总结

1. 对于null和空字符串，isEmpty() 和 isBlank() 效果是一样的
2. 对于全部是空格或者制表符等不可见字符的字符串，isEmpty判断为fasle, isBlank判断为true

测试代码

    @Testpublic void stringBlankTest(){String s1 = null;String s2 = "";String s3 = " ";log.info("blank for null :{}", StringUtils.isBlank(s1)); // CommonTest - blank for null :truelog.info("empty for null :{}", StringUtils.isEmpty(s1)); // CommonTest - empty for null :truelog.info("blank for '' :{}", StringUtils.isBlank(s2)); // CommonTest - blank for '' :truelog.info("empty for '' :{}", StringUtils.isEmpty(s2)); // CommonTest - empty for '' :truelog.info("blank for ' ' :{}", StringUtils.isBlank(s3)); // CommonTest - blank for ' ' :truelog.info("empty for ' ' :{}", StringUtils.isEmpty(s3)); // CommonTest - empty for ' ' :false}