判断用户名只支持中英文和下划线

public static boolean checkLetterInvalid(String s)

{

char[] cs = s.toCharArray();

boolean flag = true;

for(char c:cs)

{

if(Character.isDigit(c))

{

continue;

}

if(Character.isLetter(c))

{

continue;

}

if(c == 95)

{

continue;

}

Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);

if(ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS)

{

continue;

}

flag = false;

break;

}

return flag;

}