将”“转换成驼峰，将驼峰转换成”“。

    1. import java.util.regex.Matcher;
    2. import java.util.regex.Pattern;
    4. /**
    5.  * 驼峰转换
    6.  * @author 胡汉三
    7.  * 2017年1月19日 下午4:42:58
    8.  */
    9. public class BeanHump {
    11.     //转变的依赖字符
    12.     public static final char UNDERLINE='_';
    14.     /**
    15.      * 将驼峰转换成"_"(userId:user_id)
    16.      * @param param
    17.      * @return
    18.      */
    19.     public static String camelToUnderline(String param){  
    20.         if (param==null||"".equals(param.trim())){  
    21.             return "";  
    22.         }  
    23.         int len=param.length();  
    24.         StringBuilder sb=new StringBuilder(len);  
    25.         for (int i = 0; i < len; i++) {  
    26.             char c=param.charAt(i);  
    27.             if (Character.isUpperCase(c)){  
    28.                 sb.append(UNDERLINE);  
    29.                 sb.append(Character.toLowerCase(c));  
    30.             }else{  
    31.                 sb.append(c);  
    32.             }  
    33.         }  
    34.         return sb.toString();  
    35.     }
    36.     /**
    37.      * 将"_"转成驼峰(user_id:userId)
    38.      * @param param
    39.      * @return
    40.      */
    41.     public static String underlineToCamel(String param){  
    42.         if (param==null||"".equals(param.trim())){  
    43.             return "";  
    44.         }  
    45.         int len=param.length();  
    46.         StringBuilder sb=new StringBuilder(len);  
    47.         for (int i = 0; i < len; i++) {  
    48.             char c=param.charAt(i);  
    49.             if (c==UNDERLINE){  
    50.                 if (++i<len){  
    51.                     sb.append(Character.toUpperCase(param.charAt(i)));  
    52.                 }  
    53.             }else{  
    54.                 sb.append(c);  
    55.             }  
    56.         }  
    57.         return sb.toString();  
    58.     }
    59.     /**
    60.      * 将"_"转成驼峰(user_id:userId)
    61.      * @param param
    62.      * @return
    63.      */
    64.     public static String underlineToCamel2(String param){  
    65.         if (param==null||"".equals(param.trim())){  
    66.             return "";  
    67.         }  
    68.         StringBuilder sb=new StringBuilder(param);  
    69.         Matcher mc= Pattern.compile(UNDERLINE+"").matcher(param);  
    70.         int i=0;  
    71.         while (mc.find()){  
    72.             int position=mc.end()-(i++);  
    73.             String.valueOf(Character.toUpperCase(sb.charAt(position)));  
    74.             sb.replace(position-1,position+1,sb.substring(position,position+1).toUpperCase());  
    75.         }  
    76.         return sb.toString();  
    77.     } 
    79.     /*
    80.      * 测试
    81.      */
    82.     public static void main(String[] args) {
    83.         System.out.println(camelToUnderline("userNameAll"));
    84.         System.out.println(underlineToCamel("user_name_all"));
    85.         System.out.println(underlineToCamel2("user_name_all"));
    86.     }
    87. }

    运行结果：
    java 驼峰转换 - 图1
    原文链接：https://blog.csdn.net/hzw2312/article/details/54617733