HQL(Hibernate Query Language)

1:HQL（Hibernate Query Language）：面向的是对象而不是数据库中的表，

这是与SQL（Structured Query Language）之间的差别

2:Session的get与load方法都可以获取相应的持久化对象，如果该对象存在，那么这二个方法的

行为是一样的；如果改对象不存在，那么get方法会返回null而load方法会抛出异常。

2:用hibernate实现一张表的增删改查

hibernate整合struts2的员工增删改查

dao包：

package dao;import java.util.List;import model.Person;public interface PersonDao {public void savePerson (Person person);public List<Person> listAllPersons();public void removePerson (String id);public Person getSinglePersonById(String id);public void updatePerson (Person person);}

dao.impl包：

package dao.impl;import java.util.List;import org.hibernate.Query;import org.hibernate.Session;import org.hibernate.Transaction;import util.HibernateUtil;import model.Person;import dao.PersonDao;public class PersonDaoImpl implements PersonDao {public void savePerson(Person person) {Session session = HibernateUtil.getSession();/** * */Transaction tx = session.beginTransaction();try {session.save(person);tx.commit();}catch(Exception ex){ex.printStackTrace();if (null != tx) {tx.rollback();}}finally{HibernateUtil.close(session);}}@SuppressWarnings("unchecked")public List<Person> listAllPersons() {List<Person> persons = null;Session session = HibernateUtil.getSession();Transaction tx = session.beginTransaction();try {//Person是类的名字而不是表的名字，既然是类的名字就需要严格区分大小写Query query = session.createQuery("from Person");//类的名字persons = (List<Person>)query.list();tx.commit();}catch (Exception ex) {if (tx != null) {tx.rollback();}}finally {HibernateUtil.close(session);}return persons;}public void removePerson(String id) {Session session = HibernateUtil.getSession();Transaction tx = session.beginTransaction();try {Person person = (Person)session.get(Person.class, id);session.delete(person);tx.commit();}catch(Exception ex) {ex.printStackTrace();if (null != tx) {tx.rollback();}}finally {HibernateUtil.close(session);}}public Person getSinglePersonById(String id) {Session session = HibernateUtil.getSession();Transaction tx = session.beginTransaction();Person person = null;try {person = (Person)session.get(Person.class, id);}catch(Exception ex) {ex.printStackTrace();if (null != tx) {tx.rollback();}}finally{HibernateUtil.close(session);}return person;}public void updatePerson(Person person) {Session session = HibernateUtil.getSession();Transaction tx = session.beginTransaction();try {session.update(person);tx.commit();}catch(Exception ex) {ex.printStackTrace();if (null != tx) {tx.rollback();}}finally{HibernateUtil.close(session);}}}

util包：

package util;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;public class HibernateUtil {private static SessionFactory sessionFactory;/** * ***/static {try {sessionFactory  = new Configuration().configure().buildSessionFactory();}catch(Exception e) {}}//获得sessionpublic static Session getSession () {Session session =  sessionFactory.openSession ();return session;}//关闭sessionpublic static void close (Session session) {if (null != session) {session.close();}}}

service包：

package service;import java.util.List;import model.Person;public interface PersonService {public void savePerson (Person person);public List<Person> listAllPersons ();public void removePerson (String id);public Person getSinglePersonById(String id);public void updatePerson (Person person);}

service.impl包：

package service.imp;import java.util.List;import service.PersonService;import dao.PersonDao;import dao.impl.PersonDaoImpl;import model.Person;public class PersonServieImpl implements PersonService{public void savePerson (Person person) {PersonDao pd = new PersonDaoImpl();pd.savePerson(person);}public List<Person> listAllPersons() {PersonDao pd = new PersonDaoImpl();return pd.listAllPersons();}public void removePerson(String id) {PersonDao pd = new PersonDaoImpl();pd.removePerson(id);}public Person getSinglePersonById(String id) {PersonDao pd = new PersonDaoImpl();return pd.getSinglePersonById(id);}public void updatePerson(Person person) {PersonDao pd = new PersonDaoImpl ();pd.updatePerson(person);}}

action.person包中：

package action.person;import java.util.List;import javax.servlet.http.HttpServletRequest;import org.apache.struts2.ServletActionContext;import service.PersonService;import service.imp.PersonServieImpl;import model.Person;import com.opensymphony.xwork2.Action;import com.opensymphony.xwork2.ActionSupport;@SuppressWarnings("serial")public class PersonAction extends ActionSupport{private String id;private String username;private String password;private int age;private java.sql.Date registerDate;public java.sql.Date getRegisterDate() {return registerDate;}public void setRegisterDate(java.sql.Date registerDate) {this.registerDate = registerDate;}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 int getAge() {return age;}public void setAge(int age) {this.age = age;}public String listAllPerson () throws Exception {PersonService personService = new PersonServieImpl();List<Person> list = personService.listAllPersons();HttpServletRequest request = ServletActionContext.getRequest();request.setAttribute("list", list);return Action.SUCCESS;}public String savePerson () throws Exception {Person person = new Person ();person.setUsername(username);person.setPassword(password);person.setAge(age);java.sql.Date registerDate = new java.sql.Date(new java.util.Date().getTime());person.setRegisterDate(registerDate);PersonService personService = new PersonServieImpl();personService.savePerson(person);return Action.SUCCESS;}public String deletePerson ()throws Exception {PersonService personService = new PersonServieImpl();personService.removePerson(id);return Action.SUCCESS;}public String getSinglePerson () throws Exception{PersonService personService = new PersonServieImpl ();Person person = personService.getSinglePersonById(id);HttpServletRequest request = ServletActionContext.getRequest();request.setAttribute("person", person);return "success";}public String updatePerson () throws Exception {PersonService personService = new PersonServieImpl ();Person person = new Person ();person.setId(id);person.setAge(age);person.setPassword(password);person.setRegisterDate(registerDate);person.setUsername(username);personService.updatePerson(person);return Action.SUCCESS;}public String getId() {return id;}public void setId(String id) {this.id = id;}}

hibernate.cfg.xml主配置文件：

<?xml version='1.0' encoding='UTF-8'?><!DOCTYPE hibernate-configuration PUBLIC          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">          <hibernate-configuration>    <session-factory>    <property name="connection.url">jdbc:mysql://localhost:3306/hibernate</property>    <property name = "connection.username">root</property>    <property name = "connection.password">baother520</property>    <property name = "connection.driver_class">com.mysql.jdbc.Driver</property>    <property name = "dialect">org.hibernate.dialect.MySQL5Dialect</property>    <property name = "show_sql">true</property>    <mapping resource="Person.hbm.xml" />    </session-factory></hibernate-configuration>

Person.hbm.xml映射文件:

<?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 = "model.Person" table = "person"><id name = "id" column = "id" type = "string"><generator class="uuid"></generator></id><property name = "username" column = "username" type = "string"></property><property name="age" column = "age" type = "int"></property><property name = "registerDate" column = "registerDate" type = "date"></property></class></hibernate-mapping>