字符串工具类

abbreviate(String str, int maxWidth) 返回一个指定长度加省略号的字符串，maxWidth必须大于3

StringUtils.abbreviate(null, *)      = nullStringUtils.abbreviate("", 4)        = ""StringUtils.abbreviate("abcdefg", 6) = "abc..."StringUtils.abbreviate("abcdefg", 7) = "abcdefg"StringUtils.abbreviate("abcdefg", 8) = "abcdefg"StringUtils.abbreviate("abcdefg", 4) = "a..."StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException

abbreviate(String str, int offset, int maxWidth) 返回一个指定长度加省略号的字符串，maxWidth必须大于3

abbreviate(String str, String abbrevMarker, int maxWidth) 返回一个自定义省略号的指定长度字符串，maxWidth必须大于3

StringUtils.abbreviate(null, "...", *)      = nullStringUtils.abbreviate("abcdefg", null, *)  = "abcdefg"StringUtils.abbreviate("", "...", 4)        = ""StringUtils.abbreviate("abcdefg", ".", 5)   = "abcd."StringUtils.abbreviate("abcdefg", ".", 7)   = "abcdefg"StringUtils.abbreviate("abcdefg", ".", 8)   = "abcdefg"StringUtils.abbreviate("abcdefg", "..", 4)  = "ab.."StringUtils.abbreviate("abcdefg", "..", 3)  = "a.."StringUtils.abbreviate("abcdefg", "..", 2)  = IllegalArgumentExceptionStringUtils.abbreviate("abcdefg", "...", 3) = IllegalArgumentException

abbreviateMiddle(String str, String abbrevMarker, int maxWidth) 将字符串缩短到指定长度（length），字符串的中间部分用替换字符串（middle）显示

StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"

appendIfMissing(String str, CharSequence suffix, CharSequence... suffixes) 如果str不是以任何suffixes结尾，将字符串suffix拼接到字符串str后面

StringUtils.appendIfMissing(null, null) = nullStringUtils.appendIfMissing("abc", null) = "abc"StringUtils.appendIfMissing("", "xyz") = "xyz"StringUtils.appendIfMissing("abc", "xyz") = "abcxyz"StringUtils.appendIfMissing("abcxyz", "xyz") = "abcxyz"StringUtils.appendIfMissing("abcXYZ", "xyz") = "abcXYZxyz"

appendIfMissingIgnoreCase(String str, CharSequence suffix, CharSequence... suffixes) 同上 不区分大小写

capitalize(String str) 将字符串第一个字符大写并返回

center(String str, int size) 用空格字符填充使字符串str位于长度为size的大字符串中间

StringUtils.center(null, *)   = nullStringUtils.center("", 4)     = "    "StringUtils.center("ab", -1)  = "ab"StringUtils.center("ab", 4)   = " ab "StringUtils.center("abcd", 2) = "abcd"StringUtils.center("a", 4)    = " a  "

center(String str, int size, char padChar) 用指定字符填充使字符串str位于长度为size的大字符串中间

chomp(String str) 删除字符串末尾的一个换行符,返回一个新的字符串（换行符"n", "r", or "rn"）

StringUtils.chomp(null)          = nullStringUtils.chomp("")            = ""StringUtils.chomp("abc \r")      = "abc "StringUtils.chomp("abc\n")       = "abc"StringUtils.chomp("abc\r\n")     = "abc"StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"StringUtils.chomp("abc\n\r")     = "abc\n"StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"StringUtils.chomp("\r")          = ""StringUtils.chomp("\n")          = ""StringUtils.chomp("\r\n")        = ""

chop(String str) 删除字符串末尾的一个字符，返回一个新的字符串

StringUtils.chop(null)          = nullStringUtils.chop("")            = ""StringUtils.chop("abc \r")      = "abc "StringUtils.chop("abc\n")       = "abc"StringUtils.chop("abc\r\n")     = "abc"StringUtils.chop("abc")         = "ab"StringUtils.chop("abc\nabc")    = "abc\nab"StringUtils.chop("a")           = ""StringUtils.chop("\r")          = ""StringUtils.chop("\n")          = ""StringUtils.chop("\r\n")        = ""

compare(String str1, String str2) 比较两个字符串，返回一个int值

str1等于str2（或都为空）返回0str1小于str2返回小于0str1大于str2返回大于0StringUtils.compare(null, null)   = 0StringUtils.compare(null , "a")   < 0StringUtils.compare("a", null)    > 0StringUtils.compare("abc", "abc") = 0StringUtils.compare("a", "b")     < 0StringUtils.compare("b", "a")     > 0StringUtils.compare("a", "B")     > 0StringUtils.compare("ab", "abc")  < 0

contains(CharSequence seq, CharSequence searchSeq) 检查字符串中是否包含指定字符，返回boolean

StringUtils.contains(null, *)     = falseStringUtils.contains(*, null)     = falseStringUtils.contains("", "")      = trueStringUtils.contains("abc", "")   = trueStringUtils.contains("abc", "a")  = trueStringUtils.contains("abc", "z")  = false

containsAny(CharSequence cs, CharSequence... searchCharSequences) 检查字符串中是否包含任一字符，返回boolean

StringUtils.containsAny(null, *)            = falseStringUtils.containsAny("", *)              = falseStringUtils.containsAny(*, null)            = falseStringUtils.containsAny(*, [])              = falseStringUtils.containsAny("abcd", "ab", null) = trueStringUtils.containsAny("abcd", "ab", "cd") = trueStringUtils.containsAny("abc", "d", "abc")  = true

containsNone(CharSequence cs, String invalidChars) 检查字符串不包含指定字符，返回boolean

StringUtils.containsNone(null, *)       = trueStringUtils.containsNone(*, null)       = trueStringUtils.containsNone("", *)         = trueStringUtils.containsNone("ab", "")      = trueStringUtils.containsNone("abab", "xyz") = trueStringUtils.containsNone("ab1", "xyz")  = trueStringUtils.containsNone("abz", "xyz")  = false

containsOnly(CharSequence cs, String validChars) 检查字符串只包含特定的字符，返回boolean

StringUtils.containsOnly(null, *)       = falseStringUtils.containsOnly(*, null)       = falseStringUtils.containsOnly("", *)         = trueStringUtils.containsOnly("ab", "")      = falseStringUtils.containsOnly("abab", "abc") = trueStringUtils.containsOnly("ab1", "abc")  = falseStringUtils.containsOnly("abz", "abc")  = false

containsWhitespace(CharSequence seq) 检查字符串中是否包含空格字符，返回boolean

countMatches(CharSequence str, CharSequence sub) 检查字符串中出现指定字符的次数，返回一个int值

StringUtils.countMatches(null, *)       = 0StringUtils.countMatches("", *)         = 0StringUtils.countMatches("abba", null)  = 0StringUtils.countMatches("abba", "")    = 0StringUtils.countMatches("abba", "a")   = 2StringUtils.countMatches("abba", "ab")  = 1StringUtils.countMatches("abba", "xxx") = 0

defaultIfBlank(T str, T defaultStr) 如果字符串为null、空（""），或全是空格，将返回指定字符串，否则返回原值

StringUtils.defaultIfBlank(null, "NULL")  = "NULL"StringUtils.defaultIfBlank("", "NULL")    = "NULL"StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"StringUtils.defaultIfBlank("bat", "NULL") = "bat"StringUtils.defaultIfBlank("", null)      = null

defaultIfEmpty(T str, T defaultStr) 如果字符串为null、空（""），将返回指定字符串，否则返回原值

StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"StringUtils.defaultIfEmpty("", "NULL")    = "NULL"StringUtils.defaultIfEmpty(" ", "NULL")   = " "StringUtils.defaultIfEmpty("bat", "NULL") = "bat"StringUtils.defaultIfEmpty("", null)      = null

defaultString(String str) 如果字符串为null，将返回空的字符串（""），否则返回原值

StringUtils.defaultString(null)  = ""StringUtils.defaultString("")    = ""StringUtils.defaultString("bat") = "bat"

defaultString(String str, String defaultStr) 如果字符串为null，将返回指定字符，否则返回原值

StringUtils.defaultString(null, "NULL")  = "NULL"StringUtils.defaultString("", "NULL")    = ""StringUtils.defaultString("bat", "NULL") = "bat"

deleteWhitespace(String str) 删除字符串中的空格字符，并返回新的字符串

StringUtils.deleteWhitespace(null)         = nullStringUtils.deleteWhitespace("")           = ""StringUtils.deleteWhitespace("abc")        = "abc"StringUtils.deleteWhitespace("   ab  c  ") = "abc"

difference(String str1, String str2) 比较两个字符串差异，并返回差异的字符，返回第二个字符串的剩余部分，这意味着“ABC”和“AB”之间的区别是空字符串而不是“C”。

StringUtils.difference(null, null) = nullStringUtils.difference("", "") = ""StringUtils.difference("", "abc") = "abc"StringUtils.difference("abc", "") = ""StringUtils.difference("abc", "abc") = ""StringUtils.difference("abc", "ab") = ""StringUtils.difference("ab", "abxyz") = "xyz"StringUtils.difference("abcde", "abxyz") = "xyz"StringUtils.difference("abcde", "xyz") = "xyz"

endsWith(CharSequence str, CharSequence suffix) 检查字符串是否以指定字符结尾，返回一个boolean

StringUtils.endsWith(null, null)      = trueStringUtils.endsWith(null, "def")     = falseStringUtils.endsWith("abcdef", null)  = falseStringUtils.endsWith("abcdef", "def") = trueStringUtils.endsWith("ABCDEF", "def") = falseStringUtils.endsWith("ABCDEF", "cde") = falseStringUtils.endsWith("ABCDEF", "")    = true

endsWithAny(CharSequence sequence, CharSequence... searchStrings) 检查字符串是否以指定字符数组结尾，返回一个boolean

StringUtils.endsWithAny(null, null)      = falseStringUtils.endsWithAny(null, new String[] {"abc"})  = falseStringUtils.endsWithAny("abcxyz", null)     = falseStringUtils.endsWithAny("abcxyz", new String[] {""}) = trueStringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = trueStringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = trueStringUtils.endsWithAny("abcXYZ", "def", "XYZ") = trueStringUtils.endsWithAny("abcXYZ", "def", "xyz") = false

endsWithIgnoreCase(CharSequence str, CharSequence suffix) 检查字符串是否以指定字符（不区分大小写）结尾，返回一个boolean

StringUtils.endsWithIgnoreCase(null, null)      = trueStringUtils.endsWithIgnoreCase(null, "def")     = falseStringUtils.endsWithIgnoreCase("abcdef", null)  = falseStringUtils.endsWithIgnoreCase("abcdef", "def") = trueStringUtils.endsWithIgnoreCase("ABCDEF", "def") = trueStringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false

equals(CharSequence cs1, CharSequence cs2) 比较两个字符串是否相等，返回一个boolean

StringUtils.equals(null, null)   = trueStringUtils.equals(null, "abc")  = falseStringUtils.equals("abc", null)  = falseStringUtils.equals("abc", "abc") = trueStringUtils.equals("abc", "ABC") = false

equalsAnyIgnoreCase(CharSequence string, CharSequence... searchStrings) 比较两个字符串是否相等（不区分大小写），返回一个boolean

StringUtils.equalsIgnoreCase(null, null)   = trueStringUtils.equalsIgnoreCase(null, "abc")  = falseStringUtils.equalsIgnoreCase("abc", null)  = falseStringUtils.equalsIgnoreCase("abc", "abc") = trueStringUtils.equalsIgnoreCase("abc", "ABC") = true

equalsAny(CharSequence string, CharSequence... searchStrings) 比较字符串是否与指定字符串数组中某一值相等，返回一个boolean

StringUtils.equalsAny(null, (CharSequence[]) null) = falseStringUtils.equalsAny(null, null, null)    = trueStringUtils.equalsAny(null, "abc", "def")  = falseStringUtils.equalsAny("abc", null, "def")  = falseStringUtils.equalsAny("abc", "abc", "def") = trueStringUtils.equalsAny("abc", "ABC", "DEF") = false

equalsAnyIgnoreCase(CharSequence string, CharSequence... searchStrings) 比较字符串是否与指定字符串数组中某一值相等（不区分大小写），返回一个boolean

StringUtils.equalsAnyIgnoreCase(null, (CharSequence[]) null) = falseStringUtils.equalsAnyIgnoreCase(null, null, null)    = trueStringUtils.equalsAnyIgnoreCase(null, "abc", "def")  = falseStringUtils.equalsAnyIgnoreCase("abc", null, "def")  = falseStringUtils.equalsAnyIgnoreCase("abc", "abc", "def") = trueStringUtils.equalsAnyIgnoreCase("abc", "ABC", "DEF") = true

getCommonPrefix(String... strs) 获取字符串数组元素公共字符，返回string

StringUtils.getCommonPrefix(null) = ""StringUtils.getCommonPrefix(new String[] {}) = ""StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"StringUtils.getCommonPrefix(new String[] {null, null}) = ""StringUtils.getCommonPrefix(new String[] {"", ""}) = ""StringUtils.getCommonPrefix(new String[] {"", null}) = ""StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "

indexOf(CharSequence seq, CharSequence searchSeq) 检查指定字符在字符串中出现的位置，返回一个int值

StringUtils.indexOf(null, *)          = -1StringUtils.indexOf(*, null)          = -1StringUtils.indexOf("", "")           = 0StringUtils.indexOf("", *)            = -1 (except when * = "")StringUtils.indexOf("aabaabaa", "a")  = 0StringUtils.indexOf("aabaabaa", "b")  = 2StringUtils.indexOf("aabaabaa", "ab") = 1StringUtils.indexOf("aabaabaa", "")   = 0

indexOfIgnoreCase(CharSequence seq, CharSequence searchSeq) 检查指定字符在字符串中出现的位置（不区分大小写），返回一个int值

isAllBlank(CharSequence... css) 检查数组所有字符是否为null、empty、或全是空格字符，返回一个boolean

StringUtils.isAllBlank(null)             = trueStringUtils.isAllBlank(null, "foo")      = falseStringUtils.isAllBlank(null, null)       = trueStringUtils.isAllBlank("", "bar")        = falseStringUtils.isAllBlank("bob", "")        = falseStringUtils.isAllBlank("  bob  ", null)  = falseStringUtils.isAllBlank(" ", "bar")       = falseStringUtils.isAllBlank("foo", "bar")     = falseStringUtils.isAllBlank(new String[] {})  = true

isAllEmpty(CharSequence... css) 检查数组所有字符是否为null、empty，返回一个boolean

StringUtils.isAllEmpty(null)             = trueStringUtils.isAllEmpty(null, "")         = trueStringUtils.isAllEmpty(new String[] {})  = trueStringUtils.isAllEmpty(null, "foo")      = falseStringUtils.isAllEmpty("", "bar")        = falseStringUtils.isAllEmpty("bob", "")        = falseStringUtils.isAllEmpty("  bob  ", null)  = falseStringUtils.isAllEmpty(" ", "bar")       = falseStringUtils.isAllEmpty("foo", "bar")     = false

isAllLowerCase(CharSequence cs) 检查字符串中所有字符是否是小写，返回一个boolean

isAllUpperCase(CharSequence cs) 检查字符串中所有字符是否是大写，返回一个boolean

isAnyBlank(CharSequence... css) 检查数组中字符串是否有一个为null、empty或全是空格字符，返回一个boolean

StringUtils.isAnyBlank(null)             = trueStringUtils.isAnyBlank(null, "foo")      = trueStringUtils.isAnyBlank(null, null)       = trueStringUtils.isAnyBlank("", "bar")        = trueStringUtils.isAnyBlank("bob", "")        = trueStringUtils.isAnyBlank("  bob  ", null)  = trueStringUtils.isAnyBlank(" ", "bar")       = trueStringUtils.isAnyBlank(new String[] {})  = falseStringUtils.isAnyBlank(new String[]{""}) = trueStringUtils.isAnyBlank("foo", "bar")     = false

isAnyEmpty(CharSequence... css) 检查数组中字符串是否有一个为null、empty，返回一个boolean

StringUtils.isAnyEmpty(null)             = trueStringUtils.isAnyEmpty(null, "foo")      = trueStringUtils.isAnyEmpty("", "bar")        = trueStringUtils.isAnyEmpty("bob", "")        = trueStringUtils.isAnyEmpty("  bob  ", null)  = trueStringUtils.isAnyEmpty(" ", "bar")       = falseStringUtils.isAnyEmpty("foo", "bar")     = falseStringUtils.isAnyEmpty(new String[]{})   = falseStringUtils.isAnyEmpty(new String[]{""}) = true

isBlank(CharSequence cs) 检查字符串是否为null、empty或空格字符，返回一个boolean

StringUtils.isBlank(null)      = trueStringUtils.isBlank("")        = trueStringUtils.isBlank(" ")       = trueStringUtils.isBlank("bob")     = falseStringUtils.isBlank("  bob  ") = false

isEmpty(CharSequence cs) 检查字符串是否为null、empty，返回一个boolean

StringUtils.isEmpty(null)      = trueStringUtils.isEmpty("")        = trueStringUtils.isEmpty(" ")       = falseStringUtils.isEmpty("bob")     = falseStringUtils.isEmpty("  bob  ") = false

isNotBlank(CharSequence cs) 检查字符串是否不为null、empty或空格字符，返回一个boolean

isNotEmpty(CharSequence cs) 检查字符串是否不为null、empty，返回一个boolean

isNumeric(CharSequence cs) 检查字符串是否是数字，返回一个boolean

StringUtils.isNumeric(null)   = falseStringUtils.isNumeric("")     = falseStringUtils.isNumeric("  ")   = falseStringUtils.isNumeric("123")  = trueStringUtils.isNumeric("१२३")  = trueStringUtils.isNumeric("12 3") = falseStringUtils.isNumeric("ab2c") = falseStringUtils.isNumeric("12-3") = falseStringUtils.isNumeric("12.3") = falseStringUtils.isNumeric("-123") = falseStringUtils.isNumeric("+123") = false

isWhitespace(CharSequence cs) 检查字符串是否是空格字符，返回一个boolean

StringUtils.isWhitespace(null)   = falseStringUtils.isWhitespace("")     = trueStringUtils.isWhitespace("  ")   = trueStringUtils.isWhitespace("abc")  = falseStringUtils.isWhitespace("ab2c") = falseStringUtils.isWhitespace("ab-c") = false

join(byte[] array, char separator) 将字节数组转换成string，以指定字符分隔

StringUtils.join(null, *)               = nullStringUtils.join([], *)                 = ""StringUtils.join([null], *)             = ""StringUtils.join([1, 2, 3], ';')  = "1;2;3"StringUtils.join([1, 2, 3], null) = "123"

char、double、float、int、long、short、object、T同理

joinWith(String separator, Object... objects) 将多个元素已指定字符分隔拼接成String

StringUtils.joinWith(",", {"a", "b"})        = "a,b"StringUtils.joinWith(",", {"a", "b",""})     = "a,b,"StringUtils.joinWith(",", {"a", null, "b"})  = "a,,b"StringUtils.joinWith(null, {"a", "b"})       = "ab"

lastIndexOf(CharSequence seq, CharSequence searchSeq) 获取指定字符在字符串中的最后一个索引位置

StringUtils.lastIndexOf(null, *)          = -1StringUtils.lastIndexOf(*, null)          = -1StringUtils.lastIndexOf("", "")           = 0StringUtils.lastIndexOf("aabaabaa", "a")  = 7StringUtils.lastIndexOf("aabaabaa", "b")  = 5StringUtils.lastIndexOf("aabaabaa", "ab") = 4StringUtils.lastIndexOf("aabaabaa", "")   = 8

left(String str, int len) 返回从左边开始指定大小的字符串

StringUtils.left(null, *)    = nullStringUtils.left(*, -ve)     = ""StringUtils.left("", *)      = ""StringUtils.left("abc", 0)   = ""StringUtils.left("abc", 2)   = "ab"StringUtils.left("abc", 4)   = "abc"

right(String str, int len) 同上相反

length(CharSequence cs) 获取字符串大小，返回一个int

lowerCase(String str) 将字符串转换为小写，返回一个string

StringUtils.lowerCase(null)  = nullStringUtils.lowerCase("")    = ""StringUtils.lowerCase("aBc") = "abc"

upperCase(String str) 同上相反

mid(String str, int pos, int len) 获取字符串指定位置区间的字符，返回一个string

StringUtils.mid(null, *, *)    = nullStringUtils.mid(*, *, -ve)     = ""StringUtils.mid("", 0, *)      = ""StringUtils.mid("abc", 0, 2)   = "ab"StringUtils.mid("abc", 0, 4)   = "abc"StringUtils.mid("abc", 2, 4)   = "c"StringUtils.mid("abc", 4, 2)   = ""StringUtils.mid("abc", -2, 2)  = "ab"

overlay(String str, String overlay, int start, int end) 在字符串位置区间插入指定字符，返回一个string

StringUtils.overlay(null, *, *, *)            = nullStringUtils.overlay("", "abc", 0, 0)          = "abc"StringUtils.overlay("abcdef", null, 2, 4)     = "abef"StringUtils.overlay("abcdef", "", 2, 4)       = "abef"StringUtils.overlay("abcdef", "", 4, 2)       = "abef"StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"

prependIfMissing(String str, CharSequence prefix, CharSequence... prefixes) 在字符串最左边插入指定字符，如果已存在，将不插入，返回一个string

StringUtils.prependIfMissing(null, null) = nullStringUtils.prependIfMissing("abc", null) = "abc"StringUtils.prependIfMissing("", "xyz") = "xyz"StringUtils.prependIfMissing("abc", "xyz") = "xyzabc"StringUtils.prependIfMissing("xyzabc", "xyz") = "xyzabc"StringUtils.prependIfMissing("XYZabc", "xyz") = "xyzXYZabc"

prependIfMissingIgnoreCase(String str, CharSequence prefix, CharSequence... prefixes) 同上，只是不区分大小写

remove(String str, char remove) 删除字符串中指定字符，返回一个string

StringUtils.remove(null, *)       = nullStringUtils.remove("", *)         = ""StringUtils.remove("queued", 'u') = "qeed"StringUtils.remove("queued", 'z') = "queued"

removeIgnoreCase(String str, String remove) 同上，只是不区分大小写

removeAll(String text, String regex) 根据匹配规则删除所有字符，返回一个string

StringUtils.removeAll(null, *)      = nullStringUtils.removeAll("any", null)  = "any"StringUtils.removeAll("any", "")    = "any"StringUtils.removeAll("any", ".*")  = ""StringUtils.removeAll("any", ".+")  = ""StringUtils.removeAll("abc", ".?")  = ""StringUtils.removeAll("A<__>\n<__>B", "<.*>")      = "A\nB"StringUtils.removeAll("A<__>\n<__>B", "(?s)<.*>")  = "AB"StringUtils.removeAll("ABCabc123abc", "[a-z]")     = "ABC123"

removeEnd(String str, String remove) 删除字符串结尾指定字符，返回一个string

StringUtils.removeEnd(null, *)      = nullStringUtils.removeEnd("", *)        = ""StringUtils.removeEnd(*, null)      = *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.removeEnd("abc", "")    = "abc"

removeStart(String str, String remove) 同上相反

removeEndIgnoreCase(String str, String remove) 同上，只是不区分大小写

removeFirst(String text, String regex) 根据匹配规则删除第一次出现的字符，返回一个string

StringUtils.removeFirst(null, *)      = nullStringUtils.removeFirst("any", null)  = "any"StringUtils.removeFirst("any", "")    = "any"StringUtils.removeFirst("any", ".*")  = ""StringUtils.removeFirst("any", ".+")  = ""StringUtils.removeFirst("abc", ".?")  = "bc"StringUtils.removeFirst("A<__>\n<__>B", "<.*>")      = "A\n<__>B"StringUtils.removeFirst("A<__>\n<__>B", "(?s)<.*>")  = "AB"StringUtils.removeFirst("ABCabc123", "[a-z]")          = "ABCbc123"StringUtils.removeFirst("ABCabc123abc", "[a-z]+")      = "ABC123abc"

repeat(String str, int repeat) 将字符重复指定次数拼接成新的字符串，返回一个string

StringUtils.repeat(null, 2) = nullStringUtils.repeat("", 0)   = ""StringUtils.repeat("", 2)   = ""StringUtils.repeat("a", 3)  = "aaa"StringUtils.repeat("ab", 2) = "abab"StringUtils.repeat("a", -2) = ""

replace(String text, String searchString, String replacement) 用replacement替换字符串中的所有searchString，返回一个string

StringUtils.replace(null, *, *)        = nullStringUtils.replace("", *, *)          = ""StringUtils.replace("any", null, *)    = "any"StringUtils.replace("any", *, null)    = "any"StringUtils.replace("any", "", *)      = "any"StringUtils.replace("aba", "a", null)  = "aba"StringUtils.replace("aba", "a", "")    = "b"StringUtils.replace("aba", "a", "z")   = "zbz"

reverse(String str) 将字符串反转，返回一个string

StringUtils.reverse(null)  = nullStringUtils.reverse("")    = ""StringUtils.reverse("bat") = "tab"

reverseDelimited(String str, char separatorChar) 将字符串指定分隔符出的字符反转

StringUtils.reverseDelimited(null, *)      = null StringUtils.reverseDelimited("", *)        = "" StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c" StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"

split(String str, String separatorChars) 将字符串以指定字符分隔，返回数组

StringUtils.split(null, *)         = nullStringUtils.split("", *)           = []StringUtils.split("abc def", null) = ["abc", "def"]StringUtils.split("abc def", " ")  = ["abc", "def"]StringUtils.split("abc  def", " ") = ["abc", "def"]StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]

substring(String str, int start) 将字符串从指定位置区间截取，返回string

swapCase(String str) 将字符串大小写互转，返回一个string

StringUtils.swapCase(null)                 = nullStringUtils.swapCase("")                   = ""StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"

toEncodedString(byte[] bytes, Charset charset) 将字符串转为指定编码格式，返回一个string

trim(String str) 去除字符串空格

trimToEmpty(String str) 去除字符串空格，null转为empty，返回一个string

StringUtils.trimToEmpty(null)          = ""StringUtils.trimToEmpty("")            = ""StringUtils.trimToEmpty("     ")       = ""StringUtils.trimToEmpty("abc")         = "abc"StringUtils.trimToEmpty("    abc    ") = "abc"