Guava：CharMatcher字符匹配器

简介

CharMatcher 提供了各种方法来处理各种 JAVA char 类型值。

类方法说明

官方文档：CharMatcher (Guava: Google Core Libraries for Java 27.0.1-jre API)

使用Demo

import com.google.common.base.CharMatcher;
import org.junit.Test;

/**
 * 字符匹配
 */
public class CharMatcherTest {

    /**
     * collapseFrom 配到的字符做替换
     */
    @Test
    public void testCollapseFrom() {
        //配到的字符做替换
        //匹配空白
        String input = "     Hello World        ";
        String result = CharMatcher.breakingWhitespace().collapseFrom(input, '*');
        System.out.println(result);//*Hello*World*
        //匹配指定字符
        String result1 = CharMatcher.is('l').collapseFrom(input, '*');
        System.out.println(result1);//     He*o Wor*d    注意：两边空格还在

        //匹配指定字符
        String result2 = CharMatcher.inRange('l','o').collapseFrom(input, '*');
        System.out.println(result2);//     He* W*r*d    注意：两边空格还在

        //trimAndCollapseFrom：先去掉两边空格再进行替换
        String result3 = CharMatcher.breakingWhitespace().trimAndCollapseFrom(input, '*');
        System.out.println(result3);//Hello*World
    }

    /**
     * 去除空格
     */
    @Test
    public void testTrim() {
        String str = "     Hello World     ";

        //trimFrom 去两边空格
        System.out.println(CharMatcher.breakingWhitespace().trimFrom(str));           // Hello World
        //trimLeadingFrom 左边去空格
        System.out.println(CharMatcher.breakingWhitespace().trimLeadingFrom(str));    // Hello World
        //trimTrailingFrom右边去空格
        System.out.println(CharMatcher.breakingWhitespace().trimTrailingFrom(str));   //      Hello World
        System.out.println(CharMatcher.breakingWhitespace().removeFrom(str));   //HelloWorld
    }

    /**
     * retainFrom 保留匹配到的字符
     */
    @Test
    public void testRetainFrom() {
        String str = "   Hi 123 Hello 456 World  ";
        System.out.println(CharMatcher.is('l').retainFrom(str));   //lll

        //匹配字母和数字
        CharMatcher matcher = CharMatcher.forPredicate(Character::isLetterOrDigit);//Hi123Hello456World
        System.out.println(matcher.retainFrom(str));

        //匹配小写
        CharMatcher matcher2 = CharMatcher.forPredicate(Character::isLowerCase);//ielloorld
        System.out.println(matcher2.retainFrom(str));
    }

    /**
     * removeFrom 删除所有匹配的字符
     */
    @Test
    public void testRemoveFrom() {
        System.out.println(CharMatcher.is('l').removeFrom("   Hi 123 Hello 456 World  "));   //   Hi 123 Heo 456 Word
    }

    /**
     * countIn 查找字符在字符串中的个数
     */
    @Test
    public void testCountIn() {
        System.out.println(CharMatcher.is('a').countIn("Hello World Sharing the Google Guava Used"));  // 3

        String input = "H*el.lo,}12";
        //匹配数子
        CharMatcher matcher = CharMatcher.forPredicate(Character::isDigit);
        System.out.println(matcher.countIn(input));     //2

        matcher = CharMatcher.inRange('a', 'l');
        System.out.println(matcher.countIn(input));     // 3
    }

    /**
     * indexIn 匹配到的第一个字符的index
     * lastIndexIn 匹配到的最后一个字符的index
     *
     * 下标从0开始 若不存在返回-1
     */
    @Test
    public void testIndexIn_lastIndexIn() {
        String input = "Hello World";
        CharMatcher matcher = CharMatcher.is('l');

        System.out.println(matcher.indexIn(input));//2
        System.out.println(matcher.indexIn(input, 10));//-1
        System.out.println(matcher.lastIndexIn(input));//9
    }

    //=======匹配===========//

    /**
     * is 匹配参数之内的所有字符
     * isNot 匹配参数之外的所有字符
     */
    @Test
    public void testIs_isNot(){
        String input = "a, c, z, 1, 2";
        System.out.println(CharMatcher.is(',').retainFrom(input));   // ,,,,
        System.out.println(CharMatcher.is(',').removeFrom(input));   // a c z 1 2

        System.out.println(CharMatcher.isNot(',').retainFrom(input));   // a c z 1 2
        System.out.println(CharMatcher.isNot(',').removeFrom(input));   // ,,,,
    }

    /**
     * 匹配java转义字符
     */
    @Test
    public void testJavaIsoControl(){
        String input = "ab\tcd\nef\bg";
        CharMatcher matcher = CharMatcher.javaIsoControl();
        System.out.println(matcher.removeFrom(input));  // abcdefg
    }

    /**
     * 两个 Matcher 同时匹配
     */
    @Test
    public void testDoubleMatcher() {
        CharMatcher matcher0 = CharMatcher.forPredicate(Character::isLetterOrDigit);
        CharMatcher matcher1 = CharMatcher.forPredicate(Character::isLowerCase);

        String result = matcher0.and(matcher1).retainFrom("H*el.lo,}12");
        System.out.println(result); // ell0
    }

    /**
     * matchesAllOf 判断sequence所有字符是否都被charMatcher匹配
     * matchesAnyOf 判断sequence中是否存在字符被charMatcher匹配
     * matchesNoneOf 判断sequence所有字符是否都没被charMatcher匹配
     */
    @Test
    public void test_matchesAllOf_matchesAnyOf_matchesNoneOf(){
        String input = "**e,l.lo,}12";

        CharMatcher matcher = CharMatcher.is(',');
        System.out.println(matcher.matchesAllOf(input));    // false

        matcher = CharMatcher.is(',');
        System.out.println(matcher.matchesAnyOf(input));    // true

        matcher = CharMatcher.is('?');
        System.out.println(matcher.matchesNoneOf(input));   // true
    }

    /**
     * 匹配任意字符
     */
    @Test
    public void testAny() {
        String input = "H*el.lo,}12";

        CharMatcher matcher = CharMatcher.any();
        String result = matcher.replaceFrom(input,"替换，");
        System.out.println(result); //替换，替换，替换，替换，替换，替换，替换，替换，替换，替换，替换，

        matcher = CharMatcher.anyOf("Hel");
        System.out.println(matcher.retainFrom(input)); // Hell
        System.out.println(matcher.removeFrom(input)); // *.o,}12
    }

    /**
     * 匹配 Ascii 常用的字符编码标准
     */
    @Test
    public void testAscii() {
        String input = "罗あH*el.lo,}12";

        CharMatcher matcher = CharMatcher.ascii();
        System.out.println(matcher.retainFrom(input));  // H*el.lo,}12
        System.out.println(matcher.removeFrom(input));  // 罗あ
    }

    /**
     * 取反
     * negate 返回与当前CharMatcher相反的CharMatcher
     */
    @Test
    public void testNegate(){
        String input = "あH*el.lo,}12";

        CharMatcher matcher = CharMatcher.ascii().negate();
        System.out.println(matcher.retainFrom(input));     //  あ
        System.out.println(matcher.removeFrom(input));     //  H*el.lo,}12
    }

    /**
     * none 不匹配任何字符,与any()相反
     * noneOf 不匹配CharSequence内的任意一个字符,与anyOf()相反
     */
    @Test
    public void testNone_noneOf(){
        String input = "H*el.lo,}12";
        CharMatcher matcher = CharMatcher.none();
        System.out.println(matcher.retainFrom(input));          // ""
        System.out.println(matcher.retainFrom(input).length()); // 0

        matcher = CharMatcher.noneOf("Hel");
        System.out.println(matcher.retainFrom(input));          // *.o,}12
        System.out.println(matcher.removeFrom(input));          // Hell
    }

    /**
     * forPredicate 初始化匹配器
     */
    public void testForPredicate() {
//        CharMatcher charMatcher = CharMatcher.forPredicate(new Predicate<Character>() {
//            @Override
//            public boolean apply(@Nullable Character input) {
//                return Character.isLetterOrDigit(input);
//            }
//        });

        // lambda 写法
        CharMatcher charMatcher = CharMatcher.forPredicate(input -> Character.isLetterOrDigit(input));

        String input = "H*el.lo,}12";
        System.out.println(charMatcher.retainFrom(input));  // Hello12

    }
}