字符串操作之 ==> apache.commons.lang3.StringUtils

一、常用方法

1、判断是否为空串

isBlank(final CharSequence cs)：判断是否为空字符串；
isEmpty(final CharSequence cs)：判断是否为空字符串；
isNotBlank(final CharSequence cs)：判断不是空字符串；
isNotEmpty(final CharSequence cs)：判断不是空字符串；
说明：isBlank和isEmpty的区别在于在于空格字符串的判断不同，isEmpty认为空格字符不是空字符串

StringUtils.isBlank(null);      = true
StringUtils.isBlank("");        = true
StringUtils.isBlank(" ");       = true
StringUtils.isBlank("hello");   = false
StringUtils.isBlank(" hello "); = false
---------------------------------------
StringUtils.isEmpty(null);      = true
StringUtils.isEmpty("");        = true
StringUtils.isEmpty(" ");       = false
StringUtils.isEmpty("hello");   = false
StringUtils.isEmpty(" hello "); = false
------------------------------------------
StringUtils.isNotBlank(null);      = false
StringUtils.isNotBlank("");        = false
StringUtils.isNotBlank(" ");       = false
StringUtils.isNotBlank("hello");   = true
StringUtils.isNotBlank(" hello "); = true
------------------------------------------
StringUtils.isNotEmpty(null);      = false
StringUtils.isNotEmpty("");        = false
StringUtils.isNotEmpty(" ");       = true
StringUtils.isNotEmpty("hello");   = true
StringUtils.isNotEmpty(" hello "); = true

示例

2、去除字符串前后空格及换行符

trim(final String str):去除字符串前后空格，同时不改变原字符串；
trimToNull(final String str)：去除字符串前后空格，如果去除后是空字符串就转为null；
trimToEmpty(final String str)：去除字符串前后空格，如果去除后是空字符串就转为空字符串(null转为""）;
strip(final String str)：这个也可以去除字符串的前后空格，不改变原字符串；
stripToNull(String str)：同trimToNull(final String str)类似；
stripToEmpty(final String str)：同trimToEmpty(final String str)类似；
String[] stripAll(final String... strs)：对数组中的所有字符串进行去除空格；

StringUtils.trim(" hello ");      = "hello"
StringUtils.trim("\n hello \n");  = "hello"
StringUtils.trimToNull(null);     = null
StringUtils.trimToNull("    \n"); = null
StringUtils.trimToEmpty(null);    = ""
StringUtils.trimToEmpty("\n  \n");= ""
--------------------------------------------
StringUtils.strip(" hello ");     = "hello"
StringUtils.strip("\n hello \n"); = "hello"
StringUtils.stripToNull(null);    = null
StringUtils.stripToNull("     "); = null
StringUtils.stripToEmpty(null);   = ""
StringUtils.stripToEmpty("     ");= ""
--------------------------------------------
StringUtils.stripAll(" \n abc", null, "\n aab \n"); = [abc, null, aab]

示例

3、字符串剥离

strip(String str, final String stripChars)：从str的前后剥离stripChars字符串；
stripStart(final String str, final String stripChars)：从开始的地方剥离指定字符串；
stripEnd(final String str, final String stripChars)：从结束的地方剥离字符串；
String[] stripAll(final String[] strs, final String stripChars)：对数组中的每个字符串进行字符串剥离；

StringUtils.strip("abcde", "de");        = "abc"
StringUtils.strip("abcde", "ed");        = "abc"
StringUtils.stripStart("deabced", "ed"); = "abced"
StringUtils.stripStart("deabced", "de"); = "abced"
StringUtils.stripEnd("  abcyx", "xyz");  = "  abc"
StringUtils.stripEnd("120.00", ".0");    = "12"
StringUtils.stripAll(new String[]{"aab", "abc", "aba"}, "ab"); = ["","c",""]

示例

4、字符串截取

truncate(final String str, final int maxWidth)：截取字符串的前maxWidth个字符；
如果str的长度小于maxWidth就直接返回str；
如果maxWidth小于0则抛出IllegalArgumentException异常；
truncate(final String str, final int offset, final int maxWidth)：截取指定区域的字符串；

StringUtils.truncate(null, 0);  = null
StringUtils.truncate(null, 2);  = null
StringUtils.truncate("", 4);    = ""
StringUtils.truncate("abcdefg", 4); = "abcd"
StringUtils.truncate(null, 0, 0);   = null
StringUtils.truncate(null, 2, 4);   = null
StringUtils.truncate("", 0, 10);    = ""
StringUtils.truncate("", 2, 10);    = ""
StringUtils.truncate("abcdefghij", 0, 3); = "abc"
StringUtils.truncate("abcdefghij", 5, 6); = "fghij"
StringUtils.truncate("abcdefghijklmno", -1, 10); = java.lang.IllegalArgumentException: offset cannot be negative
StringUtils.truncate("abcdefghijklmno", Integer.MIN_VALUE, 10); = java.lang.IllegalArgumentException: offset cannot be negative
StringUtils.truncate("abcdefghijklmno", 0, Integer.MAX_VALUE);  = "abcdefghijklmno"

示例

5、字符串比较

equals(final CharSequence cs1, final CharSequence cs2):判断两个字符串是否相等；
equalsIgnoreCase(final CharSequence str1, final CharSequence str2)：判断两个字符串在忽略大小写下是否相等；
compare(final String str1, final String str2)：比较两个字符串的大小；
compareIgnoreCase(final String str1, final String str2)：忽略大小写下比较两个字符串的大小；
equalsAny(final CharSequence string, final CharSequence... searchStrings):比较多字符串中是否存在相同的字符串；
equalsAnyIgnoreCase(final CharSequence string, final CharSequence...searchStrings)：忽略大小写是否存在相同字符；

StringUtils.equals("abc", null);  = false
StringUtils.equals("abc", "abc"); = true
StringUtils.equals("abc", "ABC"); = false
StringUtils.equalsIgnoreCase("abc", "ABC"); = true
--------------------------------------------------
StringUtils.compare("abc", "abc");          = 0
StringUtils.compare("a", "b");              = -1
StringUtils.compare("b", "a");              = 1
StringUtils.compare("a", "B");              = 31
StringUtils.compare("ab", "abc");           = -1
StringUtils.compareIgnoreCase("a", "B");    = -1
StringUtils.compareIgnoreCase("A", "b");    = -1
StringUtils.compareIgnoreCase("ab", "ABC"); = -1
--------------------------------------------------
StringUtils.equalsAny("abc", "abc", "def"); = true
StringUtils.equalsAny("abc", "ABC", "DEF"); = false
StringUtils.equalsAnyIgnoreCase("abc", "abc", "def"); = true
StringUtils.equalsAnyIgnoreCase("abc", "ABC", "DEF"); = true

示例

6、字符串查找

indexOf(final CharSequence seq, final int searchChar)：查找指定字符在字符串中首次出现的位置的索引值；
indexOf(final CharSequence seq, final int searchChar, final int startPos)：从指定位置final int startPos开始查找；
indexOfIgnoreCase(final CharSequence str, final CharSequence searchStr)：忽略大小写的查找字符串首次出现位置
indexOfIgnoreCase(final CharSequence str, final CharSequence searchStr, int startPos)：同`indexOf类似；
lastIndexOf(final CharSequence seq, final int searchChar)：从尾部开始查找；
lastIndexOf(final CharSequence seq, final int searchChar, final int startPos)：同理从尾部开始查找指定位置前的字符；

StringUtils.indexOf("aabaabaa", 'b');    = 2
StringUtils.indexOf("aabaabaa", "");     = 0
StringUtils.indexOf("aabaabaa", "b", 3); = 5
StringUtils.indexOfIgnoreCase("aabaabaa", "B");    = 2
StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3); = 5
StringUtils.ordinalIndexOf("abababab", "abab", 3); = 4
StringUtils.lastIndexOf("aabaabaa", 'b');    = 5
StringUtils.lastIndexOf("aabaabaa", 'b', 4); = 0

示例

7、是否包含字符串

contains(final CharSequence seq, final int searchChar：是否包含指定字符串；
containsIgnoreCase(final CharSequence str, final CharSequence searchStr：忽略大小写下检查是否包含指定字符串
containsWhitespace(final CharSequence seq)：是否包含空白字符串；
containsAny(final CharSequence cs, final char... searchChars)：判断字符窜是否包含后面多个中的任意一个；
containsOnly(final CharSequence cs, final char... valid)：判断前面的字符是否全部是后面的字符组成的；
containsNone(final CharSequence cs, final char... searchChars)：判断前面字符是否不含其后字符的任意一个字符;

StringUtils.contains("abc", "a");  = true
StringUtils.contains("abc", 'z');  = false
StringUtils.containsIgnoreCase("abc", "A");      = true
StringUtils.containsIgnoreCase("abc", "Z");      = false
StringUtils.containsWhitespace("abc");           = false
StringUtils.containsWhitespace("a  bc");         = true
StringUtils.containsAny("zzabyycdxx", 'a', 'f'); = true
StringUtils.containsAny("zzabyycdxx", 'b', 'y'); = true
StringUtils.containsAny("zzabyycdxx", 'z', 'y'); = true
StringUtils.containsAny("aba", 'z');             = false
StringUtils.containsOnly("abab", 'a', 'b', 'c'); = true
StringUtils.containsOnly("ab1", "abc");          = false
StringUtils.containsOnly("abz", 'a', 'b', 'c');  = false
StringUtils.containsNone("abab", "ab");          = false
StringUtils.containsNone("ab1", 'x', 'y', 'z');  = true
StringUtils.containsNone("abz", "xyz");          = false

示例

8、截取字符串

substring(final String str, int start)：指定开始为止截取字符串；
String substring(final String str, int start, int end):指定开始和结束为止截取字符串；
left(final String str, final int len)：得到一个字符串最左边的len个字符；
right(final String str, final int len)：得到一个字符串最右边的len个字符；
mid(final String str, int pos, final int len)：得到中间的指定区域的字符，是左包含；
substringBefore(final String str, final String separator)：得到一个字符串中第一个分割符之前的字符串；
substringAfter(final String str, final String separator)：同理，得到一个字符串第一个分割符之后的字符串；

StringUtils.substring("abc", 2);        = "c"
StringUtils.substring("abc", 4);        = ""
StringUtils.substring("abc", -2);       = "bc"
StringUtils.substring("abc", -4);       = "abc"
StringUtils.substring("abc", 2, 2);     = ""
StringUtils.substring("abc", -2, -1);   = "b"
StringUtils.substring("abc", -4, 2);    = "ab"
StringUtils.left("abc", 2);     = "ab"
StringUtils.left("abc", 4);     = "abc"
StringUtils.right("abc", 2);    = "bc"
StringUtils.right("abc", 4);    = "abc"
StringUtils.mid("abc", 2, 4);   = "c"
StringUtils.mid("abc", 4, 2);   = ""
StringUtils.mid("abc", -2, 2);  = "ab"
StringUtils.substringBefore("abcba", "b"); = "a"
StringUtils.substringBefore("abc", "c");   = "ab"
StringUtils.substringBefore("abc", "d");   = "abc"
StringUtils.substringAfter("abcba", "b");  = "cba"
StringUtils.substringAfter("abc", "c");    = ""
StringUtils.substringAfter("abc", "d");    = ""

示例

9、字符串分割

String[] split(final String str)：按照空格分割字符串，返回数组；
String[] split(final String str, final char separatorChar)：指定分割符分割字符串；
String[] split(final String str, final String separatorChars, final int max)：指定分割符，指定最大分割的数组大小;
String[] splitByCharacterTypeCamelCase(final String str)：根据字符串类型分割字符串；

StringUtils.split("abc  def");    = ["abc","def"]
StringUtils.split(" abc ");       = ["abc"]
StringUtils.split("a,,b,c", ','); = ["a","b","c"]
StringUtils.split("a:b:c", '.');  = ["a:b:c"]
StringUtils.split("a b c", ' ');  = ["a","b","c"]
StringUtils.split("ab:cd:ef", ":", 3); = ["ab","cd","ef"]
StringUtils.split("ab:cd:ef", ":", 2); = ["ab","cd:ef"]
StringUtils.split("ab:cd:ef", ":", 1); = ["ab:cd:ef"]
StringUtils.splitByCharacterTypeCamelCase("number5");   = ["number","5"]
StringUtils.splitByCharacterTypeCamelCase("fooBar");    = ["foo","Bar"]
StringUtils.splitByCharacterTypeCamelCase("foo200Bar"); = ["foo","200","Bar"]
StringUtils.splitByCharacterTypeCamelCase("ASFRules");  = ["ASF","Rules"]

示例

10、字符串拼接

join(final T... elements)；普通的连接字符串
join(final Object[] array, final char separator)：指定连接符，连接字符串；

StringUtils.join("a", "b", "c");  = "abc"
StringUtils.join(null, "", "a");  = "a"
StringUtils.join(new String[]{"a", "b", "c"}, ';');  = "a;b;c"
StringUtils.join(new String[]{"a", "b", "c"}, null); = "abc"
StringUtils.join(new String[]{null, "", "a"}, ';');  = ";;a"

示例

11、删除和替换字符串

removeStart(final String str, final String remove)：删除字符串中的指定的前缀字符串；
removeStartIgnoreCase(final String str, final String remove)：同removeStart类似，只是忽略的大小写；
removeEnd(final String str, final String remove)：同removeStart相反；
deleteWhitespace(final String str)：删除字符串中的空格；
remove(final String str, final String remove)：从字符串中移除指定字符串；
removeAll(final String text, final String regex)：移除符合正则表达式的所有字符串；
replaceOnce(final String text, final String searchString, final String replacement)：将字符串中指定字符替换一个；
replaceAll(final String text, final String regex, final String replacement)：将字符串中指定字符替换所有；

StringUtils.removeStart("www.domain.com", "www.");   = "domain.com"
StringUtils.removeStart("domain.com", "www.");       = "domain.com"
StringUtils.removeStart("www.domain.com", "domain"); = "www.domain.com"
StringUtils.removeStart("abc", "");                  = "abc"
StringUtils.deleteWhitespace("abc");                 = "abc"
StringUtils.deleteWhitespace("   ab  c  ");          = "abc"
StringUtils.removeEnd("www.domain.com", ".com.");    = "www.domain.com"
StringUtils.removeEnd("www.domain.com", ".com");     = "www.domain"
StringUtils.removeEnd("www.domain.com", "domain");   = "www.domain.com"
StringUtils.remove("queued", "ue");        = "qd"
StringUtils.remove("queued", "zz");        = "queued"
StringUtils.replaceOnce("aba", "a", null); = "aba"
StringUtils.replaceOnce("aba", "a", "");   = "ba"
StringUtils.replaceOnce("aba", "a", "z");  = "zba"
StringUtils.replaceAll("aba", "a", "z");  = "zbz"

示例

12、生成重复字符串

repeat(final String str, final int repeat)：生成指定重复次数的重复字符串；

StringUtils.repeat("a", 3);  = "aaa"
StringUtils.repeat("ab", 2); = "abab"
StringUtils.repeat("a", -2); = ""

示例

13、字符串出现次数

countMatches(final CharSequence str, final CharSequence sub)：获取指定字符串在原字符串中出现的次数；

StringUtils.countMatches("abba", "a");  = 2
StringUtils.countMatches("abba", "ab"); = 1

示例

二、其他方法

1、判断是否是空格

isWhitespace(final CharSequence cs)

StringUtils.isWhitespace("");    = true
StringUtils.isWhitespace("  ");  = true
StringUtils.isWhitespace("abc"); = false

示例

2、判断字符串是否由空格或者数字组成

isNumericSpace(final CharSequence cs)

StringUtils.isNumericSpace("12 3");  = true
StringUtils.isNumericSpace("12.3");  = false

示例

3、判断是否全是小写/大写

isAllLowerCase(final CharSequence cs)
isAllUpperCase(final CharSequence cs)

StringUtils.isAllLowerCase("abc");  = true
StringUtils.isAllLowerCase("abC");  = false
StringUtils.isAllUpperCase("ABC");  = true
StringUtils.isAllUpperCase("aBC");  = false

示例

4、判断字符串是否以什么开头/结尾

startsWith(final CharSequence str, final CharSequence prefix)
endsWith(final CharSequence str, final CharSequence suffix)

StringUtils.startsWith("abcdef", null);  = false
StringUtils.startsWith("abcdef", "abc"); = true
StringUtils.startsWith("ABCDEF", "abc"); = false
StringUtils.endsWith("ABCDEF", "def");   = false
StringUtils.endsWith("ABCDEF", "cde");   = false
StringUtils.endsWith("ABCDEF", "DEF");   = true

示例

5、字符串反转

reverse(final String str)

StringUtils.reverse("bat"); = "tab"

示例

posted on 2020-05-28 17:19 破解孤独阅读(1151) 评论(0) 编辑收藏举报

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