1.Habernate
a.定义：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（简单java对象，即javabean）与数据库表建立映射关系，是一个全自动的ORM框架
b.ORM：对象关系映射（Object Relation Mapping）
2.使用：
a.在SRC下建hibernate.cfg.xml
<?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/j116
</property>
<property name="connection.username">root</property>
<property name="connection.password">admin</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<mapping resource="com/wode/pojo/User.hbm.xml" />
</session-factory>
</hibernate-configuration>
b.建User的映射配置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="com.wode.pojo.User" table="users">
<id name="userId" column="user_id" type="integer">
<generator class="native"></generator>
</id>
<property name="userName" column="user_name" type="string"></property>
<property name="userPwd" column="user_pwd" type="string"></property>
<property name="userType" column="user_type" type="int"></property>
</class>
</hibernate-mapping>
c.使用
User u=new User();
u.setUserName("test");
u.setUserPwd("test");
u.setUserType(1);
Configuration cfg=new Configuration();
cfg.configure();//加载hibernateConfiguration
ServiceRegistry registry=new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();
SessionFactory factory=cfg.buildSessionFactory(registry);
Session session=factory.openSession();
Transaction tx=session.beginTransaction();
session.save(u);
tx.commit();
session.close();
3.增删查改
a.增
session.save(u);
b.删
session.delete(u); //需要设置User的Id
c.查
//方法一：hql
Query query = session.createQuery("from User");
List<User> list=query.list(); //方法二：sql
Query query =session.createSQLQuery("select * from users").addEntity(User.class);
List<User> list=query.list(); //方法三：单个对象
User u=(User) session.load(User.class, 1);//延迟加载
User u=(User) session.get(User.class, 1);
d.改
//方法一
User u = (User) session.get(User.class, 1);
u.setUserPwd("123456");
session.beginTransaction().commit(); //方法二（没set的属性将自动设为空，不建议使用）
User u = new User();
u.setUserId(1);
u.setUserPwd("123456");
session.update(u);
session.beginTransaction().commit();
4.查询拓展
a.分页查询
Query query = session.createQuery("from User");
//当前页
int currentPage = 1;
//一页多少条
int pageSize = 5;
query.setFirstResult((currentPage-1)*pageSize);
query.setMaxResults(pageSize);
List<User> list = query.list();
for(User u : list){
System.out.println(u.getUserName()+" "+u.getUserPwd());
}
b.聚合函数
Query query=session.createQuery("select count(*) from Course");
c.模糊查询
//Query query = session.createQuery("from User u where u.userName like ?");
//query.setString(0, "%z%");
Query query = session.createQuery("from User u where u.userName like :name");
query.setString("name", "%z%");
List<User> list = query.list();
d.不用session的方式
Query query=session.createQuery("delete Course c where c.courseName =wa ");
int =query.executeUpdate()
5.一对多
a.在Many方xml中配置
<many-to-one name="dept" class="com.wode.entity.Dept" column="deptNo" lazy="false" fetch="join"/>
b.在One方xml中配置
<set name="emps" lazy="false" fetch="join" cascade="all">
<key column="deptNo"></key>
<one-to-many class="com.wode.entity.Emp"/>
</set>
c.级联添加
Dept dept = new Dept();
dept.setDeptNo(40);
dept.setDname("销售部");
dept.setLoc("红瓦寺"); Emp emp = new Emp();
emp.setEmpno(9527);
emp.setEname("若湖");
...
emp.setDept(dept); Emp emp2 = new Emp();
emp2.setEmpno(9528);
emp2.setEname("江瑕");
...
emp2.setDept(dept); Set<Emp> emps = new HashSet<Emp>();
emps.add(emp);
emps.add(emp2);
dept.setEmps(emps); session.save(dept);
session.beginTransaction().commit();
d.级联删除
Dept dept = (Dept) session.get(Dept.class, 40);
session.delete(dept);
session.beginTransaction().commit();
e.通过Dept删除某个Emp
Dept dept = (Dept) session.get(Dept.class, 40);
Set<Emp> emps = dept.getEmps();
Iterator<Emp> it = emps.iterator();
while(it.hasNext()){
if(it.next().getEname().equals("江瑕")){
it.remove();
}
}
session.beginTransaction().commit();
f.查找所有的Dept以及所有Dept里面的Emp
List<Dept> depts = session.createQuery("select distinct(d) from Dept d join fetch d.emps").list();
for(Dept dept : depts){
System.out.println(dept.getDname());
for(Emp emp : dept.getEmps()){
System.out.println(emp.getEname());
}
}
6.多对多
a.配置xml
<set name="courses" table="t_s_fk">
<key column="sId"></key>
<many-to-many class="Course" column="cId"></many-to-many>
</set>
b.添加（近增加相互之间的关系）
Student stu = (Student) session.get(Student.class, 3);
Course course1 = (Course) session.get(Course.class, 1);
Course course2 = (Course) session.get(Course.class, 3); stu.getCourses().add(course1);
stu.getCourses().add(course2); session.beginTransaction().commit();
c.通过科目名称查找选了这门课程的学生
Course course = (Course) session.get(Course.class, 1);
Set<Student> stus = course.getStus();
for(Student stu : stus){
System.out.println(stu.getStuName());
}
7.注解方式
a.将 <mapping resource="com/wode/pojo/Emp.hbm.xml" /> 改为 <mapping class="com.wode.pojo.Emp" />
b.标注方法参考Spring Data JPA
8.二级缓存
a.在src下创建ehcache.xml
b.在hibernate.cfg.xml中配置
<property name="cache.use_second_level_cache">true</property>
<property name="cache.use_query_cache">true</property>
<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
c. 在Bean的映射配置xml中配置
<cache usage="read-only" region="sampleCache1"/>
d.若使用的是注解则加@注解
@Cache(usage = CacheConcurrencyStrategy.READ_ONLY)
9.Habernate在Spring中的使用
a.在web.xml及applicationContext.xml中配置相应配置
b.使用：
@Autowired
@Qualifier("sessionFactory")
private SessionFactory sessionFactory; @Override
public void addUser(User user) {
// TODO Auto-generated method stub
Session session = sessionFactory.getCurrentSession();
session.save(user);
}