org.springframework.util.StringUtils的使用

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;