StringUtils中的isEmpty、isNotEmpty、isAnyEmpty、 isNoneEmpty、isBlank、isNotBlank、isAnyBlank、isNoneBlank

前言

今天网上冲浪时，看到org.apache.commons.lang3.StringUtils工具类的isEmpty方法，就想到了isBlank这个方法，去做个笔记记录一下这两个系列的方法

一、isEmpty系列

1.StringUtils.isEmpty(),源码如下

    /**
     * <p>Checks if a CharSequence is empty ("") or null.</p>
     *
     * <pre>
     * StringUtils.isEmpty(null)      = true
     * StringUtils.isEmpty("")        = true
     * StringUtils.isEmpty(" ")       = false
     * StringUtils.isEmpty("bob")     = false
     * StringUtils.isEmpty("  bob  ") = false
     * </pre>
     *
     * <p>NOTE: This method changed in Lang version 2.0.
     * It no longer trims the CharSequence.
     * That functionality is available in isBlank().</p>
     *
     * @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;
    }

 可以看到 " " 空格是会绕过这种空判断,因为是一个空格,并不是严格的空值,会导致 isEmpty(" ")=false

2.StringUtils.isNotEmpty()方法，源码如下

　　/**
     * <p>Checks if a CharSequence is not empty ("") and not null.</p>
     *
     * <pre>
     * StringUtils.isNotEmpty(null)      = false
     * StringUtils.isNotEmpty("")        = false
     * StringUtils.isNotEmpty(" ")       = true
     * StringUtils.isNotEmpty("bob")     = true
     * StringUtils.isNotEmpty("  bob  ") = true
     * </pre>
     *
     * @param cs  the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is not empty and not null
     * @since 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)
     */
    public static boolean isNotEmpty(final CharSequence cs) {
        return !isEmpty(cs);
    }

判断字符串不为空 , 相当于!isEmpty(ss)方法

3. StringUtils.isAnyEmpty()方法源码如下

　　/**
     * <p>Checks if any one of the CharSequences are empty ("") or null.</p>
     *
     * <pre>
     * StringUtils.isAnyEmpty(null)             = true
     * StringUtils.isAnyEmpty(null, "foo")      = true
     * StringUtils.isAnyEmpty("", "bar")        = true
     * StringUtils.isAnyEmpty("bob", "")        = true
     * StringUtils.isAnyEmpty("  bob  ", null)  = true
     * StringUtils.isAnyEmpty(" ", "bar")       = false
     * StringUtils.isAnyEmpty("foo", "bar")     = false
     * </pre>
     *
     * @param css  the CharSequences to check, may be null or empty
     * @return {@code true} if any of the CharSequences are empty or null
     * @since 3.2
     */
    public static boolean isAnyEmpty(final CharSequence... css) {
      if (ArrayUtils.isEmpty(css)) {
        return true;
      }
      for (final CharSequence cs : css){
        if (isEmpty(cs)) {
          return true;
        }
      }
      return false;
    }

是否有一个为空,只有一个为空,就为true.

4. StringUtils.isNoneEmpty()方法，源码如下

　　 /**
     * <p>Checks if none of the CharSequences are empty ("") or null.</p>
     *
     * <pre>
     * StringUtils.isNoneEmpty(null)             = false
     * StringUtils.isNoneEmpty(null, "foo")      = false
     * StringUtils.isNoneEmpty("", "bar")        = false
     * StringUtils.isNoneEmpty("bob", "")        = false
     * StringUtils.isNoneEmpty("  bob  ", null)  = false
     * StringUtils.isNoneEmpty(" ", "bar")       = true
     * StringUtils.isNoneEmpty("foo", "bar")     = true
     * </pre>
     *
     * @param css  the CharSequences to check, may be null or empty
     * @return {@code true} if none of the CharSequences are empty or null
     * @since 3.2
     */
    public static boolean isNoneEmpty(final CharSequence... css) {
      return !isAnyEmpty(css);
    }

必须所有的值都不为空才返回true，相当于!isAnyEmpty() , 

二、isBank系列

1. StringUtils.isBlank()方法，源码如下

　　/**
     * <p>Checks if a CharSequence is whitespace, empty ("") or null.</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
     * @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)) == false) {
                return false;
            }
        }
        return true;
    }

 是否为真空值(空格或者空值)，isBlank()判断了空格的存在

2. StringUtils.isNotBlank()，源码如下

 

 　　/**
     * <p>Checks if a CharSequence is not empty (""), not null and not whitespace only.</p>
     *
     * <pre>
     * StringUtils.isNotBlank(null)      = false
     * StringUtils.isNotBlank("")        = false
     * StringUtils.isNotBlank(" ")       = false
     * StringUtils.isNotBlank("bob")     = true
     * StringUtils.isNotBlank("  bob  ") = true
     * </pre>
     *
     * @param cs  the CharSequence to check, may be null
     * @return {@code true} if the CharSequence is
     *  not empty and not null and not whitespace
     * @since 2.0
     * @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
     */
    public static boolean isNotBlank(final CharSequence cs) {
        return !isBlank(cs);
    }

是否真的不为空,不是空格或者空值 ,相当于!isBlank();

3. StringUtils.isAnyBlank()，源码如下

 

　　/**
     * <p>Checks if any one of the CharSequences are blank ("") or null and not whitespace only..</p>
     *
     * <pre>
     * StringUtils.isAnyBlank(null)             = true
     * StringUtils.isAnyBlank(null, "foo")      = true
     * StringUtils.isAnyBlank(null, null)       = true
     * StringUtils.isAnyBlank("", "bar")        = true
     * StringUtils.isAnyBlank("bob", "")        = true
     * StringUtils.isAnyBlank("  bob  ", null)  = true
     * StringUtils.isAnyBlank(" ", "bar")       = true
     * StringUtils.isAnyBlank("foo", "bar")     = false
     * </pre>
     *
     * @param css  the CharSequences to check, may be null or empty
     * @return {@code true} if any of the CharSequences are blank or null or whitespace only
     * @since 3.2
     */
    public static boolean isAnyBlank(final CharSequence... css) {
      if (ArrayUtils.isEmpty(css)) {
        return true;
      }
      for (final CharSequence cs : css){
        if (isBlank(cs)) {
          return true;
        }
      }
      return false;
    }

是否包含任何真空值(包含空格或空值)

4 StringUtils.isNoneBlank()，源码如下

　　/**
     * <p>Checks if none of the CharSequences are blank ("") or null and whitespace only..</p>
     *
     * <pre>
     * StringUtils.isNoneBlank(null)             = false
     * StringUtils.isNoneBlank(null, "foo")      = false
     * StringUtils.isNoneBlank(null, null)       = false
     * StringUtils.isNoneBlank("", "bar")        = false
     * StringUtils.isNoneBlank("bob", "")        = false
     * StringUtils.isNoneBlank("  bob  ", null)  = false
     * StringUtils.isNoneBlank(" ", "bar")       = false
     * StringUtils.isNoneBlank("foo", "bar")     = true
     * </pre>
     *
     * @param css  the CharSequences to check, may be null or empty
     * @return {@code true} if none of the CharSequences are blank or null or whitespace only
     * @since 3.2
     */
    public static boolean isNoneBlank(final CharSequence... css) {
      return !isAnyBlank(css);
    }

是否全部都不包含空值或空格