java：下划线转小驼峰
import com.google.common.collect.Lists;
import com.xiaoxu.crawler.excp.CrawlerForJException;
import org.apache.commons.lang3.ArrayUtils;
import org.springframework.util.CollectionUtils;
import org.springframework.util.StringUtils;
import java.text.MessageFormat;
import java.util.List;
/**
* @author xiaoxu
* @date 2022-11-19 21:52
* crawlerJ:
*/
public class StrUtils {
private static final String underLineMark = "_";
private static final String kebabMark = "-";
private static final String EMPTY_STRING = "";
public static boolean equals(String a, String b){
if(null == a){
return null == b;
}
return a.equals(b);
}
public static int getMatchCount(String str, String subStr){
if(!StringUtils.hasLength(str) || !StringUtils.hasLength(subStr)){
ExcpUtils.throwExp(
MessageFormat.format(
"getMatchCount's str and subStr should not be null or empty:{0},{1}.",
str, subStr));
}
return StringUtils.countOccurrencesOf(str, subStr);
}
public static String nonEmptyStr(String value){
if(!StringUtils.hasLength(value)){
return EMPTY_STRING;
}
return value;
}
/**
* @param name 下划线
* @return 小驼峰
*/
public static String underlineTransferSmallHump(String name){
return symbolTransferSmallCamel(name, underLineMark.toCharArray()[0]);
}
@SuppressWarnings("all")
public static String symbolTransferSmallCamel(String name, Character symbol){
if(!StringUtils.hasLength(name)) {
return EMPTY_STRING;
}
if(null == symbol){
throw new CrawlerForJException("symbol access empty");
}
if(nonEmptyContains(name, symbol.toString())){
CharSequence cs = name;
int i = 0, csLen = cs.length();
StringBuilder sbd = new StringBuilder(csLen);
boolean isUpper = false;
for(; i < csLen; ++ i){
char c;
if(i == 0 && Character.isUpperCase(c = cs.charAt(i))){
sbd.append(Character.toLowerCase(c));
continue;
}
c = cs.charAt(i);
if(c == symbol){
isUpper = true;
}else if(isUpper){
if(sbd.length() == 0){
sbd.append(Character.toLowerCase(c));
}else{
sbd.append(Character.toUpperCase(c));
}
isUpper = false;
}else {
sbd.append(c);
}
}
return sbd.toString();
}else{
int strLen;
return (strLen = name.length()) > 1
? name.substring(0, 1).toLowerCase() + name.substring(1, strLen)
: name.toLowerCase();
}
}
public static boolean nonEmptyContains(String str1, String str2){
// if str2 "", str1 "XXX", must true, so here return false
if(!StringUtils.hasLength(str1) || !StringUtils.hasLength(str2)) return false;
return str1.contains(str2);
}
public static String simpleHumpTransferUnderline(String name){
return symbolTransfer(name, underLineMark);
}
public static String simpleHumpTransferKebab(String name){
return symbolTransfer(name, kebabMark);
}
@SuppressWarnings("all")
private static String symbolTransfer(String name, CharSequence symbol) {
if(!StringUtils.hasLength(name)) {
return EMPTY_STRING;
}
ExcpUtils.throwExpIfFalse(StringUtils.hasLength(symbol),
"symbol access empty");
StringBuilder sbd = new StringBuilder();
CharSequence cs = name;
int i = 0, csLen;
for(; i < (csLen = cs.length()); i++){
char c = cs.charAt(i);
if(Character.isUpperCase(c)){
Character pre = i > 0 ? cs.charAt(i - 1) : null;
if(null != pre){
sbd.append(symbol);
}
c = Character.toLowerCase(c);
}
sbd.append(c);
}
return sbd.toString();
}
/**
* @param name 小驼峰命名Str
* @return 下划线
*/
@SuppressWarnings("all")
public static String humpTransferUnderline(String name){
// null or empty throw exp
ExcpUtils.throwExpIfFalse(StringUtils.hasLength(name),
"when hump transfer to underline, name should not be empty.");
CharSequence cs = name;
List<CharSequence> charSequenceList = Lists.newArrayList();
int temI = 0, i = 0, csLen = 0;
for (; i < (csLen = cs.length()); i++) {
char c = cs.charAt(i);
if(Character.isUpperCase(c)){
CharSequence csq = cs.subSequence(temI, i);
if(csq.length() > 0){
addCharSequence(charSequenceList, csq);
temI = i;
}
}
}
CharSequence lastSequence = cs.subSequence(temI, csLen);
if(lastSequence.length() > 0){
addCharSequence(charSequenceList, lastSequence);
}
// actual could not execute this
if(CollectionUtils.isEmpty(charSequenceList)) return EMPTY_STRING;
return String.join(underLineMark, charSequenceList);
}
private static void addCharSequence(List<CharSequence> charSequenceList,
CharSequence charSequence) {
if(null == charSequenceList){
throw new CrawlerForJException("charSequenceList could not be null");
}
if(null == charSequence || charSequence.length() <= 0){
throw new CrawlerForJException("charSequence need non empty");
}
char[] csqChars = charSequence.toString().toCharArray();
char[] initialLowerCsqChar = new char[csqChars.length];
initialLowerTransfer(initialLowerCsqChar, csqChars);
charSequenceList.add(new String(initialLowerCsqChar));
}
private static void initialLowerTransfer(char[] targetChar, char[] originChar){
ExcpUtils.throwExpIfFalse(ArrayUtils.isNotEmpty(targetChar),
"targetChar is empty");
ExcpUtils.throwExpIfFalse(ArrayUtils.isNotEmpty(originChar),
"originChar is empty");
int totalLength;
ExcpUtils.throwExpIfFalse((totalLength = originChar.length) ==
targetChar.length,
"targetChar'length not equals to originChar's length");
char[] temp;int tempSize;
System.arraycopy((temp = new char[]{Character.toLowerCase(originChar[0])}), 0 , targetChar, 0, (tempSize = temp.length));
if(totalLength > tempSize){
System.arraycopy(originChar, tempSize, targetChar, tempSize, totalLength - tempSize);
}
}
public static void main(String[] args) {
System.out.println(underlineTransferSmallHump("_As1_s_ANd1A_aa_"));
System.out.println(underlineTransferSmallHump("a"));
System.out.println(underlineTransferSmallHump("A"));
System.out.println(underlineTransferSmallHump("12abc"));
System.out.println(underlineTransferSmallHump("createTime"));
System.out.println(underlineTransferSmallHump("create_Time"));
System.out.println(underlineTransferSmallHump("Create_time"));
System.out.println(underlineTransferSmallHump("Ada1cAa2BDFa"));
System.out.println(underlineTransferSmallHump("___aHb__3AH_aJK"));
}
}