Apache的commonslang3包StringUtils。isEmptyisBlank方法区别

　　经常使用commons-lang3包中的StringUtils判断 字符串是否为空，isEmpty、isBlank都在使用，但在使用上还有有点小小的区别的。 isEmpty源码// Empty checks //----------------------------------------------------------------------- /**  * 
Checks if a CharSequence is empty (＂＂) or null.  *  * 
  * StringUtils.isEmpty(null)      = true  * StringUtils.isEmpty(＂＂)        = true  * StringUtils.isEmpty(＂ ＂)       = false  * StringUtils.isEmpty(＂bob＂)     = false  * StringUtils.isEmpty(＂  bob  ＂) = false  * 
  *  * 
NOTE: This method changed in Lang version 2.0.  * It no longer trims the CharSequence.  * That functionality is available in isBlank().  *  * @param cs  the CharSequence to check, may be null  * @return {@code true} if the CharSequence is empty or null  * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)  */ public static boolean isEmpty(final CharSequence cs) {     return cs == null || cs.length() == 0; } isBlank源码/**  * 
Checks if a CharSequence is empty (＂＂), null or whitespace only.  *  * 
Whitespace is defined by {@link Character#isWhitespace(char)}.  *  * 
  * StringUtils.isBlank(null)      = true  * StringUtils.isBlank(＂＂)        = true  * StringUtils.isBlank(＂ ＂)       = true  * StringUtils.isBlank(＂bob＂)     = false  * StringUtils.isBlank(＂  bob  ＂) = false  * 
  *  * @param cs  the CharSequence to check, may be null  * @return {@code true} if the CharSequence is null, empty or whitespace only  * @since 2.0  * @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)  */ 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; } 区别for (int i = 0; i < strLen; i++) {     if (!Character.isWhitespace(cs.charAt(i))) {         return false;     } }
　　isBlank多了一个循环，循环入参中的字符串，若有一个字符不是空，入参字符串不为空，当入参字符串中每个字符都是空格时，isBlank也返回true。
　　即，针对同一个字符串＂ ＂（中间是英文空格），两个方法返回值不一样，isEmpty 返回 false，而 isBlank 则返回 true.