java驼峰法和下划线法字符串的相互转换

 1 import java.util.regex.Matcher;

 import java.util.regex.Pattern;

 public class CamelAndUnderLineConverter {

     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(简单写法，效率低于{@link #humpToLine2(String)})

      */

     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

     }

 }