JAVA+Hibernate 無限級分類

資料庫結構：
Create TABLE `admin_menu` (
`menu_id` int(4) NOT NULL auto_increment,
`menu_name` varchar(50) default NULL,
`parent_id` int(4) default '0',
`menu_value` varchar(255) default NULL,
`menu_sort` int(4) default '0',
`menu_description` varchar(50) default NULL,
`isvalid` tinyint(1) default '0',
PRIMARY KEY (`menu_id`)
)

主要看menu_id和parent_id這兩個欄位。
Eclipse產生的表持久映射：(說明：自己加level屬性,作用：為了記錄種類所在深度)
public class AdminMenu implements java.io.Serializable {
// Fields
private Integer menuId;
private String menuName;
private Integer parentId;
private String menuValue;
private Integer menuSort;
private String menuDescription;
private Short isvalid;
private int level;

// Constructors

/** default constructor */
public AdminMenu() {
}

/** minimal constructor */
public AdminMenu(Integer menuId) {
this.menuId = menuId;
}

/** full constructor */
public AdminMenu(Integer menuId, String menuName, Integer parentId, String menuValue, Integer menuSort, String menuDescription, Short isvalid) {
this.menuId = menuId;
this.menuName = menuName;
this.parentId = parentId;
this.menuValue = menuValue;
this.menuSort = menuSort;
this.menuDescription = menuDescription;
this.isvalid = isvalid;
}

// Property accessors

public Integer getMenuId() {
return this.menuId;
}

public void setMenuId(Integer menuId) {
this.menuId = menuId;
}

public String getMenuName() {
return this.menuName;
}

public void setMenuName(String menuName) {
this.menuName = menuName;
}

public Integer getParentId() {
return this.parentId;
}

public void setParentId(Integer parentId) {
this.parentId = parentId;
}

public String getMenuValue() {
return this.menuValue;
}

public void setMenuValue(String menuValue) {
this.menuValue = menuValue;
}

public Integer getMenuSort() {
return this.menuSort;
}

public void setMenuSort(Integer menuSort) {
this.menuSort = menuSort;
}

public String getMenuDescription() {
return this.menuDescription;
}

public void setMenuDescription(String menuDescription) {
this.menuDescription = menuDescription;
}

public Short getIsvalid() {
return this.isvalid;
}

public void setIsvalid(Short isvalid) {
this.isvalid = isvalid;
}

public int getLevel()
{
return level;
}

public void setLevel(int level)
{
this.level = level;
}

}

/**
* 查詢管理員菜單
*
* @return
*/
public static AdminMenu[] selectAdminMenu(String condition)
{
AdminMenu[] adminMenu = null;
String hql = "from AdminMenu as am" + condition;
List list = select(hql);

Object[] o = list.toArray();
if(o != null)
{
adminMenu = new AdminMenu[o.length];
for(int i = 0; i < o.length; i++)
{
adminMenu[i] = (AdminMenu)o[i];
}
}
return adminMenu;
}

/**
* 樹的產生(主要用數組進行遞迴)
*
* @return
*/
public static ArrayList getTree(AdminMenu[] menu, int parentId, int level, ArrayList list)
{
for(int i = 0; i < menu.length; i++)
{
if(menu[i].getParentId().intValue() == parentId)
{
menu[i].setLevel(level);
list.add(menu[i]);
getTree(menu, menu[i].getMenuId(), level+1, list);
}
}
return list;
}