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;