字符串正则化类
public class StringNormalize {public static String normalize(String in) {StringBuilder out = new StringBuilder();String l = in.toLowerCase();for (int i = 0; i < l.length(); ++i) {char c = l.charAt(i);if (c >= 'a' && c <= 'z' || c >= '0' && c <= '9') {out.append(c);}}return out.toString();}}
