java正则表达式匹配

package offer;/* * 字符串匹配 * "."匹配任意一个字符 * "*"表示前面的字符出现任意次 */public class Match {    public static void main(String[] args) {        String str = "aaa";        String pattern = "b*aaaa*a*a*a*.*";        System.out.println(match(str, 0, pattern, 0));    }    private static boolean match(String str, int strIndex, String pattern, int patternIndex) {        //出口1 ：两个字符串都到达了结尾，说明匹配成功，返回true        if (strIndex >= str.length() && patternIndex >= pattern.length()) {            return true;        }        //出口2 ：模式串达到了结尾，说明匹配失败，返回false        if (strIndex != str.length() && patternIndex >= pattern.length()) {            return false;        }        //若下一个字符为'*'        if (patternIndex + 1 < pattern.length() && pattern.charAt(patternIndex + 1) == '*') {            if(strIndex >= str.length()){                  //若匹配串已经结束                  return match(str, strIndex, pattern, patternIndex + 2);            } else {                if (str.charAt(strIndex) == pattern.charAt(patternIndex) || (pattern.charAt(patternIndex) == '.' && strIndex != str.length()) ) {                    return match(str, strIndex, pattern, patternIndex + 2)                            ||match(str, strIndex + 1, pattern, patternIndex + 2)                            ||match(str, strIndex + 1, pattern, patternIndex);                } else {                    return match(str, strIndex, pattern, patternIndex + 2);                }            }        }        //若当前字符为'.'        if(strIndex >= str.length()){             //若匹配串已经结束              return false;        } else{            if (str.charAt(strIndex) == pattern.charAt(patternIndex) || pattern.charAt(patternIndex) == '.') {                return match(str, strIndex + 1, pattern, patternIndex + 1);            }        }        return false;    }}