Hibernate如何使用

这篇文章主要介绍Hibernate如何使用，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！

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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

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