数据库字段 驼峰风格 互相转换

 /**
    * 将以下划线分隔的数据库字段转换为驼峰风格的字符串
     * @param fieldName
     * @return
    */
    public static String changeColumnToFieldName(String columnName) {
        String[] array = columnName.split("_");
        StringBuffer sb = null;
        for (String cn : array) {
            cn = cn.toLowerCase();
            if (sb == null) {
                sb = new StringBuffer(cn);
                continue;
            }
            sb.append(cn.substring(0, 1).toUpperCase()).append(cn.substring(1));
        }
        return sb.toString();
    }

/**
 * 将驼峰风格的字符串转换为以下划线分隔的数据库字段
 * 
 * @param fieldName
 * @return
 */
public static String changeFieldToColumnName(String fieldName) {
    if (fieldName == null) {
        return null;
    }
    StringBuffer columnName = new StringBuffer();
    int length = fieldName.length();
    for (int i = 0; i < length; i++) {
        char c = fieldName.charAt(i);
        if ('A' <= c && 'Z' >= c) {
            columnName.append("_").append((char) (c + 32));
        } else {
            columnName.append(fieldName.charAt(i));
        }
    }
    return columnName.toString();
}