Google Guava 实战之字符串处理篇

 <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//5.1List<String> list = splitter.splitToList(str);System.out.println("5.1=============" + list);//5.2List<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	        lowerCamelLOWER_HYPHEN	    lower-hyphenLOWER_UNDERSCORE	lower_underscoreUPPER_CAMEL	        UpperCamelUPPER_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
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