ww1ww1 wrote:
How to got this e-version of O'Reilly - Mastering Regular Expressions(2nd) ?

why wrote:
Please do a search on Google.
The first edition is good enough
I found this on the first result page
http://bookshelf.sleepnet.net/files/%5Bebook%5D%20OReilly%20-%20Mastering%20Regular%20Expressions.pdf

ww1ww1 wrote:
But I wonder how could you find that link,
as I search the key word " Mastering Regular Expressions" with Google, it just return some links which link to some bookshops or introduction of that book.

import java.util.regex.*;

public class VerifyTool {
  private static Pattern emailPattern = null;
  private VerifyTool() {
  }
  /**
   * 检验一个字符串是否是合法的Email地址。
   * @param aString String
   * @return boolean
   */
  public static boolean isValidEmail(String aString) {
    if (aString == null || aString.length() < 9) {
      //至少应该五个字符比如：a@b.c ，但是一般来说9个字母的email地址都不存在。
      //因为根据域名规则，'@'后面至少应该有6位(比如aaa.cn，
      //根域名至少两个字符,且只能够是字母。顶级域名至少3个字符，加是分隔符，就是6个字符了
      //用户名只有一位或者两位的基本没有，可以当作不存在的用户)
      return false;
    }
    if (emailPattern == null) {
      emailPattern = Pattern.compile(
          "^[\\w-.]+@([\\w-]+.)*([\\w-]{3,20}+.)+[a-zA-Z]{2,4}$");
    }
    return emailPattern.matcher(aString).find();
  }
}