针对版本hibernate-distribution-3.6.0.Final的学习
搭建环境及开发步骤
-
引入jar包
- hibernate3.jar核心
- required 必须引入的(6个)
- antlr-2.7.6.jar
- commons-collections-3.1.jar
- dom4j-1.6.1.jar
- javassist-3.12.0.GA.jar
- jta-1.1.jar
- slf4j-api-1.6.1.jar
- jpa 目录
- hibernate-jpa-2.0-api-1.0.0.Final.jar
- 数据库驱动包
- mysql-connector-java-5.1.7-bin.jar
-
写对象以及对象的映射
- Employee.java 对象
- Employee.hbm.xml 对象的映射 (映射文件)
public class Employee {
private int empId;
private String empName;
private Date workDate;
public int getEmpId(){
return empId;
}
public void setEmpId(int empId){
this.empId = empId;
}
public String getEmpName(){
return empName;
}
public void setEmpName(String empName){
this.empName = empName;
}
public Date getWorkDate(){
return workDate;
}
public void setWorkDate(Date workDate){
this.workDate = workDate;
}
@Override
public String toString(){
return "Employee{" +
"empId=" + empId +
", empName='" + empName + '\'' +
", workDate=" + workDate +
'}';
}
}
Employee.hbm.xml文件 : 先确保数据库和表都已存在
create table employee (id int not null primary key auto_increment,empName varchar(10),workDate datetime);
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!-- Generated Nov 9, 2006 6:27:53 PM by Hibernate Tools 3.2.0.beta7 -->
<hibernate-mapping package="com.flynn">
<class name="Employee" table="employee" >
<!--主键-->
<id name="empId" column="id" type="java.lang.Integer">
<generator class="native"/>
</id>
<property name="empName" column="empName"></property>
<property name="workDate" column="workDate"></property>
</class>
</hibernate-mapping>
- src/hibernate.cfg.xml 主配置文件
- 数据库连接配置
- 加载所用的映射(*.hbm.xml)
<!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>
<!--数据库连接-->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://192.168.5.129:3306/partner</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">mysql</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
<property name="hibernate.show_sql">true</property>
<mapping resource="com/flynn/Employee.hbm.xml"></mapping>
</session-factory>
</hibernate-configuration>
4.App.java测试 : 一次简单的测试
public class App {
@Test
public void testSave() throws Exception{
Employee emp = new Employee();
emp.setEmpName("zhang");
emp.setWorkDate(new Date());
// 获取加载配置文件的管理类对象
Configuration config = new Configuration();
// 加载配置文件
config.configure();
SessionFactory sessionFactory = config.buildSessionFactory();
// 创建session
Session session = sessionFactory.openSession();
// 提交事务
Transaction tx = session.beginTransaction();
// --执行操作--
session.save(emp);
// 提交事务
tx.commit();
// 关闭session
session.close();
}
}
测试通过 :
testSave.png
Hibernate的Api
-
Configuration 配置管理类对象
- config.configure(); 加载主配置文件的方法(hibernate.cfg.xml) 默认加载src/hibernate.cfg.xml
- config.configure(“cn/config/hibernate.cfg.xml”); 加载指定路径下指定名称的主配置文件
- config.buildSessionFactory(); 创建session的工厂对象
-
SessionFactory session的工厂（或者说代表了这个hibernate.cfg.xml配置文件）
- sf.openSession(); 创建一个sesison对象
- sf.getCurrentSession(); 创建session或取出session对象
-
Session session对象维护了一个连接(Connection), 代表了与数据库连接的会话。
- Hibernate最重要的对象： 只用使用hibernate与数据库操作，都用到这个对象
- session.beginTransaction(); 开启一个事务；
hibernate要求所有的与数据库的操作必须有事务的环境，否则报错！
-
更新：
- session.save(obj); 保存一个对象
- session.update(emp); 更新一个对象
- session.saveOrUpdate(emp); 保存或者更新的方法：
- 没有设置主键，执行保存；
- 有设置主键，执行更新操作;
- 如果设置主键不存在报错！
-
主键查询：
- session.get(Employee.class, 1); 主键查询
- session.load(Employee.class, 1); 主键查询 (支持懒加载)
-
HQL查询
- HQL查询与SQL查询区别
- SQL:(结构化查询语句) 查询的是表以及字段 ; 不区分大小写
- HQL: hibernate query language 即hibernate提供的面向对象的查询语言
- 查询的是对象以及对象的属性
- 区分大小写
- HQL查询与SQL查询区别
/**
* HQL查询
* @throws Exception e
*/
@Test
public void testQuery() throws Exception{
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Query q = session.createQuery("from Employee");
// Query q = session.createQuery("from Employee where empId=1 or empId=2"); 带条件的查询
List<Employee> list = q.list();
System.out.println(list);
transaction.commit();
session.close();
}
- Criteria查询
- 完全面向对象的查询。
/**
* QBC查询 query by criteria 完全面向对象查询
* @throws Exception e
*/
@Test
public void testQBC() throws Exception{
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Criteria criteria = session.createCriteria(Employee.class);
// criteria.add(Restrictions.eq("empId",1)); 条件查询
List<Employee> list = criteria.list();
System.out.println(list);
transaction.commit();
session.close();
}
- 本地SQL查询
复杂的查询，就要使用原生态的sql查询，也可以，就是本地sql查询的支持！
(缺点： 不能跨数据库平台！)
/**
* sql查询
* @throws Exception 异常
*/
@Test
public void testSql() throws Exception{
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
// SQLQuery sqlQuery = session.createSQLQuery("select * from employee");
SQLQuery sqlQuery = session.createSQLQuery("select * from employee").addEntity(Employee.class);
System.out.println(sqlQuery.list());
transaction.commit();
}
CRUD案例
//仅随手测试代码 请忽略不够优化,也不要找我茬
public class HibernateUtils {
private static SessionFactory sf;
static {
// 加载主配置文件, 并创建Session的工厂
sf = new Configuration().configure().buildSessionFactory();
}
public static Session getSession(){
return sf.openSession();
}
}
public interface IEmployeeDao {
void save(Employee employee);
void update(Employee employee);
void delete(Serializable id);
Employee findById(Serializable id);
List<Employee> getAll();
List<Employee> getAll(String employeeName);
List<Employee> getAll(int pageNo, int pageSize);
}
public class EmployeeDaoImpl implements IEmployeeDao {
@Override
public void save(Employee employee){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
session.save(employee);
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
@Override
public void update(Employee employee){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
session.update(employee);
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
@Override
public void delete(Serializable id){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
Object obj = session.get(Employee.class, id);
if(obj != null){
session.delete(obj);
}
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
@Override
public Employee findById(Serializable id){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
return (Employee) session.get(Employee.class, id);
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
@Override
public List<Employee> getAll(){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
Query q = session.createQuery("from Employee");
return q.list();
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
@Override
public List<Employee> getAll(String employeeName){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
Query q = session.createQuery("from Employee where empName = ?");
// 注意: 参数索引从0开始
q.setParameter(0, employeeName);
return q.list();
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
@Override
public List<Employee> getAll(int pageNo, int pageSize){
Session session = null;
Transaction tx = null;
try{
session = HibernateUtils.getSession();
tx = session.beginTransaction();
Query query = session.createQuery("from Employee");
// 设置分页参数
query.setFirstResult(pageNo);
query.setMaxResults(pageSize);
List<Employee> list = query.list();
return list;
}catch(Exception e){
throw new RuntimeException(e);
}finally{
if(tx != null){
tx.commit();
}
if(session != null){
session.close();
}
}
}
}
