匹配“大写字母，小写字母，数字，特殊字符”四项中的至少三项的正则表达式如下：
“^(?![a-zA-Z]+$)(?![A-Z0-9]+$)(?![A-Z\\W_!@#$%^&*`~()-+=]+$)(?![a-z0-9]+$)(?![a-z\\W_!@#$%^&*`~()-+=]+$)(?![0-9\\W_!@#$%^&*`~()-+=]+$)[a-zA-Z0-9\\W_!@#$%^&*`~()-+=]{8,30}$”
正则代码生成网站：
http://tool.chinaz.com/tools/regexgenerate
import java.util.regex.Matcher;import java.util.regex.Pattern;public class RegexMatches { public static void main(String args[]) { String str = ""; String pattern = "^(?![a-zA-Z]+$)(?![A-Z0-9]+$)(?![A-Z\\W_!@#$%^&*`~()-+=]+$)(?![a-z0-9]+$)(?![a-z\\W_!@#$%^&*`~()-+=]+$)(?![0-9\\W_!@#$%^&*`~()-+=]+$)[a-zA-Z0-9\\W_!@#$%^&*`~()-+=]{6,30}$"; Pattern r = Pattern.compile(pattern); Matcher m = r.matcher(str); System.out.println(m.matches()); }}
