我们经常会对字符串进行操作，spring已经实现了常用的处理功能。我们可以使用org.springframework.util.StringUtils 工具类帮我们处理字符串。
工具类整理如下：
? StringUtils.hasLength(null) = false
? StringUtils.hasLength("") = false
? StringUtils.hasLength(" ") = true
? StringUtils.hasLength("Hello") = true
?
?? StringUtils.hasText(null) = false
?? StringUtils.hasText("") = false
?? StringUtils.hasText(" ") = false
?? StringUtils.hasText("12345") = true
?? StringUtils.hasText(" 12345 ") = true
?//是否包含空白字符?
?StringUtils.containsWhitespace(null)=false
?StringUtils.containsWhitespace("")=false
?StringUtils.containsWhitespace("a")=false
?StringUtils.containsWhitespace("abc")=false
?StringUtils.containsWhitespace("abc")=false
?StringUtils.containsWhitespace(" ")=true
?StringUtils.containsWhitespace(" a")=true
?StringUtils.containsWhitespace("abc ")=true
?StringUtils.containsWhitespace("a b")=true
?StringUtils.containsWhitespace("a? b")

?StringUtils.trimWhitespace(null)=null;
?StringUtils.trimWhitespace("")="";
?StringUtils.trimWhitespace(" ")="";
?StringUtils.trimWhitespace("\t")="";
?StringUtils.trimWhitespace(" a")="a";
?StringUtils.trimWhitespace("a ")="a";
?StringUtils.trimWhitespace(" a ")="a";
?StringUtils.trimWhitespace(" a b ")="a b";

?StringUtils.trimLeadingWhitespace(null)=null;
?StringUtils.trimLeadingWhitespace("")="";
?StringUtils.trimLeadingWhitespace(" ")="";
?StringUtils.trimLeadingWhitespace("\t")="";
?StringUtils.trimLeadingWhitespace(" a")="a";
?StringUtils.trimLeadingWhitespace("a ")="a ";
?StringUtils.trimLeadingWhitespace(" a ")="a ";
?StringUtils.trimLeadingWhitespace(" a b ")="a b "
?StringUtils.trimLeadingWhitespace(" a b? c ")="a b? c "

?StringUtils.trimTrailingWhitespace(null)=null;
?StringUtils.trimTrailingWhitespace(" ")="";
?StringUtils.trimTrailingWhitespace("\t")="";
?StringUtils.trimTrailingWhitespace("a ")="a";
?StringUtils.trimTrailingWhitespace(" a")=" a";
?StringUtils.trimTrailingWhitespace(" a ")=" a";
?StringUtils.trimTrailingWhitespace(" a b ")=" a b";
?StringUtils.trimTrailingWhitespace(" a b? c ")=" a b? c";

?StringUtils.trimAllWhitespace("")="";
?StringUtils.trimAllWhitespace(" ")="";
?StringUtils.trimAllWhitespace("\t")="";
?StringUtils.trimAllWhitespace(" a")="a";
?StringUtils.trimAllWhitespace("a ")="a";
?StringUtils.trimAllWhitespace(" a ")="a";
?StringUtils.trimAllWhitespace(" a b ")="ab";
?StringUtils.trimAllWhitespace(" a b? c "="abc";
?//统计一个子字符串在字符串出现的次数?
?StringUtils.countOccurrencesOf(null, null) == 0;
?StringUtils.countOccurrencesOf("s", null) == 0;
?StringUtils.countOccurrencesOf(null, "s") == 0;
?StringUtils.countOccurrencesOf("erowoiueoiur", "WERWER") == 0;
?StringUtils.countOccurrencesOf("erowoiueoiur", "x")=0;
?StringUtils.countOccurrencesOf("erowoiueoiur", " ") == 0;
?StringUtils.countOccurrencesOf("erowoiueoiur", "") == 0;
?StringUtils.countOccurrencesOf("erowoiueoiur", "e") == 2;
?StringUtils.countOccurrencesOf("erowoiueoiur", "oi") == 2;
?StringUtils.countOccurrencesOf("erowoiueoiur", "oiu") == 2;
?StringUtils.countOccurrencesOf("erowoiueoiur", "oiur") == 1;
?StringUtils.countOccurrencesOf("erowoiueoiur", "r") == 2;

?//字符串替换
?String inString = "a6AazAaa77abaa";
?String oldPattern = "aa";
?String newPattern = "foo";
?// Simple replace
?String s = StringUtils.replace(inString, oldPattern, newPattern);
?s.equals("a6AazAfoo77abfoo")=true;

?// Non match: no change
?s = StringUtils.replace(inString, "qwoeiruqopwieurpoqwieur", newPattern);
?s.equals(inString)=true
?s = StringUtils.replace(inString, oldPattern, null);
?s.equals(inString)=true

?// Null old pattern: should ignore
?s = StringUtils.replace(inString, null, newPattern);
??????? s.equals(inString)=true
?//删除字符串

?String inString = "The quick brown fox jumped over the lazy dog";
?String noThe = StringUtils.delete(inString, "the");
?noThe.equals("The quick brown fox jumped over? lazy dog")=true;
?String nohe = StringUtils.delete(inString, "he");
?nohe.equals("T quick brown fox jumped over t lazy dog")=true;
?String nosp = StringUtils.delete(inString, " ");
?nosp.equals("Thequickbrownfoxjumpedoverthelazydog")=true;
?String killEnd = StringUtils.delete(inString, "dog");
?killEnd.equals("The quick brown fox jumped over the lazy ")=true;
?String mismatch = StringUtils.delete(inString, "dxxcxcxog");
? mismatch.equals(inString)=true;

?//删除任何字符
?//源代码如下
?//char c = inString.charAt(i);
?//如果不存在 c 值，则返回 -1
?//if (charsToDelete.indexOf(c) == -1) {
?//out.append(c);
?//}

?String inString = "Able was I ere I saw Elba";

?String res = StringUtils.deleteAny(inString, "I");
??????? res.equals("Able was? ere? saw Elba")=true;
?res = StringUtils.deleteAny(inString, "AeEba!");
?res.equals("l ws I r I sw l")=true;
?String mismatch = StringUtils.deleteAny(inString, "#@$#$^");
?mismatch.equals(inString)=true;

?//源代码如下 return (str != null ? "'" + str + "'" : null);
?assertEquals("'myString'", StringUtils.quote("myString"));
?assertEquals("''", StringUtils.quote(""));
?assertNull(StringUtils.quote(null));
?//将第一个字符改大写
?StringUtils.capitalize(Str)
?//将第一个个字符改小写
?StringUtils.uncapitalize(str)

?//mypath/myfile.txt" -> "myfile.txt
?//获取字符串文件名和扩展名
?StringUtils.getFilename("myfile").equals("myfile")=true;
?StringUtils.getFilename("mypath/myfile".equals("myfile")=true;
?StringUtils.getFilename("mypath/myfile".equals("myfile")=true;
?StringUtils.getFilename("myfile.txt").equals("myfile.txt")=true;
?StringUtils.getFilename("mypath/myfile.txt").equals("myfile.txt")=true;
?//获取字符串扩展名,以.分隔
?StringUtils.getFilenameExtension("myfile")=null;
?StringUtils.getFilenameExtension("myPath/myfile")=null;
?StringUtils.getFilenameExtension("myfile.").equals("")=true;
?StringUtils.getFilenameExtension("myPath/myfile.").equals("")=true;
?StringUtils.StringUtils.getFilenameExtension("myfile.txt").equals("txt")=true;
?StringUtils.getFilenameExtension("mypath/myfile.txt").equals("txt")=true;

?//舍去文件名扩展名
?StringUtils.stripFilenameExtension(null)=true;
?StringUtils.stripFilenameExtension("").equals("")=true;
?StringUtils.stripFilenameExtension("myfile").equals("myfile")=true;
?StringUtils.stripFilenameExtension("mypath/myfile").equals("mypath/myfile")=true;
?StringUtils.stripFilenameExtension("myfile.").equals("myfile")=true;
?StringUtils.stripFilenameExtension("mypath/myfile.").equals("mypath/myfile")=true;
?StringUtils.stripFilenameExtension("mypath/myfile.").equals("mypath/myfile")=true;
?StringUtils.stripFilenameExtension("myfile.txt").equals("myfile")=true;
?StringUtils.stripFilenameExtension("mypath/myfile.txt").equals("mypath/myfile")=true;