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;