驼峰和下划线命名转换-java完美版

待我称王封你为后i 2024-03-24 00:24 88阅读 0赞

附测试样例。  
上代码：

import org.junit.jupiter.api.Test;
    import java.util.*;
    import java.util.function.Function;
    import java.util.stream.Stream;
    
    public class StringTest {
        
        /**
         * 驼峰式命名法
         */
        public static String toCamelStyle(String input) {
        
            if (input == null) {
        
                return null;
            }
            if ("".equalsIgnoreCase(input)) {
        
                return input;
            }
            Pattern compile = Pattern.compile("^_*([^_].*[^_])_*$");
            Matcher matcher = compile.matcher(input);
            if (matcher.find()) {
        
                input = matcher.group(1);
            } else {
        
                // 如果只有下划线则返回 空字符串
                return "";
            }
            StringBuilder sb = new StringBuilder();
            char[] chars = input.toCharArray();
            for (int i = 0; i < chars.length; i++) {
        
                boolean isUnderline = '_' == chars[i];
                if (isUnderline) {
        
                    // 下划线的后一个字符转大写，丢弃下划线
                    chars[i + 1] = Character.toUpperCase(chars[i + 1]);
                } else {
        
                    if (i == 0) {
        
                        sb.append(Character.toLowerCase(chars[i]));
                    } else {
        
                        // (当前是大写 && ( (前一个是大写 && 后一个是大写) || (是最后一个字符 && 前一个是大写) ) )
                        if (Character.isUpperCase(chars[i]) &&
                                (
                                        (i < chars.length - 1 && Character.isUpperCase(chars[i - 1]) && (Character.isUpperCase(chars[i + 1])))
                                                ||
                                                (i == chars.length - 1 && Character.isUpperCase(chars[i - 1]))
                                )
                        ) {
        
                            sb.append(Character.toLowerCase(chars[i]));
                        } else {
        
                            sb.append(chars[i]);
                        }
                    }
                }
            }
            return sb.toString();
        }
    
        /**
         * 下划线式命名法
         */
        public static String toUnderlineStyle(String input) {
        
            if (input == null) {
        
                return null;
            }
            if ("".equalsIgnoreCase(input)) {
        
                return input;
            }
            Pattern compile = Pattern.compile("^_*([^_].*[^_])_*$");
            Matcher matcher = compile.matcher(input);
            if (matcher.find()) {
        
                input = matcher.group(1);
            } else {
        
                // 如果只有下划线则返回 空字符串
                return "";
            }
    
            StringBuilder sb = new StringBuilder();
            char[] chars = input.toCharArray();
            for (int i = 0; i < chars.length; i++) {
        
                boolean isUpper = Character.isUpperCase(chars[i]);
    
                // ( ( 非首个字符 && 当前是大写 && 前一个是小写 ) || ( 非首个字符 && 非最后一个字符 && 当前是大写 && 后一个是小写 ) )
                if ((i > 0 && isUpper && Character.isLowerCase(chars[i - 1])) || (i > 0 && i < chars.length - 1 && isUpper && Character.isLowerCase(chars[i + 1]))) {
        
                    // 前一个字符不是下划线
                    if (chars[i - 1] != '_') {
        
                        sb.append('_');
                    }
                }
                sb.append(Character.toLowerCase(chars[i]));
            }
            return sb.toString();
        }
        
    
        public void test(String[] arr, Function<String, String> func) {
        
            Arrays.stream(arr).forEach(s -> {
        
                System.out.printf("%s --> %s%n", s, func.apply(s));
            });
        }
    
        @Test
        public void testCases() {
        
            String str1 = "test_abc";
            String Str2 = "test_Abc";
            String Str3 = "Test_abc";
            String Str4 = "testAbc";
            String Str5 = "TestAbc";
            String Str6 = "testabc";
            String Str7 = "Testabc";
            String Str8 = "_test_abc";
            String Str9 = "test_abc_";
            String Str10 = "_Testabc";
            String Str11 = "TestABC";
            String Str12 = "TestABC";
            String Str13 = "TESTAbc";
            String Str14 = "TestAbcW";
    
            String Str31="_";
            String Str32="__";
            String[] testArr = Stream.of(str1, Str2, Str3, Str4, Str5, Str6, Str7, Str8, Str9, Str10,Str11,Str12,Str13,Str14,Str31,Str32).toArray(String[]::new);
    
            test(testArr, StrUtils::toCamelStyle);
            System.out.println("===================================");
            test(testArr, StrUtils::toUnderlineStyle);
        }
    }

测试结果：

test_abc --> testAbc
    test_Abc --> testAbc
    Test_abc --> testAbc
    testAbc --> testAbc
    TestAbc --> testAbc
    testabc --> testabc
    Testabc --> testabc
    _test_abc --> testAbc
    test_abc_ --> testAbc
    _Testabc --> testabc
    TestABC --> testAbc
    TestABC --> testAbc
    TESTAbc --> testAbc
    TestAbcW --> testAbcW
    _ --> 
    __ --> 
    ===================================
    test_abc --> test_abc
    test_Abc --> test_abc
    Test_abc --> test_abc
    testAbc --> test_abc
    TestAbc --> test_abc
    testabc --> testabc
    Testabc --> testabc
    _test_abc --> test_abc
    test_abc_ --> test_abc
    _Testabc --> testabc
    TestABC --> test_abc
    TestABC --> test_abc
    TESTAbc --> test_abc
    TestAbcW --> test_abc_w
    _ --> 
    __ -->