Struts example source code file (WildcardUtil.java)

This example Struts source code file (WildcardUtil.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

pattern, pattern, regex, string, string, stringbuilder, stringbuilder, wildcardutil, wildcardutil

The Struts WildcardUtil.java source code

/*
 * Copyright 2010 Yahoo, Inc.  All rights reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.opensymphony.xwork2.util;

import java.util.regex.Pattern;

/**
 * Helper class to convert wildcard expression to regular expression
 */
public class WildcardUtil {

    /**
     * Convert wildcard pattern to Pattern
     * @param pattern String containing wildcard pattern
     * @return compiled regular expression as a Pattern
     */
    public static Pattern compileWildcardPattern(String pattern) {
        StringBuilder buf = new StringBuilder(pattern);

        for (int i=buf.length()-1; i>=0; i--)
        {
            char c = buf.charAt(i);
            if (c == '*' && (i == 0 || buf.charAt(i-1) != '\\'))
            {
                buf.insert(i+1, '?');
                buf.insert(i, '.');
            }
            else if (c == '*')
            {
            	i--;	// skip backslash, too
            }
            else if (needsBackslashToBeLiteralInRegex(c))
            {
                buf.insert(i, '\\');
            }
        }

        return Pattern.compile(buf.toString());
    }

    /**
     * @param c character to test
     * @return true if the given character must be escaped to be a literal
     * inside a regular expression.
     */

    private static final String theSpecialRegexCharList = ".[]\\?*+{}|()^$";

    public static boolean needsBackslashToBeLiteralInRegex(
        char c)
    {
        return (theSpecialRegexCharList.indexOf(c) >= 0);
    }

}