public class FieldPropertyConvert {

public static void main(String[] args) {
System.out.println(propertyToField("userName"));
System.out.println(fieldToProperty("user_name"));
}

/**
* 判断是否是大写字母
* @param c
* @return
*/
public static Boolean isUp(char c){
if (c >= 'A' && c <= 'Z') {
return true;
}
return false;
}

/**
* java对象属性转换为数据库字段，如userName-->user_name
* @param property
* @return
*/
public static String propertyToField(String property) {
if (null == property) {
return "";
}
char[] chars = property.toCharArray();
StringBuffer field = new StringBuffer();
for (char c : chars) {
if (isUp(c)) {
field.append("_" + String.valueOf(c).toLowerCase());
} else {
field.append(c);
}
}
return field.toString();
}

/**
* 将数据库字段转换为java属性，如user_name-->userName
* @param field 字段名
* @return
*/
public static String fieldToProperty(String field) {
if (null == field) {
return "";
}
char[] chars = field.toCharArray();
StringBuffer property = new StringBuffer();
for (int i = 0; i < chars.length; i++) {
char c = chars[i];
if (c == '_') {
int j = i + 1;
if (j < chars.length) {
property.append(String.valueOf(chars[j]).toUpperCase());
i++;
}
} else {
property.append(c);
}
}
return property.toString();
}

}