java之驼峰转下划线

package com.punk.nio.demo;

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

public class Demo{

    private static Pattern linePattern = Pattern.compile("_(\\w)");
    /**下划线转驼峰*/
    public static String lineToHump(String str){
        str = str.toLowerCase();
        Matcher matcher = linePattern.matcher(str);
        StringBuffer sb = new StringBuffer();
        while(matcher.find()){
            matcher.appendReplacement(sb, matcher.group(1).toUpperCase());
        }
        matcher.appendTail(sb);
        return sb.toString();
    }
    /**驼峰转下划线*/
    public static String humpToLine(String str){
        return str.replaceAll("[A-Z]", "_$0").toLowerCase();
    }
    private static Pattern humpPattern = Pattern.compile("[A-Z]");
    /**驼峰转下划线,效率比上面高*/
    public static String humpToLine2(String str){
        Matcher matcher = humpPattern.matcher(str);
        StringBuffer sb = new StringBuffer();
        while(matcher.find()){
            matcher.appendReplacement(sb, "_"+matcher.group(0).toLowerCase());
        }
        matcher.appendTail(sb);
        return sb.toString();
    }
    public static void main(String[] args) {
        String lineToHump = lineToHump("f_parent_no_leader");
        System.out.println(lineToHump);//fParentNoLeader
        System.out.println(humpToLine(lineToHump));//f_parent_no_leader
        System.out.println(humpToLine2(lineToHump));//f_parent_no_leader
    }
}