public static boolean isBlank(final CharSequence cs) {
        int strLen;
        if (cs == null || (strLen = cs.length()) == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(cs.charAt(i))) {
                return false;
            }
        }
        return true;
    }
<p>Checks if a CharSequence is empty (""), null or whitespace only.</p>

<p>Whitespace is defined by {@link Character#isWhitespace(char)}.</p>

<pre>
StringUtils.isBlank(null)      = true
StringUtils.isBlank("")        = true
StringUtils.isBlank(" ")       = true
StringUtils.isBlank("bob")     = false
StringUtils.isBlank("  bob  ") = false
</pre>

@param cs the CharSequence to check, may be null
@return {@code true} if the CharSequence is null, empty or whitespace only
fastexcel-core/src/main/java/cn/idev/excel/util/StringUtils.java