category.ejb

J2EE的一个开发实例

package music.ejb.db;

import java.util.*;
import javax.ejb.*;
import weblogic.ejb.*;

import music.ejb.JndiHelper;
import music.shared.*;

/**
 * @ejbgen:entity default-transaction="Required" prim-key-class="java.lang.Integer"
 *   ejb-name = "Category"
 *   data-source-name="jdbc/MusicDataSource"
 *   table-name = "category"
 *   abstract-schema-name = "Category"
 *
 * @ejbgen:jndi-name
 *   local="ejb/Category"
 *
 * @ejbgen:file-generation local-class = "True" local-class-name = "CategoryLocal" local-home = "True" local-home-name="CategoryLocalHome" remote-class = "False" remote-home = "False"  remote-home-name = "CatalogRemoteHome" remote-class-name = "CatalogRemote" value-class = "False" value-class-name = "CategoryValue" pk-class = "True"
 *
 * @ejbgen:finder ejb-ql="SELECT OBJECT(o) from Category as o where o.parentId=0" generate-on="Local" signature="java.util.Collection findRootCategories()"
 * @ejbgen:relation role-name="Category-has-Artists" cmr-field="artists" target-ejb="Artist" multiplicity="One" name="Category-Artist"
 * @ejbgen:automatic-key-generation name="id" type="SQLServer2000"
 * @ejbgen:finder ejb-ql="SELECT OBJECT(o) from Category as o where o.parentId = ?1" generate-on="Local" signature="java.util.Collection findByParentId(int parentId)"
 */
public abstract class Category extends GenericEntityBean implements EntityBean
{

    /**
     * @ejbgen:cmp-field ordering-number="10" primkey-field="true" column="Id"
     * @ejbgen:local-method
     */
    public abstract Integer getId();

    /**
     */
    public abstract void setId(Integer arg);

    /**
     * @ejbgen:cmp-field column="Name"
     * @ejbgen:local-method
     */
    public abstract String getName();

    /**
     * @ejbgen:local-method
     */
    public abstract void setName(String arg);

    /**
     * @ejbgen:cmp-field column="ParentId"
     * @ejbgen:local-method
     */
    public abstract int getParentId();

    /**
     */
    public abstract void setParentId(int arg);

    /**
     * @ejbgen:cmr-field
     * @ejbgen:local-method
     */
    public abstract java.util.Collection getArtists();

    /**
     * @ejbgen:local-method
     */
    public abstract void setArtists(java.util.Collection arg);

    public java.lang.Integer ejbCreate(int ParentId, java.lang.String Name)
    {
      setParentId(ParentId);
      setName(Name);

      return null; // FIXME return PK value 
    }

    public void ejbPostCreate(int ParentId, java.lang.String Name)
    {
    }

    /**
     * @ejbgen:local-method
     */
    public CategoryVO copy()
    {
        return new CategoryVO(getId().intValue(), getParentId(), getName());
    }

    /**
     * fullPath() return the full path of the current category.
     * For example: category "Female".fullPath() may return "Pop","English","Female",
     * the type of the element(s) in the collection is CategoryVO
     * @ejbgen:local-method
     */
    public Collection fullPath()
    {
        LinkedList c = new LinkedList();
        LinkedList ids = new LinkedList(); // 记录添加的ID

        CategoryVO p = copy();
        c.add(p); // add myself!
        ids.add(getId());

        CategoryLocal category = null;
        CategoryLocalHome home = JndiHelper.getCategoryLocalHome();

        while(true) {
            if(p.getParentId()==0) // 已经到达最顶层
                break;
            if(ids.contains(new Integer(p.getParentId()))) // 必须确保Category不会循环引用
                break;
            // 获得parentId:
            try {
                category = home.findByPrimaryKey(new Integer(p.getParentId()));
                ids.add(new Integer(p.getParentId()));
            }
            catch(FinderException fe) {
                break;
            }
            p = category.copy();
            c.addFirst(p);
        }
        return c;
    }

    /**
     * return the parent category, if current is the top category, a FinderException will be thrown.
     * @ejbgen:local-method
     */
    public CategoryLocal parent() throws FinderException
    {
        int id = getParentId();
        if(id==0)
            throw new FinderException("No parent category.");
        return JndiHelper.getCategoryLocalHome().findByPrimaryKey(new Integer(id));
    }
}