category.java

用struts2＋jpa来实现了对音乐

package net.jeffrey.hibernate;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Entity;
import javax.persistence.OneToMany;
import net.jeffrey.hibernate.history.Historizable;
import org.hibernate.annotations.Cascade;

/**
 * 商品分类
 * @author jeffrey
 */
@Entity
public class Category extends AbstractEntity implements Serializable, Historizable {
    
    private String name;
    
    @OneToMany(mappedBy = "category")
    // 定义级联，必须使用hibernate的级联annotation，JPA的Cascade不起作用
    @Cascade(org.hibernate.annotations.CascadeType.ALL)
    private List<Product> products = new ArrayList<Product>();

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Product> getProducts() {
        return products;
    }

    public void setProducts(List<Product> products) {
        this.products = products;
    }
    
    /* Helper方法，在添加商品的同时建立双方的关联关系 */
    public void addProduct(Product p) {
        if (p != null) {
            p.setCategory(this);
            this.products.add(p);
        }
    }
    
    /* Helper方法，在删除商品的同时解除双方的关联关系 */
    public void removeProduct(Product p) {
        if (p != null) {
            p.setCategory(null);
            this.products.remove(p);
        }
    }

    @Override
    public String toString() {
        return "Category[" + id + "," + name + "]";
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Category other = (Category) obj;
        if (this.id != other.id && (this.id == null || !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode() {
        int hash = 3;
        return hash = 47 * hash + id;
    }
}