Google Guava 实战之字符串处理篇

刺骨的言语ヽ痛彻心扉 2023-02-13 11:11 54阅读 0赞

<dependency>
         <groupId>com.google.guava</groupId>
         <artifactId>guava</artifactId>
         <version>27.0.1-jre</version>
     </dependency>

/**
             * 1、Joiner 连接器
             * 用分隔符把字符串序列连接起来也可能会遇上不必要的麻烦。如果字符串序列中含有null，那连接操作会更难，就可以使用Joiner
             * 如果既未指定也skipNulls()未useForNull(String)指定,使用null,会报NullPointerException
             *
             * skipNulls():就是跳过null
             * useForNull(String)：就是如果有null,则换成你给的默认值
             */
            Joiner joiner = Joiner.on(";").useForNull("我是null");
            String join = joiner.join("hello", null, "world", "guava");
            System.out.println("Joiner=============使用useForNull=========：" + join);
    
            Joiner joiner2 = Joiner.on(";").skipNulls();
            String join2 = joiner2.join("hello", null, "world", "guava");
            System.out.println("Joiner=============使用skipNulls========：" + join2);
    
            StringBuilder stringBuilder = new StringBuilder();
            Joiner joiner3 = Joiner.on(":").skipNulls();
            StringBuilder sb = joiner3.appendTo(stringBuilder, "hello", null, "world", "guava");
            System.out.println("Joiner.appendTo=============使用skipNulls========：" + sb);
    
            /**
             *  withKeyValueSeparator(char keyValueSeparator)
             *  withKeyValueSeparator 方法指定了键与值的分隔符，同时返回一个 MapJoiner 实例。
             *  Map里可以插入键或值为空指针的键值对，如果我们要拼接这种 Map，千万记得要用 useForNull对 MapJoiner做保护
             *  ps：不能使用skipNulls()跳过null，否者Exception in thread "main" java.lang.UnsupportedOperationException: can't use .skipNulls() with maps
             *  这里可以使用useForNull(string)对null值和null键进行处理
             */
            Map<String, Object> map = new HashMap<>();
            map.put("张三", 123);
            map.put("李四", 457);
            map.put("王五", 235);
            map.put("马六", 752);
            map.put("田七", null);
            map.put(null, 000);
            Joiner joiner4 = Joiner.on(":").useForNull("我是null");
            Joiner.MapJoiner mapJoiner = joiner4.withKeyValueSeparator("=>");
            String joinMap = mapJoiner.join(map);
            System.out.println("Joiner=============withKeyValueSeparator==========="+joinMap);

**控制台打印： **

Joiner=============使用useForNull=========：hello;我是null;world;guava
    Joiner=============使用skipNulls========：hello;world;guava
    Joiner.appendTo=============使用skipNulls========：hello:world:guava
    Joiner=============withKeyValueSeparator===========我是null=>0:李四=>457:张三=>123:马六=>752:王五=>235:田七=>我是null

package com.lucifer.utils;
    
    
    import com.google.common.base.CaseFormat;
    import com.google.common.base.CharMatcher;
    import com.google.common.base.Splitter;
    
    import java.util.List;
    
    /**
     * author: lucifer
     * date: 2020/5/28 13:37
     * description: TODO
     */
    public class test {
    
        public static void main(String[] args) {
    
            //Splitter.on(char):按单个字符拆分  Splitter.on(‘,’)
            Splitter splitter = Splitter.on(",");
            String str = "foo,bar,,   qux";
            String str1 = "hello,world!guava!!";
            String str2 = "fo??o??????bar?????qux????";
            String str3 = "abcd1234efg";
            String str4 = "ABCd1234Efg";
            String str5 = "ABCd1234./]?*@#$(*&Efg";
            String str6 = "ab34cd154ef567g";
            String str7 = "ab5yt5cd55e0fg55hi123jkl4mno65pq9x9yz7vtw";
            String str8 = "abcd11abcd22abcd33abcdaba";
            String str9 = "   a 2b 3c 44 de fh k  % %$ # ";
    
            //1.直接分割
            Iterable<String> split = splitter.split(str);
            System.out.println("1==============split:" + split);
            //2.trimResults():自动删除开头和结尾的空白 ，从每个返回字符串
            Iterable<String> split2 = splitter.trimResults().split(str);
            System.out.println("2==============split2:" + split2);
            //3.omitEmptyStrings():自动省略从结果空字符串
            Iterable<String> split3 = splitter.omitEmptyStrings().split(str);
            System.out.println("3==============split3:" + split3);
            //4、trimResults+omitEmptyStrings:去空格+去空字符串
            Iterable<String> split4 = splitter.omitEmptyStrings().trimResults().split(str);
            System.out.println("4==============split4:" + split4);
            //5、splitToList(string):将字符串分割，返回一个list
            //5.1
            List<String> list = splitter.splitToList(str);
            System.out.println("5.1=============" + list);
            //5.2
            List<String> list1 = splitter.omitEmptyStrings().trimResults().splitToList(str);
            System.out.println("5.2=============" + list1);
            //6、fixedLength：字符串按固定长度分割
    //        Splitter fixedLengthSplitter = splitter.omitEmptyStrings().trimResults().fixedLength(3);
    //        Iterable<String> fixedSplit = fixedLengthSplitter.split(str1);
            Iterable<String> fixedSplit = Splitter.fixedLength(3).omitEmptyStrings().trimResults().split(str);
            System.out.println("6==============fixedSplit:" + fixedSplit);
            //7.根据正则分割
            Splitter splitterPattern = Splitter.onPattern("\\?").omitEmptyStrings().trimResults();
            Iterable<String> split1 = splitterPattern.split(str2);
            System.out.println("7==============" + split1);
            //8.字符匹配器
            //8.1 CharMatcher.javaLetter() 匹配字母  (已废弃)
            String removeFrom = CharMatcher.javaLetter().removeFrom(str3);
            System.out.println("8.1==============CharMatcher.javaLetter():" + removeFrom);
            //8.2 CharMatcher.javaUpperCase() 匹配大写字母 (已废弃)
            CharMatcher charMatcher = CharMatcher.javaUpperCase();
            String upperCaseStr = charMatcher.removeFrom(str4);
            System.out.println("8.2===============upperCaseStr:" + upperCaseStr);
            //8.3 CharMatcher.javaUpperCase() 匹配大写字母 (已废弃)
            CharMatcher lowerCaseCharMatcher = CharMatcher.javaLowerCase();
            String lowerCaseStr = lowerCaseCharMatcher.removeFrom(str4);
            System.out.println("8.3===============lowerCaseStr:" + lowerCaseStr);
            //8.4 CharMatcher.digit() 匹配ASCII数字  (已废弃)
            //CharMatcher.digit().retainFrom(str) 只保留数字
            String retainFrom = CharMatcher.digit().retainFrom(str5);
            System.out.println("8.4===============retainFrom:" + retainFrom);
            //8.5 CharMatcher.javaDigit() 匹配UNICODE数字  (已废弃)
            //用*号替换所有数字
            String replaceFrom = CharMatcher.javaDigit().replaceFrom(str6, "*");
            System.out.println("8.5===============replaceFrom:" + replaceFrom);
            //8.6 CharMatcher.anyOf() 表明你想匹配的所有字符
            CharMatcher abcdCharMatcher = CharMatcher.anyOf("abcd");
            String abcdStr = abcdCharMatcher.removeFrom(str3);
            System.out.println("8.6======================" + abcdStr);
            //8.7 CharMatcher.is():表明你想匹配的一个确定的字符
            CharMatcher charMatcher1 = CharMatcher.is('a');
            String isaStr = charMatcher1.removeFrom(str3);
            System.out.println("8.7======================" + isaStr);
            //8.8 表明你想匹配的一个字符范围，例如：CharMatcher.inRange('a', 'z')
            CharMatcher inRange = CharMatcher.inRange('a', 'e');
            String inRangeStr = inRange.removeFrom(str7);
            System.out.println("8.8======================" + inRangeStr);
            //8.9去除所有空格
            String s = CharMatcher.breakingWhitespace().removeFrom(str9);
            System.out.println("8.9===============CharMatcher.breakingWhitespace():" + s);
            String s1 = CharMatcher.whitespace().removeFrom(str9);
            System.out.println("8.9===============CharMatcher.whitespace():" + s1);
            //9.collapseFrom 把每组连续的匹配字符替换为特定字符
            String s2 = CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-');
            System.out.println("9============collapseFrom==========" + s2);
            //10 matchesAllOf 测试是否字符序列中的所有字符都匹配
            boolean b = CharMatcher.anyOf("eko").matchesAllOf("bookkeeper");
            System.out.println("10.1========matchesAllOf============" + b);
            boolean b2 = CharMatcher.anyOf("eko").matchesAllOf("ekookoeek");
            System.out.println("10.2========matchesAllOf============" + b2);
            //11 trimFrom 移除字符序列的前导匹配字符和尾部匹配字符。
            String s3 = CharMatcher.anyOf("ab").trimFrom(str8);
            System.out.println("11===========trimFrom=========" + s3);
            //12 removeFrom(CharSequence)
            //从字符序列中移除所有匹配字符。
            String s4 = CharMatcher.anyOf("ab").removeFrom(str8);
            System.out.println("12===========removeFrom=========" + s4);
            //13 retainFrom(CharSequence)
            //在字符序列中保留匹配字符，移除其他字符。
            String s5 = CharMatcher.anyOf("ab").retainFrom(str8);
            System.out.println("13===========retainFrom=========" + s5);
            /* 14、
               字符串格式大小转换
                格式:                范例:
                LOWER_CAMEL	        lowerCamel
                LOWER_HYPHEN	    lower-hyphen
                LOWER_UNDERSCORE	lower_underscore
                UPPER_CAMEL	        UpperCamel
                UPPER_UNDERSCORE	UPPER_UNDERSCORE
             */
            String to = CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, "dAtE_DaTe");
            System.out.println(to);
            String to5 = CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, "dAtE_DaTe");
            System.out.println(to5);
            String to1 = CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_CAMEL, "dAtE_DaTe");
            System.out.println(to1);
            String to2 = CaseFormat.LOWER_HYPHEN.to(CaseFormat.LOWER_CAMEL, "dAtE_DaTe");
            System.out.println(to2);
            String to3 = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, "dAt_EDaTe");
            System.out.println(to3);
            String to4 = CaseFormat.UPPER_CAMEL.to(CaseFormat.LOWER_CAMEL, "dAtEDaTe");
            System.out.println(to4);
            //15 统计所匹配字符
            //次数
            int aCount = CharMatcher.is('a').countIn(str8);
            System.out.println(aCount);
            //第一次匹配到的下标
            int aIndex = CharMatcher.is('b').indexIn(str8);
            System.out.println(aIndex);
            //最后一次匹配到的下标
            int lastIndexIn = CharMatcher.is('b').lastIndexIn(str8);
            System.out.println(lastIndexIn);
        }
    }

**控制台打印： **

1==============split:[foo, bar, ,    qux]
    2==============split2:[foo, bar, , qux]
    3==============split3:[foo, bar,    qux]
    4==============split4:[foo, bar, qux]
    5.1=============[foo, bar, ,    qux]
    5.2=============[foo, bar, qux]
    6==============fixedSplit:[hel, lo,, wor, ld!, gua, va!, !]
    7==============[fo, o, bar, qux]
    8.1==============CharMatcher.javaLetter():1234
    8.2===============upperCaseStr:d1234fg
    8.3===============lowerCaseStr:ABC1234E
    8.4===============retainFrom:1234
    8.5===============replaceFrom:ab**cd***ef***g
    8.6======================1234efg
    8.7======================bcd1234efg
    8.8======================5yt5550fg55hi123jkl4mno65pq9x9yz7vtw
    8.9===============CharMatcher.breakingWhitespace():a2b3c44defhk%%$#
    8.9===============CharMatcher.whitespace():a2b3c44defhk%%$#
    9============collapseFrom==========b-p-r
    10.1========matchesAllOf============false
    10.2========matchesAllOf============true
    11===========trimFrom=========cd11abcd22abcd33abcd
    12===========removeFrom=========cd11cd22cd33cd
    13===========retainFrom=========abababababa
    dateDate
    DateDate
    dAtE_DaTe
    date_date
    datEdate
    dAtEDaTe
    6
    1
    23