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session
public static Session getSession () {
Session session = sessionFactory.openSession ();
return session;
}
//关闭session
public 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>