Java實現字串轉為駝峰格式的方法詳解

package com.yt.common.util;
import com.yt.common.dto.NameCode;
import com.yt.exam.enums.ZyEnum;
 
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
/**
 * 字串轉為駝峰格式 構建工具類
 * @author LYY
 * @date 2022/07/06
 */
 
public class RegexUtils {
 
    private static Pattern UNDERLINE_PATTERN = Pattern.compile("_([a-z])");
 
 
    public static void main(String[] args) {
        List<NameCode> nameCode = ZyEnum.getfield();
        for (int i = 0; i <nameCode.size() ; i++) {
            System.out.println(underlineToHump(nameCode.get(i).getField()));
        }
    }
 
    public static String underlineToHump (String str){
        //正則匹配下劃線及後一個字元，刪除下劃線並將匹配的字元轉成大寫
        Matcher matcher = UNDERLINE_PATTERN.matcher(str);
        StringBuffer sb = new StringBuffer(str);
        if (matcher.find()) {
            sb = new StringBuffer();
            //將當前匹配的子串替換成指定字串，並且將替換後的子串及之前到上次匹配的子串之後的字串新增到StringBuffer物件中
            //正則之前的字元和被替換的字元
            matcher.appendReplacement(sb, matcher.group(1).toUpperCase());
            //把之後的字串也新增到StringBuffer物件中
            matcher.appendTail(sb);
        } else {
            //去除除字母之外的前面帶的下劃線
            return sb.toString().replaceAll("_", "");
        }
        return underlineToHump(sb.toString());
    }
 
 
}

package yang.demo.justwrite;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @Description: 變數名轉換
 * @Class: VariableNameConversion
 * @Author: Yiang37
 * @Date: 2020/11/3 15:23
 * @Version: 1.0
 */
public class VariableNameConversion {

    private static Pattern humpPattern = Pattern.compile("[A-Z]");

    public static void main(String[] args) {

        System.out.println(lowerLineToHump("NAME_AND_addREsS"));
        System.out.println(capitalizeTheFirstLetter("nAMe"));
        System.out.println(humpToLowerLine("nameAndAddress"));

    }

    /**
     * @Description: 下劃線格式 -> 駝峰  大小寫均可
     * <p>
     * NAME_AND_ADDRESS -> nameAndAddress
     * @Author: Yiang37
     * @Date: 2020/11/03 15:26:02
     * @Version: 1.0
     * @method: lowerLineAndUppercaseToHump()
     * @param: [Big_]
     * @return: java.lang.String
     */
    public static String lowerLineToHump(String lowerLineAndUppercaseStr) {
        //拆分成陣列
        String[] eachStr = lowerLineAndUppercaseStr.split("_");
        StringBuilder resStr = new StringBuilder();
        String firstStr = "";
        String tempStr = "";
        for (int i = 0; i < eachStr.length; i++) {
            //第一個陣列全部小寫
            if (i == 0) {
                firstStr = eachStr[0].toLowerCase();
                resStr.append(firstStr);
            } else {
                //以後的陣列首字母大寫
                tempStr = capitalizeTheFirstLetter(eachStr[i]);
                resStr.append(tempStr);
            }
        }

        return resStr.toString();
    }

    /**
     * @Description: 任意字串 -> 首字母大寫
     * NAME -> Name
     * name -> Name
     * NaMe -> Name
     * @Author: Yiang37
     * @Date: 2020/11/03 16:50:16
     * @Version: 1.0
     * @method: capitalizeTheFirstLetter()
     * @param: [str]
     * @return: java.lang.String
     */
    public static String capitalizeTheFirstLetter(String str) {
        char firstChar = str.toUpperCase().charAt(0);
        String nextStr = str.toLowerCase().substring(1);
        return firstChar + nextStr;
    }

    /**
     * @Description: 駝峰 -> 下劃線格式 預設小寫,存在第二個形參且為true時大寫.
     * @Author: Yiang37
     * @Date: 2020/11/03 17:10:25
     * @Version: 1.0
     * @method: humpToLowerLine()
     * @param: [humpStr, UppercaseZeroAndLowercaseOne]
     * @return: java.lang.String
     */
    public static String humpToLowerLine(String humpStr, boolean ... defaultUppercaseAndTrueLowercase) {
        Matcher matcher = humpPattern.matcher(humpStr);
        StringBuffer sb = new StringBuffer();
        while (matcher.find()) {
            matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());
        }
        matcher.appendTail(sb);

        //如果第二個形參為true 轉為大寫
        if (defaultUppercaseAndTrueLowercase.length>=1 && defaultUppercaseAndTrueLowercase[0]){
            return sb.toString().toUpperCase();
        }
        return sb.toString();
    }

}