代码中一些常见的小片段

1,检验邮件格式是否正确

public final static String REG_email = "^[\w\d]+@[\w\d]+(\.[\w\d]+)+$";
Pattern pattern = Pattern.compile(RegExpression.REG_email);
Matcher m = pattern.matcher(email);
if (!m.find()) {
　　System.out.println("Wrong email format.");
}