public static void main(String[] args) {
        String s = null;
        System.out.println(org.apache.commons.lang3.StringUtils.isBlank(s));//true
        System.out.println(org.apache.commons.lang3.StringUtils.isBlank(new String("")));//true
        System.out.println(org.apache.commons.lang3.StringUtils.isBlank(new String("     ")));//空格 true

        System.out.println(org.apache.commons.lang.StringUtils.isBlank(s));//true
        System.out.println(org.apache.commons.lang.StringUtils.isBlank(new String("")));//true
        System.out.println(org.apache.commons.lang.StringUtils.isBlank(new String("     ")));//空格 true
    }
 

這兩個類的isBlank原始碼是類似的