hibernate注解

package com.b510.examples;

import java.util.HashSet;
import java.util.Set;

// 标准注解

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

//增加的注解

import org.hibernate.annotations.GenericGenerator;

//当前的类是一个持久化类，是Category这个类。他映射了一个表category。所对应的 数据库是users
//这句：@Table(name = "category", catalog = "users")  可以省略
@Entity
@Table(name = "category", catalog = "users")

public class Category implements java.io.Serializable {

 private static final long serialVersionUID = 3240281547213597385L;
 private Integer id;
 private String name;
 private String description;
 private Set<Product> products = new HashSet<Product>(0);

 
 public Category() {
 }

 public Category(String name, String description, Set<Product> products) {
  this.name = name;
  this.description = description;
  this.products = products;
 }

 // 主键 ：@Id    主键生成方式：strategy = "increment"
 //映射表中id这个字段，不能为空，并且是唯一的
 @GenericGenerator(name = "generator", strategy = "increment")
 @Id
 @GeneratedValue(generator = "generator")
 @Column(name = "id", unique = true, nullable = false)
 public Integer getId() {
  return this.id;
 }

 public void setId(Integer id) {
  this.id = id;
 }

 //映射表中name这个字段 ，长度是500
 @Column(name = "name", length = 500)
 public String getName() {
  return this.name;
 }

 public void setName(String name) {
  this.name = name;
 }
 
 //映射表中description这个字段 ，长度是500
 @Column(name = "description", length = 500)
 public String getDescription() {
  return this.description;
 }

 public void setDescription(String description) {
  this.description = description;
 }

 //级联操作：cascade = CascadeType.ALL
 //延迟加载：fetch = FetchType.LAZY
 //映射：mappedBy = "category"
 //一对多方式
 @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "category")
 public Set<Product> getProducts() {
  return this.products;
 }

 public void setProducts(Set<Product> products) {
  this.products = products;
 }

}

 

 

package com.b510.examples;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;


@Entity
@Table(name = "product", catalog = "users")
public class Product implements java.io.Serializable {

 private static final long serialVersionUID = -1546206493725028472L;
 private Integer id;
 private Category category;
 private String name;
 private String price;
 private String descripton;

 
 public Product() {
 }

 public Product(Category category, String name, String price,
   String descripton) {
  this.category = category;
  this.name = name;
  this.price = price;
  this.descripton = descripton;
 }
 
 @GenericGenerator(name = "generator", strategy = "increment")
 @Id
 @GeneratedValue(generator = "generator")
 @Column(name = "id", unique = true, nullable = false)
 public Integer getId() {
  return this.id;
 }

 public void setId(Integer id) {
  this.id = id;
 }

 //延迟加载：多对一方式
 //关联信息：外键name = "category_id"
 @ManyToOne(fetch = FetchType.LAZY)
 @JoinColumn(name = "category_id")
 public Category getCategory() {
  return this.category;
 }

 public void setCategory(Category category) {
  this.category = category;
 }

 @Column(name = "name", length = 500)
 public String getName() {
  return this.name;
 }

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

 @Column(name = "price", length = 10)
 public String getPrice() {
  return this.price;
 }

 public void setPrice(String price) {
  this.price = price;
 }

 @Column(name = "descripton", length = 500)
 public String getDescripton() {
  return this.descripton;
 }

 public void setDescripton(String descripton) {
  this.descripton = descripton;
 }

}