org.apache.commons.lang.StringUtil 常用方法使用例子

1.空字符串检查
使用函数: StringUtils.isBlank(testString)
函数介绍: 当testString为空,长度为零或者仅由空白字符(whitespace)组成时,返回True;否则返回False
例程:

String test = "";
String test2 = "\n\n\t";
String test3 = null;
String test4 = "Test";
System.out.println( "test blank? " + StringUtils.isBlank( test ) );
System.out.println( "test2 blank? " + StringUtils.isBlank( test2 ) );
System.out.println( "test3 blank? " + StringUtils.isBlank( test3 ) );
System.out.println( "test4 blank? " + StringUtils.isBlank( test4 ) );

    String test = "";
    String test2 = "\n\n\t";
    String test3 = null;
    String test4 = "Test"; 
    System.out.println( "test blank? " + StringUtils.isBlank( test ) );
    System.out.println( "test2 blank? " + StringUtils.isBlank( test2 ) );
    System.out.println( "test3 blank? " + StringUtils.isBlank( test3 ) );
    System.out.println( "test4 blank? " + StringUtils.isBlank( test4 ) );

输出如下:
test blank? true
test2 blank? true
test3 blank? true
test4 blank? False
函数StringUtils.isNotBlank(testString)的功能与StringUtils.isBlank(testString)相反.

2.清除空白字符
使用函数: StringUtils.trimToNull(testString)
函数介绍:清除掉testString首尾的空白字符,如果仅testString全由空白字符
(whitespace)组成则返回null
例程:

String test1 = "\t";
String test2 = " A Test ";
String test3 = null;

System.out.println( "test1 trimToNull: " + StringUtils.trimToNull( test1 ) );
System.out.println( "test2 trimToNull: " + StringUtils.trimToNull( test2 ) );
System.out.println( "test3 trimToNull: " + StringUtils.trimToNull( test3 ) );

    String test1 = "\t";
    String test2 = " A Test ";
    String test3 = null;

    System.out.println( "test1 trimToNull: " + StringUtils.trimToNull( test1 ) );
    System.out.println( "test2 trimToNull: " + StringUtils.trimToNull( test2 ) );
    System.out.println( "test3 trimToNull: " + StringUtils.trimToNull( test3 ) );

输出如下:
test1 trimToNull: null
test2 trimToNull: A Test
test3 trimToNull: null

注意：函数StringUtils.trim(testString)与
StringUtils.trimToNull(testString)功能类似，但testString由空白字符
(whitespace)组成时返回零长度字符串。

3.取得字符串的缩写
使用函数: StringUtils.abbreviate(testString,width)和StringUtils.abbreviate(testString,offset，width)
函数介绍:在给定的width内取得testString的缩写,当testString的长度小于width则返回原字符串.
例程:

String test = "This is a test of the abbreviation.";
String test2 = "Test";

System.out.println( StringUtils.abbreviate( test, 15 ) );
System.out.println( StringUtils.abbreviate( test, 5,15 ) );
System.out.println( StringUtils.abbreviate( test2, 10 ) );

    String test = "This is a test of the abbreviation.";
    String test2 = "Test";

    System.out.println( StringUtils.abbreviate( test, 15 ) );
    System.out.println( StringUtils.abbreviate( test, 5,15 ) );
    System.out.println( StringUtils.abbreviate( test2, 10 ) );

输出如下:
This is a te...
...is a test...
Test

4.劈分字符串
使用函数: StringUtils.split(testString,splitChars,arrayLength)
函数介绍:splitChars中可以包含一系列的字符串来劈分testString,并可以设定得
到数组的长度.注意设定长度arrayLength和劈分字符串间有抵触关系,建议一般情况下
不要设定长度.
例程:

String input = "A b,c.d|e";
String input2 = "Pharmacy, basketball funky";

String[] array1 = StringUtils.split( input, " ,.|");
String[] array2 = StringUtils.split( input2, " ,", 2 );

System.out.println( ArrayUtils.toString( array1 ) );
System.out.println( ArrayUtils.toString( array2 ) );

    String input = "A b,c.d|e";
    String input2 = "Pharmacy, basketball funky";
   
    String[] array1 = StringUtils.split( input, " ,.|");
    String[] array2 = StringUtils.split( input2, " ,", 2 );

    System.out.println( ArrayUtils.toString( array1 ) );
    System.out.println( ArrayUtils.toString( array2 ) );

输出如下:
{A,b,c,d,e}
{Pharmacy,basketball funky}

5.查找嵌套字符串
使用函数:StringUtils.substringBetween(testString,header,tail)
函数介绍：在testString中取得header和tail之间的字符串。不存在则返回空
例程：

String htmlContent = "ABC1234ABC4567";
System.out.println(StringUtils.substringBetween(htmlContent, "1234", "4567"));
System.out.println(StringUtils.substringBetween(htmlContent, "12345", "4567"));

    String htmlContent = "ABC1234ABC4567";
    System.out.println(StringUtils.substringBetween(htmlContent, "1234", "4567"));
    System.out.println(StringUtils.substringBetween(htmlContent, "12345", "4567"));

输出如下：
    ABC
    null


6.去除尾部换行符
使用函数:StringUtils.chomp(testString)
函数介绍:去除testString尾部的换行符
例程:

String input = "Hello\n";
System.out.println( StringUtils.chomp( input ));
String input2 = "Another test\r\n";
System.out.println( StringUtils.chomp( input2 ));

    String input = "Hello\n";
    System.out.println( StringUtils.chomp( input ));
    String input2 = "Another test\r\n";
    System.out.println( StringUtils.chomp( input2 ));

输出如下:
    Hello
    Another test


7.重复字符串
使用函数:StringUtils.repeat(repeatString,count)
函数介绍:得到将repeatString重复count次后的字符串
例程:

System.out.println( StringUtils.repeat( "*", 10));
System.out.println( StringUtils.repeat( "China ", 5));

    System.out.println( StringUtils.repeat( "*", 10));
    System.out.println( StringUtils.repeat( "China ", 5));

输出如下:
    **********
    China China China China China

其他函数:StringUtils.center( testString, count,repeatString );
函数介绍:把testString插入将repeatString重复多次后的字符串中间,得到字符串
的总长为count
例程:

System.out.println( StringUtils.center( "China", 11,"*"));

    System.out.println( StringUtils.center( "China", 11,"*"));

输出如下:
    ***China***


8.颠倒字符串
使用函数:StringUtils.reverse(testString)
函数介绍:得到testString中字符颠倒后的字符串
例程:

System.out.println( StringUtils.reverse("ABCDE"));

    System.out.println( StringUtils.reverse("ABCDE"));

输出如下:
    EDCBA

9.判断字符串内容的类型
函数介绍:
StringUtils.isNumeric( testString ) :如果testString全由数字组成返回True
StringUtils.isAlpha( testString ) :如果testString全由字母组成返回True
StringUtils.isAlphanumeric( testString ) :如果testString全由数字或数字组
成返回True
StringUtils.isAlphaspace( testString ) :如果testString全由字母或空格组
成返回True

例程:

String state = "Virginia";
System.out.println( "Is state number? " + StringUtils.isNumeric(state ) );
System.out.println( "Is state alpha? " + StringUtils.isAlpha( state ));
System.out.println( "Is state alphanumeric? " +StringUtils.isAlphanumeric( state ) );
System.out.println( "Is state alphaspace? " + StringUtils.isAlphaSpace( state ) );

    String state = "Virginia";
    System.out.println( "Is state number? " + StringUtils.isNumeric(state ) );
    System.out.println( "Is state alpha? " + StringUtils.isAlpha( state ));
    System.out.println( "Is state alphanumeric? " +StringUtils.isAlphanumeric( state ) );
    System.out.println( "Is state alphaspace? " + StringUtils.isAlphaSpace( state ) );

输出如下:
    Is state number? false
    Is state alpha? true
    Is state alphanumeric? true
    Is state alphaspace? true

10.取得某字符串在另一字符串中出现的次数
使用函数:StringUtils.countMatches(testString,seqString)
函数介绍:取得seqString在testString中出现的次数,未发现则返回零
例程:

System.out.println(StringUtils.countMatches( "Chinese People", "e"));

    System.out.println(StringUtils.countMatches( "Chinese People", "e"));

输出:
    4

11.部分截取字符串
使用函数:
StringUtils.substringBetween(testString,fromString,toString ):取得两字符
之间的字符串
StringUtils.substringAfter( ):取得指定字符串后的字符串
StringUtils.substringBefore( )：取得指定字符串之前的字符串
StringUtils.substringBeforeLast( )：取得最后一个指定字符串之前的字符串
StringUtils.substringAfterLast( )：取得最后一个指定字符串之后的字符串

函数介绍：上面应该都讲明白了吧。
例程：

String formatted = " 25 * (30,40) [50,60] | 30";
System.out.print("N0: " + StringUtils.substringBeforeLast( formatted, "*" ) );
System.out.print(", N1: " + StringUtils.substringBetween( formatted, "(", "," ) );
System.out.print(", N2: " + StringUtils.substringBetween( formatted, ",", ")" ) );
System.out.print(", N3: " + StringUtils.substringBetween( formatted, "[", "," ) );
System.out.print(", N4: " + StringUtils.substringBetween( formatted, ",", "]" ) );
System.out.print(", N5: " + StringUtils.substringAfterLast( formatted, "|" ) );

    String formatted = " 25 * (30,40) [50,60] | 30";
    System.out.print("N0: " + StringUtils.substringBeforeLast( formatted, "*" ) );
    System.out.print(", N1: " + StringUtils.substringBetween( formatted, "(", "," ) );
    System.out.print(", N2: " + StringUtils.substringBetween( formatted, ",", ")" ) );
    System.out.print(", N3: " + StringUtils.substringBetween( formatted, "[", "," ) );
    System.out.print(", N4: " + StringUtils.substringBetween( formatted, ",", "]" ) );
    System.out.print(", N5: " + StringUtils.substringAfterLast( formatted, "|" ) );

输出如下：
    N0: 25 , N1: 30, N2: 40, N3: 50, N4: 40) [50,60, N5: 30