Spring的工具类StringUtils使用

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;