Java实现驼峰和下划线互相转换的示例代码

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

public class UnderlineToCamelUtils {
  
 
 public static String underlineToCamel(String line,boolean smallCamel){
  if(line==null||"".equals(line)){
   return "";
  }
  StringBuffer sb=new StringBuffer();
  Pattern pattern=Pattern.compile("([A-Za-z\\d]+)(_)?");
  Matcher matcher=pattern.matcher(line);
  while(matcher.find()){
   String Word=matcher.group();
   sb.append(smallCamel&&matcher.start()==0?Character.toLowerCase(word.charAt(0)):Character.toUpperCase(word.charAt(0)));
   int index=word.lastIndexOf('_');
   if(index>0){
    sb.append(word.substring(1, index).toLowerCase());
   }else{
    sb.append(word.substring(1).toLowerCase());
   }
  }
  return sb.toString();
 }
 
 public static String camelToUnderline(String line){
  if(line==null||"".equals(line)){
   return "";
  }
  line=String.valueOf(line.charAt(0)).toUpperCase().concat(line.substring(1));
  StringBuffer sb=new StringBuffer();
  Pattern pattern=Pattern.compile("[A-Z]([a-z\\d]+)?");
  Matcher matcher=pattern.matcher(line);
  while(matcher.find()){
   String word=matcher.group();
   sb.append(word.toUpperCase());
   sb.append(matcher.end()==line.length()?"":"_");
  }
  return sb.toString();
 }
}

 public static void main(String[] args) {
  String line="I_HAVE_AN_IPANG3_PIG";
  String camel=underlineToCamel(line,true);
  System.out.println(camel);
  System.out.println(camelToUnderline(camel));
 }

   
    public static String humpToUnderline(String str) {
        Pattern compile = Pattern.compile("[A-Z]");
        Matcher matcher = compile.matcher(str);
        StringBuffer sb = new StringBuffer();
        while(matcher.find()) {
            matcher.appendReplacement(sb,  "_" + matcher.group(0).toLowerCase());
        }
        matcher.appendTail(sb);
        return sb.toString();
    }

 
    public static String underlineToHump(String str) {
        str = str.toLowerCase();
        Pattern compile = Pattern.compile("_[a-z]");
        Matcher matcher = compile.matcher(str);
        StringBuffer sb = new StringBuffer();
        while(matcher.find()) {
            matcher.appendReplacement(sb,  matcher.group(0).toUpperCase().replace("_",""));
        }
        matcher.appendTail(sb);
        return sb.toString();
    }