Java框架之Hibernate实战篇
2020-06-09 16:02:02来源:博客园 阅读 ()
Java框架之Hibernate实战篇
从零开始Hibernate实战篇:(四篇实战代码,循序渐进,注意事项和学习内容在代码注释里面,面向有一定基础的同学使用)
第一篇:基础篇(搭建)
Hibernate开发基本步骤:
1.导入jar包(hibernate-release-5.0.7.Final\lib的文件里面去找所需要的jar包)
2.写实体类+实体类的映射文件
User.java
/** * Project Name:hibernate_demo * File Name:User.java * Package Name:cn.itcast.entity * */ package cn.itcast.entity; /** * @author zhouP * @version * @see */ public class User { // hibernate要求实体类有一个属性唯一的 private int uid; private String username; private String password; private String address; public void setUid(int uid) { this.uid = uid; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public int getUid() { return uid; } }
User.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <!-- 1.配置类和表对应 class属性:实体类全路径(类路径) table属性:数据库表名称 --> <class name="cn.itcast.entity.User" table="t_user"> <!-- 2.配置实体类id与表id对应 hibernate要求实体类有一个属性唯一值 hibernate要求表有字段作为唯一值 --> <!-- id标签 name属性:实体类里面id属性名称 column属性:生成的表字段名称 --> <id name="uid" column="uid"> <!-- 配置数据库表id的增长策略 native:主键自动增长 --> <generator class="native"></generator> </id> <!-- 配置其他属性和表字段对应 name属性:实体类属性名称 column属性:生成表字段名称 --> <property name="username" column="username"></property> <property name="password" column="password"></property> <property name="address" column="address"></property> </class> </hibernate-mapping>
3.Hibernate核心配置文件
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- 第一部分:配置数据库信息(必须的) --> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql:///hibernate_test</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <!-- 第二部分:配置hibernate信息(可选的) --> <property name="hibernate.show_sql">true</property> <property name="hibernate.format_sql">true</property> <!-- 两个重要配置ddl、dialect(分页时用) --> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <!-- 第三部分:把映射文件放到核心配置文件中(必须的)(文件路径) --> <mapping resource="cn/itcast/entity/User.hbm.xml"/> </session-factory> </hibernate-configuration>
4.编写Hibernate工具类
package cn.itcast.utils; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtils { // 创建sessionFactory的过程,特别浪费资源,建议一个项目一般创建一个sessionFactory对象 // static Configuration cfg = null; static SessionFactory sessionFactory = null; // 静态代码块实现 static { // cfg = new Configuration(); // cfg.configure(); // sessionFactory = cfg.buildSessionFactory(); sessionFactory = new Configuration().configure().buildSessionFactory(); } // 提供方法返回sessionFactory public static SessionFactory getSessionFactory() { return sessionFactory; } }
5.测试代码
package cn.itcast.hibernatetest; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.User; import cn.itcast.utils.HibernateUtils; public class HibernateDemo { @Test public void testAdd() { // 第一步:加载hibernate核心配置文件 // Configuration cfg = new Configuration(); // cfg.configure(); // 第二步:创建SessionFactory对象 // SessionFactory sessionFactory = cfg.buildSessionFactory(); SessionFactory sessionFactory = HibernateUtils.getSessionFactory(); // 第三步:使用SessionFactory创建session对象 Session session = sessionFactory.openSession(); // 第四步:开启事务 Transaction tx = session.beginTransaction(); // 第五步:写具体的逻辑 curd操作 // 添加功能 User user = new User(); user.setUsername("Mr Li"); user.setPassword("1234"); user.setAddress("武汉"); // 调用session的方法实现添加 session.save(user); // 第六步:提交事务 tx.commit(); // 第七步:关闭资源 session.close(); sessionFactory.close(); } }
第二篇:Hibernate API 练习篇
1.创建项目(略)2.导入jar包(略)3.实体类+其映射文件(略)
4.Hibernate核心配置文件
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql:///hibernate_test2</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.show_sql">true</property> <property name="hibernate.format_sql">true</property> <property name="hibernate.hbm2ddl.auto">update</property> <!-- 在hibernate核心配置文件中配置 --> <property name="hibernate.current_session_context_class">thread</property> <!-- 把映射文件放到hibernate核心配置文件当中 --> <mapping resource="cn/itcast/entity/User.cfg.xml"/> </session-factory> </hibernate-configuration>
5.Hibernate相关测试代码:
(1)HibernateDemo.java
package cn.itcast.hibernatetest; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.User; import cn.itcast.utils.HibernateUtils; public class HibernateDemo { @Test public void testSaveOrUpdate() { // 1.调用工具类得到sessionFactory SessionFactory sessionFactory = HibernateUtils.getSessionFactory(); // 2.获取session Session session = sessionFactory.openSession(); // 3.开启事务 Transaction tx = session.beginTransaction(); // 4.添加操作 // User user = new User(); // user.setUid(1); // user.setUsername("王第一"); // user.setPassword("12345"); // user.setAddress("杏林二小"); // session.save(user); // 把uid=1的记录username修改 // User user = new User(); // user.setUid(1); // user.setUsername("韩梅梅梅"); // session.save(user);要用update // session.update(user); // User user = session.get(User.class, 2); // user.setAddress("兴隆林业局"); // // 实体类对象是持久态,做修改 // session.saveOrUpdate(user); // User user = new User(); // user.setUsername("rose"); // user.setPassword("1314"); // user.setAddress("阿尔巴尼亚"); // session.save(user); // User user = new User(); // user.setUsername("jack"); // user.setPassword("520"); // user.setAddress("朝鲜"); // session.save(user); User user = new User(); user.setUsername("jack"); user.setPassword("124"); user.setAddress("china"); session.save(user); // 5.提交事务 try { tx.commit(); } catch (Exception e) { tx.rollback(); } finally { // 6.关闭资源 session.close(); sessionFactory.close(); } } @Test public void testDelete() { // 1.利用工具类创建sessionFactory SessionFactory sessionFactory = HibernateUtils.getSessionFactory(); // 2.得到session Session session = sessionFactory.openSession(); // 3.开启事务 Transaction tx = session.beginTransaction(); // 4.删除操作 // 第一种删除方法 // User user = session.get(User.class, 1); // session.delete(user); // 第二种删除方法 User user = new User(); user.setUid(3); session.delete(user); // 5.提交事务 try { tx.commit(); } catch (Exception e) { tx.rollback(); } finally { // 6.关闭资源 session.close(); sessionFactory.close(); } } @Test public void testUpdate() { // 1.工具类中得到sessionFactory SessionFactory sessionFactory = HibernateUtils.getSessionFactory(); // 2.得到session Session session = sessionFactory.openSession(); // 3.开启事务 Transaction tx = session.beginTransaction(); // 4.更新操作(修改uid=2记录的username值) // 4.1根据id查询(如果数据库中没有此id,执行的是查询) User user = session.get(User.class, 2); // 4.2向返回的username对象里面设置修改之后的值 user.setUsername("修改之后的值"); // 4.3调用session的update方法 // 执行过程:到user对象里面找到uid值,根据uid进行修改 session.update(user); // 5.提交事务 try { tx.commit(); } catch (Exception e) { tx.rollback(); } finally { // 6.关闭资源 session.close(); sessionFactory.close(); } } }
(2)HibernateQueryData.java
package cn.itcast.hibernatetest; import java.util.List; import org.hibernate.Criteria; import org.hibernate.Query; import org.hibernate.SQLQuery; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.User; import cn.itcast.utils.HibernateUtils; public class HibernateQueryData { // 使用SQLQuery对象 @Test public void testQuery() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 创建SQLQuery对象 SQLQuery sqlQuery = session.createSQLQuery("select * from t_user"); // 返回的list中的每部分是对象的形式 sqlQuery.addEntity(User.class); // 调用SQLQuery里面的方法...导包是:import java.util.List; @SuppressWarnings("unchecked") List<User> list = sqlQuery.list(); // 验证:当调用SQLQuery方法:返回的list集合,默认里面每一部分是数组结构 for (User user : list) { System.out.println(user); } // List<Object[]> list = sqlQuery.list(); // // for (Object[] objects : list) { // System.out.println(Arrays.toString(objects)); // } // 提交事务 tx.commit(); } catch (Exception e) { tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 使用Criteria对象 @Test public void testCriteria() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 创建criteria对象 Criteria criteria = session.createCriteria(User.class); @SuppressWarnings("unchecked") List<User> list = criteria.list(); for (User user : list) { System.out.println(user); } tx.commit(); } catch (Exception e) { tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 使用query对象 @Test public void demoQuery() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = HibernateUtils.getSessionobject(); // 开启事务 tx = session.beginTransaction(); // 1 创建Query对象 Query query = session.createQuery("from User"); // 2 调用query对象里面的方法得到结果 @SuppressWarnings("unchecked") List<User> list = query.list(); // 遍历list集合四种: 普通for、增强for、迭代器、list迭代器 // 遍历set集合两种:增强for、迭代器 // 遍历map集合两种:得到所有key,根据key得到value; 得到key-value关系 for (User user : list) { System.out.println(user); } // 提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } }
(3)HibernateSelect.java
package cn.itcast.hibernatetest; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.User; import cn.itcast.utils.HibernateUtils; public class HibernateSelect { // 事务规范代码 @Test public void testTx() { Session session = null; Transaction tx = null; try { // 于本地线程绑定的session session = HibernateUtils.getSessionobject(); // 开启事务 tx = session.beginTransaction(); // 添加 User user = new User(); user.setAddress("华丰"); user.setPassword("789"); user.setUsername("化华"); session.save(user); // 模拟出事情了:java.lang.ArithmeticException: / by zero // 10/0 此时,不能插入数据 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { // 下面session不能关闭,JUnit关闭会报错。可以插入数据。 // org.hibernate.SessionException: Session was already closed // org.hibernate.SessionException: Session was already closed // session.close(); } } // 一级缓存特性 @Test public void testDemo() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { // 1.调用工具类得到sessionFactory sessionFactory = HibernateUtils.getSessionFactory(); // 2.获取session session = sessionFactory.openSession(); // 3.开启事务 tx = session.beginTransaction(); // 4.操作:查询 User user = session.get(User.class, 5); user.setAddress("之前室china,现在是哈尔滨"); session.update(user); // 5.提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { // 6.关闭资源 session.close(); sessionFactory.close(); } } // 验证一级缓存存在 @Test public void testCasch() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.根据id=2查询 // 执行第一个get方法是否查询数据库,是否发送语句 User user1 = session.get(User.class, 2); System.out.println(user1); // 2.在 根据id查询 // 执行第二个get方法是否查询数据库,是否发送语句 // 结果是!只有一条查询语句,两条查询结果 User user2 = session.get(User.class, 2); System.out.println(user2); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } }
第三篇:Hibernate 一对多、多对多实战篇
1.cn.itcast.entity包里面:
(1)Customer.java
package cn.itcast.entity; import java.util.HashSet; import java.util.Set; public class Customer { // 用户id private Integer cid; // 用户名称 private String custName; // 用户级别 private String custLevel; // 用户来源 private String custSource; // 联系电话 private String custPhone; // 手机 private String custMobile; // 在客户实体类里面表示多个联系人,一个客户有多个联系人 // hibernate要求使用集合表示多的数据,使用set集合: // import java.util.HashSet;import java.util.Set; private Set<LinkMan> setLinkMan = new HashSet<LinkMan>(); public Set<LinkMan> getSetLinkMan() { return setLinkMan; } public void setSetLinkMan(Set<LinkMan> setLinkMan) { this.setLinkMan = setLinkMan; } public Integer getCid() { return cid; } public void setCid(Integer cid) { this.cid = cid; } public String getCustName() { return custName; } public void setCustName(String custName) { this.custName = custName; } public String getCustLevel() { return custLevel; } public void setCustLevel(String custLevel) { this.custLevel = custLevel; } public String getCustSource() { return custSource; } public void setCustSource(String custSource) { this.custSource = custSource; } public String getCustPhone() { return custPhone; } public void setCustPhone(String custPhone) { this.custPhone = custPhone; } public String getCustMobile() { return custMobile; } public void setCustMobile(String custMobile) { this.custMobile = custMobile; } }
Customer.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" > <hibernate-mapping> <!-- 1.配置类和表对应 class标签 name属性:实体类的全路径 table属性:数据库表名称 --> <class name="cn.itcast.entity.Customer" table="t_customer"> <id name="cid" column="cid"> <generator class="native"></generator> </id> <property name="custName" column="custName"></property> <property name="custLevel" column="custLevel"></property> <property name="custSource" column="custSource"></property> <property name="custPhone" column="custPhone"></property> <property name="custMobile" column="custMobile"></property> <!-- 在客户映射文件中,表示所有联系人 使用set标签:表示所有联系人 set标签里面有name属性:属性值写在客户实体类里面,表示联系人的set集合名称 reverse属性默认值:false表示不放弃维护 true表示放弃维护--> <set name="setLinkMan" inverse="true"> <!-- 一对多建表,有外键 hibernate机制:双向维护外键,在一和多那一方都配置外键 column属性值:外键名称 --> <key column="clid"></key> <!-- 客户所有的联系人,class里面写联系人实体类全路径 --> <one-to-many class="cn.itcast.entity.LinkMan"/> </set> </class> </hibernate-mapping>
(2)LinkMan.java
package cn.itcast.entity; public class LinkMan { // 联系人编号(主键) private Integer lkm_id; // 联系人姓名 private String lkm_name; // 联系人性别 private String lmk_gender; // 联系人办公电话 private String lkm_phone; // 在联系人实体类里面表示所有客户,一个联系人只能属于一个客户 // Customer customer=new Customer(); private Customer customer; public Customer getCustomer() { return customer; } public void setCustomer(Customer customer) { this.customer = customer; } public Integer getLkm_id() { return lkm_id; } public void setLkm_id(Integer lkm_id) { this.lkm_id = lkm_id; } public String getLkm_name() { return lkm_name; } public void setLkm_name(String lkm_name) { this.lkm_name = lkm_name; } public String getLmk_gender() { return lmk_gender; } public void setLmk_gender(String lmk_gender) { this.lmk_gender = lmk_gender; } public String getLkm_phone() { return lkm_phone; } public void setLkm_phone(String lkm_phone) { this.lkm_phone = lkm_phone; } }
LinkMan.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" > <hibernate-mapping> <class name="cn.itcast.entity.LinkMan" table="t_linkman"> <id name="lkm_id" column="lkm_id"> <generator class="native"></generator> </id> <property name="lkm_name" column="lkm_name"></property> <property name="lmk_gender" column="lmk_gender"></property> <property name="lkm_phone" column="lkm_phone"></property> <!-- 表示联系人所属客户 name属性:因为在联系人实体类使用customer对象表示,写customer名称 class属性:customer全路径 column属性:外键名称 --> <many-to-one name="customer" class="cn.itcast.entity.Customer" column="clid"></many-to-one> </class> </hibernate-mapping>
2.HibernateUtils包里面的HibernateUtils.java工具类,添加本地线程绑定的session的方法
package cn.itcast.utils; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtils { // 加载核心配置文件,静态代码块实现 static Configuration cfg = null; static SessionFactory sessionFactory = null; static { cfg = new Configuration(); cfg.configure(); sessionFactory = cfg.buildSessionFactory(); } // 提供返回与本地线程绑定的session的方法 public static Session getSessionObject() { return sessionFactory.getCurrentSession(); } // 提供方法返回sessionFactory public static SessionFactory getSessionFactory() { return sessionFactory; } public static void main(String[] args) { } }
3.Hibernate核心配置文件
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- 第一部分:配置数据库信息,必须的 --> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql:///hibernate_test3</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <!-- 第二部分:配置hibernate信息,可选 --> <property name="hibernate.show_sql">true</property> <property name="hibernate.format_sql">true</property> <property name="hibernate.hbm2ddl.auto">update</property> <!-- 配置数据库方言 在mysql里面实现分页,关键字limit,只能用在mysql里面 在oracle数据库,实现分页rownum 让hibernate框架识别不同数据库的自己特有的语句 --> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.current_session_context_class">thread</property> <!-- 第三部分:把映射文件放到核心配置文件中,必须的--> <mapping resource="cn/itcast/entity/Customer.hbm.xml"/> <mapping resource="cn/itcast/entity/LinkMan.hbm.xml"/> <mapping resource="cn/itcast/manytomany/User.hbm.xml"/> <mapping resource="cn/itcast/manytomany/Role.hbm.xml"/> </session-factory> </hibernate-configuration>
4.Hibernatetest包
(1)HibernateOnetoMany.java
package hibernatetest; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.Customer; import cn.itcast.entity.LinkMan; import cn.itcast.utils.HibernateUtils; public class HibernateOnetoMany { // 演示:一对多级联保存 @Test public void testUpdate() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 添加一个客户,为这个客户添加一个联系人 // 1 创建客户和联系人对象 Customer customer = new Customer(); customer.setCustLevel("vip"); customer.setCustMobile("8888"); customer.setCustName("橡果国际"); customer.setCustPhone("18345782345"); customer.setCustSource("上海"); LinkMan linkman = new LinkMan(); linkman.setLkm_name("王小卓"); linkman.setLkm_phone("173456379876"); linkman.setLmk_gender("女"); // 2 在客户表示所有联系人,在联系人表示客户 // 建立客户对象和联系人对象关系 // 2.1 把联系人对象 放到客户对象的set集合里面 customer.getSetLinkMan().add(linkman); // 2.2 把客户对象放到联系人里面 linkman.setCustomer(customer); // 3 保存到数据库 session.save(customer); session.save(linkman); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:一对多级联保存 @Test public void testAddDemo2() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); Customer customer = new Customer(); customer.setCustLevel("普通"); customer.setCustName("奥克斯"); customer.setCustPhone("18932222237"); customer.setCustSource("北京"); LinkMan linkman = new LinkMan(); linkman.setLkm_name("陈小桥"); linkman.setLkm_phone("15024324567"); linkman.setLmk_gender("女"); customer.getSetLinkMan().add(linkman); // 少了这句,linkman.setCustomer(customer);只执行t_customer表的insert语句 // 添加它和session.save(linkman);,则t_linkman表中添加的新数据(陈小桥)才会加进去 linkman.setCustomer(customer); // save() 保存要有哦! session.save(customer); session.save(linkman); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { // sessionFactory.close(); // session.close(); } } // 演示:一对多级联删除 @Test public void testDeleteDemo() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.根据id查询客户对象 Customer customer = session.get(Customer.class, 12); // 2.调用删除方法 session.delete(customer); // 3.提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); // sessionFactory.close(); } } // 演示:一对多修改 @Test public void testUpdateDemo() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.根据id查询联系人,根据id查询客户 Customer customer1 = session.get(Customer.class, 3); LinkMan linkman1 = session.get(LinkMan.class, 1); // 2.设置持久态对象值 // i.把联系人放到客户里面 customer1.getSetLinkMan().add(linkman1); // ii.把客户放到联系人里面 linkman1.setCustomer(customer1); // 3.提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); // sessionFactory.close(); } } }
(2)HibernateManytoMany.java
package hibernatetest; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.manytomany.Role; import cn.itcast.manytomany.User; import cn.itcast.utils.HibernateUtils; public class HibernateManytoMany { // 演示维护第三张表 @Test public void testTable1() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 让某个用户拥有某个角色 // 1.查询 User user1 = session.get(User.class, 2); Role role1 = session.get(Role.class, 2); // 2.放 user1.getSetRole().add(role1); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); // sessionFactory.close(); } } // 演示:维护第三张表 @Test public void testTable2() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 让某个用户没有某个角色 User user2 = session.get(User.class, 2); Role role2 = session.get(Role.class, 3); // 从用户里面把角色去掉 user2.getSetRole().remove(role2); // 提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); // sessionFactory.close(); } } // 演示:多对多级联删除 @Test public void testSave() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 添加两个用户,为每个用户相加两个角色 // 1.创建对象 User user3 = new User(); user3.setUser_name("春花"); user3.setUser_password("8766899"); User user4 = new User(); user4.setUser_name("mary"); user4.setUser_password("456"); Role role3 = new Role(); role3.setRole_name("pig"); role3.setRole_memo("粉色的"); Role role4 = new Role(); role4.setRole_name("秘书"); role4.setRole_memo("秘书"); Role role5 = new Role(); role5.setRole_name("保安"); role5.setRole_memo("保安"); // 2.建立关系,把角色放到用户里面 user3.getSetRole().add(role3); user3.getSetRole().add(role4); user4.getSetRole().add(role4); user4.getSetRole().add(role5); // 3.保存 session.save(user3); session.save(user4); // 4.提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); // sessionFactory.close(); } } // 演示:多对多级联保存 @Test public void testDelete() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); User user5 = session.get(User.class, 1); session.delete(user5); // 提交事务 tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); // sessionFactory.close(); } } }
5.cn.itcast.manytomany包
(1)Role.java
package cn.itcast.manytomany; import java.util.HashSet; import java.util.Set; public class Role { private Integer role_id; private String role_name; private String role_memo; // 一个角色有多个客户 private Set<User> setUser = new HashSet<User>(); public Set<User> getSetUser() { return setUser; } public void setSetUser(Set<User> setUser) { this.setUser = setUser; } public Integer getRole_id() { return role_id; } public void setRole_id(Integer role_id) { this.role_id = role_id; } public String getRole_name() { return role_name; } public void setRole_name(String role_name) { this.role_name = role_name; } public String getRole_memo() { return role_memo; } public void setRole_memo(String role_memo) { this.role_memo = role_memo; } }
Role.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" > <hibernate-mapping> <!-- 1.配置类和表对应 class标签 name属性:实体类的全路径 table属性:数据库表名称 --> <class name="cn.itcast.manytomany.Role" table="t_role"> <id name="role_id" column="role_id"> <generator class="native"></generator> </id> <property name="role_name" column="role_name"></property> <property name="role_memo" column="role_memo"></property> <!-- 在角色里面表示所有用户,使用set标签 --> <set name="setUser" table="user_role"> <!-- 角色在第三张表外键 --> <key column="roleid"></key> <many-to-many class="cn.itcast.manytomany.User" column="userid"></many-to-many> </set> </class> </hibernate-mapping>
(2)User.java
package cn.itcast.manytomany; import java.util.HashSet; import java.util.Set; public class User { private Integer user_id; private String user_name; private String user_password; // 一个用户可以有多个角色 private Set<Role> setRole = new HashSet<Role>(); public Set<Role> getSetRole() { return setRole; } public void setSetRole(Set<Role> setRole) { this.setRole = setRole; } public Integer getUser_id() { return user_id; } public void setUser_id(Integer user_id) { this.user_id = user_id; } public String getUser_name() { return user_name; } public void setUser_name(String user_name) { this.user_name = user_name; } public String getUser_password() { return user_password; } public void setUser_password(String user_password) { this.user_password = user_password; } }
User.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" > <hibernate-mapping> <class name="cn.itcast.manytomany.User" table="t_user"> <id name="user_id" column="user_id"> <generator class="native"></generator> </id> <property name="user_name" column="user_name"></property> <property name="user_password" column="user_password"></property> <!-- 在用户里面表示所有角色,使用set标签 name属性:角色set集合名称 table属性:第三张表名称 --> <set name="setRole" table="user_role" cascade="save-update,delete"> <!-- key标签里面的配置 配置当前映射文件在第三张表外键的名称 --> <key column="userid"></key> <!-- class标签:角色实体类的全路径 column标签:角色在第三张表外键名称 --> <many-to-many class="cn.itcast.manytomany.Role" column="roleid"></many-to-many> </set> </class> </hibernate-mapping>
第四篇:HQL、QBC 、查询、检索策略、批量抓取等 相关练习篇
1.cn.itcast.entity包
(1)Cutomer.java
package cn.itcast.entity; import java.util.HashSet; import java.util.Set; public class Customer { private Integer cid; private String custName; private String custLevel; private String custSource; private String custPhone; private String custMobile; // 在客户实体类里面表示多个联系人,一个客户有多个联系人 private Set<LinkMan> setLinkMan = new HashSet<LinkMan>(); public Set<LinkMan> getSetLinkMan() { return setLinkMan; } public void setSetLinkMan(Set<LinkMan> setLinkMan) { this.setLinkMan = setLinkMan; } public Integer getCid() { return cid; } public void setCid(Integer cid) { this.cid = cid; } public String getCustName() { return custName; } public void setCustName(String custName) { this.custName = custName; } public String getCustLevel() { return custLevel; } public void setCustLevel(String custLevel) { this.custLevel = custLevel; } public String getCustSource() { return custSource; } public void setCustSource(String custSource) { this.custSource = custSource; } public String getCustPhone() { return custPhone; } public void setCustPhone(String custPhone) { this.custPhone = custPhone; } public String getCustMobile() { return custMobile; } public void setCustMobile(String custMobile) { this.custMobile = custMobile; } }
Customer.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="cn.itcast.entity.Customer" table="t_customer"> <id name="cid" column="cid"> <generator class="native"></generator> </id> <property name="custName" column="custName"></property> <property name="custLevel" column="custLevel"></property> <property name="custSource" column="custSource"></property> <property name="custPhone" column="custPhone"></property> <property name="custMobile" column="custMobile"></property> <!-- 在客户映射文件中,表示所有联系人 使用set标签表示所有联系人 set标签里面有name属性: 属性值写在客户实体类里面表示联系人的set集合名称 inverse属性默认值:false不放弃关系维护 true表示放弃关系维护 --> <set name="setLinkMan" batch-size="10"> <!-- 一对多建表,有外键 hibernate机制:双向维护外键,在一和多那一方都配置外键 column属性值:外键名称 --> <key column="clid"></key> <one-to-many class="cn.itcast.entity.LinkMan"/> </set> </class> </hibernate-mapping>
(2).LinkMan.java
package cn.itcast.entity; public class LinkMan { private Integer lkm_id; // 联系人编号(主键) private String lkm_name;// 联系人姓名 private String lkm_gender;// 联系人性别 private String lkm_phone;// 联系人办公电话 // 在联系人实体类中表示所属客户,一个联系人只能有一个客户 private Customer customer; public Customer getCustomer() { return customer; } public void setCustomer(Customer customer) { this.customer = customer; } public Integer getLkm_id() { return lkm_id; } public void setLkm_id(Integer lkm_id) { this.lkm_id = lkm_id; } public String getLkm_name() { return lkm_name; } public void setLkm_name(String lkm_name) { this.lkm_name = lkm_name; } public String getLkm_gender() { return lkm_gender; } public void setLkm_gender(String lkm_gender) { this.lkm_gender = lkm_gender; } public String getLkm_phone() { return lkm_phone; } public void setLkm_phone(String lkm_phone) { this.lkm_phone = lkm_phone; } }
LinkMan.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="cn.itcast.entity.LinkMan" table="t_linkman"> <id name="lkm_id" column="lkm_id"> <generator class="native"></generator> </id> <property name="lkm_name" column="lkm_name"></property> <property name="lkm_gender" column="lkm_gender"></property> <property name="lkm_phone" column="lkm_phone"></property> <!-- 表示联系人所属客户 name属性:因为在联系人实体类使用customer对象表示,写customer名称 class属性:customer全路径 column属性:外键名称 --> <many-to-one name="customer" class="cn.itcast.entity.Customer" column="clid"></many-to-one> </class> </hibernate-mapping>
2.utils包(同上)
HibernateUtils.java
package ustils; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtils { static Configuration cfg = null; static SessionFactory sessionFactory = null; static { cfg = new Configuration(); cfg.configure(); sessionFactory = cfg.buildSessionFactory(); } public static Session getSessionobject() { return sessionFactory.getCurrentSession(); } public static SessionFactory getSessionFactory() { return sessionFactory; } public static void main(String[] args) { } }
3.Hibernate核心配置文件
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql:///hibernate_test4</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <property name="hibernate.show_sql">true</property> <property name="hibernate.format_sql">true</property> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.current_session_context_class">thread</property> <mapping resource="cn/itcast/entity/Customer.hbm.xml"/> <mapping resource="cn/itcast/entity/LinkMan.hbm.xml"/> </session-factory> </hibernate-configuration>
4.cn.itcast.hibernantetest包
(1)HibernateDemo.java
package cn.itcast.hibernantetest; import java.util.List; import java.util.Set; import org.hibernate.Criteria; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.Customer; import cn.itcast.entity.LinkMan; import ustils.HibernateUtils; public class HibernateDemo { // 演示对象导航查询 @Test public void testSelect1() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.查询cid=1客户 Customer customer = session.get(Customer.class, 1); // 2.再查询这个客户里面的所有联系人(此时,得到set集合,没有发送语句) Set<LinkMan> linkman = customer.getSetLinkMan(); // 发送了语句 System.out.println(linkman.size()); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示检索策略 @Test public void testSelect2() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 根据cid=1客户 // 执行get方法之后是否发送sql语句 // 调用get方法马上发送sql语句查询数据库 // Customer customer = session.get(Customer.class, 1); // System.out.println(customer.getCid()); /* * 1 调用load方法之后,不会马上发送sql语句 (1)返回对象里面只有 id值 * * 2 得到对象里面不是id的其他值时候才会发送语句 */ Customer customer = session.load(Customer.class, 1); System.out.println(customer.getCid()); System.out.println(customer.getCustName()); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示批量抓取 @Test public void testSelect3() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 查询所有客户 Criteria criteria = session.createCriteria(Customer.class); // 得到每个客户里面所有的联系人 List<Customer> list = criteria.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); // 每个客户里面的所有联系人 Set<LinkMan> setlinkman = customer.getSetLinkMan(); for (LinkMan linkMan : setlinkman) { System.out.println((linkMan.getLkm_id() + "::" + linkMan.getLkm_name())); } } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } }
(2)HibernateHQL.java
package cn.itcast.hibernantetest; import java.util.List; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.entity.Customer; import ustils.HibernateUtils; public class HibernateHQL { // 演示查询所有 @Test public void testSelect1() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 Query query = session.createQuery("from Customer"); // 2.调用方法得到结果 List<Customer> list = query.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示条件查询 @Test public void testSelect2() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 // SELECT *FROM t_customer WHERE cid=? AND custName=? Query query = session.createQuery("from Customer c where c.cid=? and c.custName=?"); // 2.设置条件 // 向?里面设置值 // setParameter方法两个参数 // 第一个参数:int类型是?位置,?位置从0开始 // 第二个参数:具体参数值 // 设置第一个?值 query.setParameter(0, 1); // 设置第二个?值 query.setParameter(1, "百度"); // 3.调用方法得到结果 List<Customer> list = query.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示条件查询-模糊查询 @Test public void testSelect3() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 Query query = session.createQuery("from Customer c where c.custName like ?"); // 2.设置?的值 query.setParameter(0, "%蒂%"); // 3.调用方法得到结果 List<Customer> list = query.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:排序查询 @Test public void testSelect4() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 Query query = session.createQuery("from Customer order by cid desc"); // 2.调用方法得到结果 List<Customer> list = query.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:分页查询 @Test public void testSelect5() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 // 写查询所有的语句 Query query = session.createQuery("from Customer"); // 2.设置分页数据 // 2.1.设置开始位置 query.setFirstResult(3); // 2.2.设置每页记录数 query.setMaxResults(3); // 3.调用方法得到结果 List<Customer> list = query.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:投影查询 @Test public void testSelect6() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 Query query = session.createQuery("select custLevel from Customer"); // 2.调用方法得到结果 List<Object> list = query.list(); for (Object object : list) { System.out.println(object); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:聚集函数的使用 @Test public void testSelect7() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建query对象 Query query = session.createQuery("select count(*) from Customer"); // 2.调用方法得到结果 // query对象里面有方法,直接返回对象形式 Object obj = query.uniqueResult(); // 返回int类型 // int count=(int)obj; // 首先把object变成long类型,再变成int类型 Long lobj = (Long) obj; int count = lobj.intValue(); System.out.println(count); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } }
(3)HibernateQBC.java
package cn.itcast.hibernantetest; import java.util.List; import org.hibernate.Criteria; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.criterion.DetachedCriteria; import org.hibernate.criterion.Order; import org.hibernate.criterion.Projections; import org.hibernate.criterion.Restrictions; import org.junit.Test; import cn.itcast.entity.Customer; import ustils.HibernateUtils; public class HibernateQBC { // 演示:查询所有 @Test public void testSelect1() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建对象 Criteria criteria = session.createCriteria(Customer.class); // 2.调用方法得到结果 List<Customer> list = criteria.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:条件查询 @Test public void testSelect2() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建criteria对象 Criteria criteria = session.createCriteria(Customer.class); // 2.使用criteria对象里面的方法设置条件值 // 首先使用add方法,表示设置条件值 // 在add方法里面使用类的方法实现条件设置 // 类似于cid=? // criteria.add(Restrictions.eq("cid", 1)); // criteria.add(Restrictions.eq("custName", "玛莎拉蒂")); // 上面是eq,下面是like criteria.add(Restrictions.like("custName", "%百%")); // 3.调用方法得到结果 List<Customer> list = criteria.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:排序查询 @Test public void testSelect3() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建对象 Criteria criteria = session.createCriteria(Customer.class); // 2.设置对哪个属性进行排序,设置排序规则 criteria.addOrder(Order.desc("cid")); // 3.调用方法,得到结果 List<Customer> list = criteria.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:分页查询 @Test public void testSelect4() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建对象 Criteria criteria = session.createCriteria(Customer.class); // 2.设置分页,起始和记录数 criteria.setFirstResult(3); criteria.setMaxResults(3); // 3.调用方法得到结果 List<Customer> list = criteria.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:统计查询 @Test public void testSelect5() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建对象 Criteria criteria = session.createCriteria(Customer.class); // 2.设置操作 criteria.setProjection(Projections.rowCount()); // 3.调用方法得到结果 Object obj = criteria.uniqueResult(); Long lobj = (Long) obj; int count = lobj.intValue(); System.out.println(count); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示:离线查询 @Test public void testSelect6() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 1.创建对象 // Criteria criteria = session.createCriteria(Customer.class); DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Customer.class); // 2.最终执行时候才需要得到session Criteria criteria = detachedCriteria.getExecutableCriteria(session); List<Customer> list = criteria.list(); for (Customer customer : list) { System.out.println(customer.getCid() + "::" + customer.getCustName()); } tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } }
(4)HibernateManyTable.java
package cn.itcast.hibernantetest; import java.util.List; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.junit.Test; import ustils.HibernateUtils; public class HibernateManyTable { // 演示hql内连接查询(2种) @Test public void testSelect1() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 内连接的list返回的是数组的形式;迫切内外连接的list放回的是对象的形式 // Query query = session.createQuery("from Customer c inner join // c.setLinkMan"); // List list = query.list(); Query query = session.createQuery("from Customer c inner join fetch c.setLinkMan"); List list = query.list(); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } // 演示hql外连接查询(3种) @Test public void testSelect2() { SessionFactory sessionFactory = null; Session session = null; Transaction tx = null; try { sessionFactory = HibernateUtils.getSessionFactory(); session = sessionFactory.openSession(); tx = session.beginTransaction(); // 左外连接的list返回的是数组的形式;迫切左外连接的list放回的是对象的形式 // Query query = session.createQuery("from Customer c left outer // join c.setLinkMan"); // List list = query.list(); // Query query = session.createQuery("from Customer c left outer // join fetch c.setLinkMan"); // List list = query.list(); // 右外连接,没有迫切右外连接 Query query = session.createQuery("from Customer c right outer join fetch c.setLinkMan"); List list = query.list(); tx.commit(); } catch (Exception e) { e.printStackTrace(); tx.rollback(); } finally { session.close(); sessionFactory.close(); } } }
Hibernate定义陈述:
Hibernate是一个开放源代码的对象关系映射框架,它对JDBC进行了非常轻量级的对象封装,它将POJO与数据库表建立映射关系,是一个全自动的orm框架,hibernate可以自动生成SQL语句,自动执行,使得Java程序员可以随心所欲的使用对象编程思维来操纵数据库。 Hibernate可以应用在任何使用JDBC的场合,既可以在Java的客户端程序使用,也可以在Servlet/JSP的Web应用中使用,最具革命意义的是,Hibernate可以在应用EJB的JaveEE架构中取代CMP,完成数据持久化的重任。-------来自百度百科
原文链接:https://www.cnblogs.com/1693977889zz/p/13069802.html
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