hibernate的来源
数据在各个层次之间流转，在流转过程中会发生数据类型转换等一系列的交互问题。java与html的交互解决方案是struts2提供的OGNL(对象导航图语言)，而java与数据库之间的技术解决方案是ORM(对象关系映射)。
什么是ORM
对象关系映射：Object relation mapping
1.对象：指的是java对象，是实体bean
2.关系：关系只是数据库，sqlserver，mysql，oracle属于关系型数据库，操作关系型数据库用的是sql语言，但是sql有着明显的缺点，一次只能执行一条语句，没有什么基本的逻辑判断
3.映射：java中对象的属性与数据库中的表字段之间一一对应(包含一对一，一对多，多对一，多对多)。
ORM需要满足的条件
有类属性和·表字段一一映射的关系
将关系模型(数据库)的操作转化成对对象模型(pojo)的操作
hibernate的优缺点
好处：不要程序自己编写sql，简化了开发，提高了开发速度，hibernate入门门槛低，上手快。
缺点：由hibernate自动生成的sql是标准的sql，优化难度大，失去了灵活性，对程序员要求较高，要懂一定的O/R映射。
快速入手hibernate案列(maven)
在pom.xml中导入相关的jar’包
org.hibernate
hibernate-core
3.6.5.Final
如果不能正常创建则需要导入其他包
<--hibenate核心包-->
org.hibernate
hibernate-core
3.6.8.Final
<--单元测试包(可不导入)-->
junit
junit
4.7
test
<-- Javassit其实就是一个二方包，提供了运行时操作Java字节码的方法-->
org.javassist
javassist
3.13.0-GA
<-- 并发访问处理端口的工具包。-->
backport-util-concurrent
backport-util-concurrent
2.2
<-- 日志文件包-->
commons-logging
commons-logging
1.1.1
<--纯Java的进程内缓存框架-->
net.sf.ehcache
ehcache
1.2.3
hibernate.cfg.xml配置文件
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
oracle.jdbc.driver.OracleDriver
jdbc:oracle:thin:@localhost:1521:orcl
scott
tiger
none
org.hibernate.dialect.Oracle10gDialect
thread
true
3.*.xml映射文件
先写一个实体bean
package com.it.bean;
public class Student {
private String stu_id;
private String stu_name;
private String stu_sex;
private String stu_birth;
private String stu_addr;
public String getStu_id() {
return stu_id;
}
public void setStu_id(String stu_id) {
this.stu_id = stu_id;
}
public String getStu_name() {
return stu_name;
}
public void setStu_name(String stu_name) {
this.stu_name = stu_name;
}
public String getStu_sex() {
return stu_sex;
}
public void setStu_sex(String stu_sex) {
this.stu_sex = stu_sex;
}
public String getStu_birth() {
return stu_birth;
}
public void setStu_birth(String stu_birth) {
this.stu_birth = stu_birth;
}
public String getStu_addr() {
return stu_addr;
}
public void setStu_addr(String stu_addr) {
this.stu_addr = stu_addr;
}
public Student(String stu_id, String stu_name, String stu_sex, String stu_birth, String stu_addr) {
super();
this.stu_id = stu_id;
this.stu_name = stu_name;
this.stu_sex = stu_sex;
this.stu_birth = stu_birth;
this.stu_addr = stu_addr;
}
public Student() {
super();
// TODO Auto-generated constructor stub
}
public Student(String stu_id, String stu_name) {
super();
this.stu_id = stu_id;
this.stu_name = stu_name;
}
}
与之对应的映射文件
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
dao层的书写
BaseDao
package com.it.dao;
import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;
public class BaseDao{
private Session session;
public BaseDao(Session session){
this.session=session;
}
public void add(E e){
session.save(e);
}
public void delete(E e){
session.delete(e);
}
public void update(E e){
session.update(e);
}
public List finbBySplit(int currentPage,int currentSize,String hql,String...params){
Query query=session.createQuery(hql);
//给问号占位符赋值
for (int i = 0; i < params.length; i++) {
query.setString(i, params[i]);
}
//分页参数
int first=(currentPage-1)*currentSize;
query.setFirstResult(first);
query.setMaxResults(currentSize);
//查询
return query.list();
}
}
StudentDao层的书写
package com.it.dao;
import java.util.List;
import org.hibernate.Session;
import com.it.bean.Student;
public class StudentDao extends BaseDao{
public StudentDao(Session session) {
super(session);
// TODO Auto-generated constructor stub
}
public void add(Student stu){
super.add(stu);
}
public void delete(Student stu){
super.delete(stu);
}
public void update(Student stu){
super.update(stu);
}
public List find(int currentPage,int currentSize,Student stu){
String hql="from Student stu where stu.stu_id like ? and stu.stu_name like ? and stu.stu_sex like ? and stu.stu_birth like ? and stu.stu_addr like ? ";
String []params={"%"+stu.getStu_id()+"%","%"+stu.getStu_name()+"%","%"+stu.getStu_sex()+"%","%"+stu.getStu_birth()+"%","%"+stu.getStu_addr()+"%"};
return super.finbBySplit(currentPage, currentSize, hql, params);
}
}
此时便可测试了
@Test
public void add(){
SessionFactory sessionFactory=null;
Session session=null;
Transaction tx=null;
try {
//创建sessionfactory
sessionFactory=new Configuration().configure().buildSessionFactory();
//创建session回话---得到线程本身的回话
session=sessionFactory.getCurrentSession();
//开启事务
tx=session.beginTransaction();
//添加数据
Student stu=new Student("0000","沈浪","男","87","北京");
// session.save(stu);
//修改数据
// stu.setStu_name("沈万三");
// session.update(stu);
//删除数据
// session.delete(stu);
//提交事务
//按照id查询一条数据
// Student stu1=(Student)session.get(Student.class, "0000");
// System.out.println(stu1.getStu_name());
//hql的使用
//查询所有信息
/*String hql="from Student where stu_id like '%2%'";
Query query=session.createQuery(hql);
List list=query.list();
for (Student student : list) {
System.out.println(student.getStu_name());
}*/无锡×××医院 https://yyk.familydoctor.com.cn/20612/
//返回vo对象
/*String hql="select new Student(stu_id,stu_name) from Student where stu_id like '%2%'";
Query query=session.createQuery(hql);
List list=query.list();
for (Student student : list) {
System.out.println(student.getStu_name());
}*/
//返回map类型的参数
/*String hql="select new map(count(*) as ct,max(stu_id) as maxid) from Student";
Query query=session.createQuery(hql);
Map map=(Map)query.uniqueResult();
System.out.println(map.get("ct"));*/
//占位符? :
/*String hql="from Student where stu_id like ?";
Query query=session.createQuery(hql);
query.setString(0, "%2%");
List list=query.list();
for (Student student : list) {
System.out.println(student.getStu_name()+"=========");
}*/
//:占位符
/*String hql="from Student where stu_sex=:uid";
Map params=new HashMap();
params.put("uid","1");
Query query=session.createQuery(hql);
//为参数赋值
for(String key:params.keySet()){
System.out.println(key+"==========");
query.setString(key,params.get(key));
}
List list=query.list();
for (Student student : list) {
System.out.println(student.getStu_name()+"+++++++");
}*/
//返回number类型的参数
/*String hql="select count(*) from Student";
Query query=session.createQuery(hql);
Number ct=(Number)query.uniqueResult();
System.out.println(ct.intValue());*/
//模糊搜素
/*Student stu1=new Student("1","武");
String[] params={"%"+stu1.getStu_id()+"%","%"+stu1.getStu_name()+"%"};
String hql="from Student where stu_id like ? and stu_name like ?";
// String hql="from Student where stu_id like '%1%' and stu_name like '%武%'";
Query query=session.createQuery(hql);
//为?号赋值
for (int i = 0; i < params.length; i++) {
query.setString(i,params[i]);
System.out.println(params[i]);
}
System.out.println(hql);
System.out.println(query.list().size());*/
//hibernate分页
String hql="from Student where stu_id like '%2%'";
Query query=session.createQuery(hql);
int currentPage=1;
int pageSize=4;
int startPage=(currentPage-1)*pageSize;
query.setFirstResult(startPage); //开始显示的位置
query.setMaxResults(pageSize); //显示最大数据数
System.out.println(query.list().size());
tx.commit();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
//事务回滚
tx.rollback();
}
}
此刻一个简单的demo变创建成功了