hibernate（三）:hibernate映射关系

hibernate（3）:hibernate映射关系

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例：建表脚本

create table customers(    id bigint not null,    name varchar(15),    primary key (id))create table orders(    id bigint not null,    order_number varchar(15),    customer_id bigint not null,    primary key(id))alter table orders add index idx_customer_id(customer_id),add constraint fk_customer_id foreign key(customer_id) references customers(id);

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Customer.java

package com.hibernate.model;import java.util.Set;public class Customer {private Long id;private String name;private Set orders;public Customer(String name,Set orders){this.name = name;this.orders = orders;}public Customer(){}public Customer(Set orders){this.orders = orders;}public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Set getOrders() {return orders;}public void setOrders(Set orders) {this.orders = orders;}}

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Order.java

package com.hibernate.model;public class Order {private Long id;private String orderNumber;private Customer customer; // 多对一，通过该变量可以引用到对应的Customerpublic Order(String orderNumber, Customer customer) {this.orderNumber = orderNumber;this.customer = customer;}public Order(){}public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getOrderNumber() {return orderNumber;}public void setOrderNumber(String orderNumber) {this.orderNumber = orderNumber;}public Customer getCustomer() {return customer;}public void setCustomer(Customer customer) {this.customer = customer;}}

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Customer.hbm.xml

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"      "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.hibernate.model.Customer" table="customers"><id name="id" column="id" type="long"><generator type="string"><column name="name" length="15"></column></property><!--cascade表示保存或更新customers对象时，会同步保存或更新与之关联的orders对象 --><!-- 因为Customer类中的orders属性是set类型的，所以下面这样用 --><!-- inverse为true表示由对方来维护关联关系 --><set name="orders" cascade="save-update" inverse="true"><key column="customer_id"></key><!-- key元素设定与所关联的持久化类对应的表单外键--><one-to-many name="code"><?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"      "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.hibernate.model.Order" table="orders"><id name="id" column="id" type="long"><generator type="string"><column name="order_number" length="15"></column></property><many-to-one name="customer" column="customer_id" name="code"><mapping resource="Customer.hbm.xml"></mapping><mapping resource="Order.hbm.xml"></mapping>

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测试

package com.hibernate.util;import java.util.HashSet;import org.hibernate.Session;import org.hibernate.Transaction;import com.hibernate.model.Customer;import com.hibernate.model.Order;public class Test {public static void main(String[] args) {saveCustomerAndOrderWithCascade();}public static void saveCustomerAndOrderWithCascade() {Session session = HibernateUtil.currentSession();Transaction tx = null;try {tx = session.beginTransaction();Customer customer = new Customer("zhangsan", new HashSet());Order order1 = new Order();order1.setOrderNumber("zhangsan_order1");order1.setCustomer(customer);Order order2 = new Order();order2.setOrderNumber("zhangsan_order2");order2.setCustomer(customer);Order order3 = new Order();order3.setOrderNumber("zhangsan_order3");order3.setCustomer(customer);customer.getOrders().add(order1);customer.getOrders().add(order2);customer.getOrders().add(order3);//只需要customer，与其关联的order都会被保存session.save(customer);tx.commit();} catch (Exception e) {e.printStackTrace();}finally{HibernateUtil.closeSession(session);}}}

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建表脚本

create table categories(    id bigint not null,    name varchar(15),    category_id bigint,    primary key(id))alter table categories add index idx_category_id (category_id),add constraint fk_category_id foreign key (category_id) references categories(id)

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Category.java

package com.hibernate.model;import java.util.Set;public class Category {private Long id;private String name;private Category parentCategory;private Set childCategories;public Category(String name,Category parentCategory,Set childCategories){this.name = name;this.parentCategory = parentCategory;this.childCategories = childCategories;}public Category(){}public Category(Set childCategories){this.childCategories = childCategories;}public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Category getParentCategory() {return parentCategory;}public void setParentCategory(Category parentCategory) {this.parentCategory = parentCategory;}public Set getChildCategories() {return childCategories;}public void setChildCategories(Set childCategories) {this.childCategories = childCategories;}}

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Category.hbm.xml

<?xml version="1.0"?><!DOCTYPE hibernate-mapping PUBLIC        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"      "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping><class name="com.hibernate.model.Category" table="categories"><id name="id" column="id" type="long"><generator type="string"><column name="name" length="15"></column></property><set name="childCategories" cascade="all" inverse="true"><key column="category_id"></key><one-to-many column="category_id" name="code">public static void saveCategoryWithCascade(){Session session = HibernateUtil.currentSession();Transaction tx = null;try{tx = session.beginTransaction();//食品分类Category foodCategory = new Category("food",null,new HashSet());//蔬菜分类Category vegetableCategory = new Category("vegetable",null,new HashSet());//水果分类Category fruitCategory = new Category("fruit",null,new HashSet());//西红柿分类Category tomotaCategory = new Category("tomota",null,new HashSet());//苹果分类Category appleCategory = new Category("apple",null,new HashSet());//桔子分类Category orangeCategory = new Category("orange",null,new HashSet());//设置上下级关系foodCategory.getChildCategories().add(vegetableCategory);  //食品与蔬菜vegetableCategory.setParentCategory(foodCategory);foodCategory.getChildCategories().add(fruitCategory);  //食品与水果fruitCategory.setParentCategory(foodCategory);vegetableCategory.getChildCategories().add(tomotaCategory);//蔬菜与西红柿tomotaCategory.setParentCategory(vegetableCategory);fruitCategory.getChildCategories().add(appleCategory);  //水果与苹果appleCategory.setParentCategory(fruitCategory);orangeCategory.getChildCategories().add(orangeCategory);  //水果与桔子orangeCategory.setParentCategory(fruitCategory);session.save(foodCategory);  //级联保存所有的关联对象tx.commit();}catch (Exception e) {e.printStackTrace();}finally{HibernateUtil.closeSession(session);}}//级联删除public static void deleteCategoryWithCascade(){Session session = HibernateUtil.currentSession();Transaction tx = null;try{tx = session.beginTransaction();Category category = (Category) session.get(Category.class, new Long(1));session.delete(category);tx.commit();}catch (Exception e) {e.printStackTrace();}finally{HibernateUtil.closeSession(session);}}

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