java驼峰转换的方法

import java.util.regex.Matcher;import java.util.regex.Pattern; /** * 驼峰转换 * @author 胡汉三 * 2017年1月19日 下午4:42:58 */public class BeanHump {  //转变的依赖字符 public static final char UNDERLINE='_';  /** * 将驼峰转换成"_"(userId:user_id) * @param param * @return */ public static String camelToUnderline(String param){  if (param==null||"".equals(param.trim())){   return "";  }  int len=param.length();  StringBuilder sb=new StringBuilder(len);  for (int i = 0; i < len; i++) {   char c=param.charAt(i);   if (Character.isUpperCase(c)){   sb.append(UNDERLINE);   sb.append(Character.toLowerCase(c));   }else{   sb.append(c);   }  }  return sb.toString();  } /** * 将"_"转成驼峰(user_id:userId) * @param param * @return */ public static String underlineToCamel(String param){  if (param==null||"".equals(param.trim())){   return "";  }  int len=param.length();  StringBuilder sb=new StringBuilder(len);  for (int i = 0; i < len; i++) {   char c=param.charAt(i);   if (c==UNDERLINE){   if (++i<len){    sb.append(Character.toUpperCase(param.charAt(i)));   }   }else{   sb.append(c);   }  }  return sb.toString();  } /** * 将"_"转成驼峰(user_id:userId) * @param param * @return */ public static String underlineToCamel2(String param){  if (param==null||"".equals(param.trim())){   return "";  }  StringBuilder sb=new StringBuilder(param);  Matcher mc= Pattern.compile(UNDERLINE+"").matcher(param);  int i=0;  while (mc.find()){   int position=mc.end()-(i++);   String.valueOf(Character.toUpperCase(sb.charAt(position)));   sb.replace(position-1,position+1,sb.substring(position,position+1).toUpperCase());  }  return sb.toString();  }   /* * 测试 */ public static void main(String[] args) { System.out.println(camelToUnderline("userNameAll")); System.out.println(underlineToCamel("user_name_all")); System.out.println(underlineToCamel2("user_name_all")); }}