator.java Source code

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Here is the source code for com.brienwheeler.lib.validation.MessageSourceMessageInterpolator.java

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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2013 Brien L. Wheeler (brienwheeler@yahoo.com)
 *
 * 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.brienwheeler.lib.validation;

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

import javax.validation.MessageInterpolator;

import org.springframework.beans.factory.annotation.Required;
import org.springframework.context.MessageSource;

/**
 * Some of this borrowed from Hibernate's ResourceBundleMessageInterpolator.
 * 
 * @author bwheeler
 */
public class MessageSourceMessageInterpolator implements MessageInterpolator {
    /**
     * Regular expression used to do message interpolation.
     */
    private static final Pattern messageParameterPattern = Pattern.compile("(\\{[^\\}]+?\\})");

    /**
     * Underlying MessageSource for resolving strings
     */
    private MessageSource messageSource;

    @Required
    public void setMessageSource(MessageSource messageSource) {
        this.messageSource = messageSource;
    }

    @Override
    public String interpolate(String messageTemplate, Context context) {
        return interpolate(messageTemplate, context, Locale.getDefault());
    }

    @Override
    public String interpolate(String messageTemplate, Context context, Locale locale) {
        String resolvedMessage = messageSource.getMessage(messageTemplate, null, locale);

        // replaceVariables
        Matcher matcher = messageParameterPattern.matcher(resolvedMessage);
        StringBuffer sb = new StringBuffer();
        String resolvedParameterValue;
        while (matcher.find()) {
            String parameterValue = removeCurlyBraces(matcher.group(1));

            // first check the annotation constraints
            Object constraintValue = context.getConstraintDescriptor().getAttributes().get(parameterValue);
            if (constraintValue != null)
                parameterValue = constraintValue.toString();

            // recurse back to MessageSource to find replacement value 
            resolvedParameterValue = interpolate(parameterValue, context, locale);
            matcher.appendReplacement(sb, escapeMetaCharacters(resolvedParameterValue));
        }
        matcher.appendTail(sb);
        resolvedMessage = sb.toString();

        // last but not least we have to take care of escaped literals
        resolvedMessage = resolvedMessage.replace("\\{", "{");
        resolvedMessage = resolvedMessage.replace("\\}", "}");
        resolvedMessage = resolvedMessage.replace("\\\\", "\\");
        return resolvedMessage;
    }

    /**
     * @param s The string in which to replace the meta characters '$' and '\'.
     *
     * @return A string where meta characters relevant for {@link Matcher#appendReplacement} are escaped.
     */
    private String escapeMetaCharacters(String s) {
        String escapedString = s.replace("\\", "\\\\");
        escapedString = escapedString.replace("$", "\\$");
        return escapedString;
    }

    private String removeCurlyBraces(String parameter) {
        return parameter.substring(1, parameter.length() - 1);
    }
}