Hibernate 学习与使用

java无忧网 · 发表于 2016-5-28 17:38:27

**************第一章************

Hibernate是一个优秀的持久化框架

什么是持久化？

只有数据保存到数据库中这个对象才称为持久化对象

瞬时状态：保存在内存的程序数据，程序退出后，数据就消失了，称为瞬时状态

持久化：将程序数据在瞬时状态和持久状态之间转换的机制

持久状态：
保存在磁盘上的程序数据，程序退出后依然存在，称为程序数据的持久状态

什么是ORM？

ORM（对象-关系映射）：

完成对象数据到关系型数据映射的机制称为对象-关系映射，简称ORM。

是一个主流的持久化框架

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC46.tmp.png 在JDBC基础上进行分装

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC56.tmp.png 只需要少量代码就可以完成持久化工作

是一个优秀的ORM（对象-关系映射）机制

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC57.tmp.png 通过映射文件保存映射信息

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC58.tmp.png 在业务层以面向对象的方式编程，不用考虑数据保存形式

手工搭建Hibernate框架:

1.导包

最少依赖的jar包)

l 下载地址http://www.hibernate.org，本教程使用3.2.5。

l 将下载目录/hibernate3.jar和/lib下的hibernate运行时必须的包加入classpath中：

antlr.jar,cglib.jar,asm.jar,commons-collections.jar,commons-logging.jar,jta.jar,dom4j.jar

2.添加Hibernate配置文件 hibernate.cfg.xml(模板源代码/etc下)

打开源代码下 etc/ hibernate.cfg.xml 复制到 src路劲下

(注意：默认hibernate会在src下读取名称为hibernate.cfg.xml文件,这与Ibatis中SqlMapConfig.xml文件一样，主要配置数据库连接方式，打开数据库连接)

<property name="dialect"> //表示数据库方言不同数据库方言不同

org.hibernate.dialect.MySQL5Dialect

</property>

// 表示是否显示 sql语句

// 表示通过实体类映射创建数据库表 update/create

<property name="hbm2ddl.auto">update</property>

3.添加实体类(例如:User类)

com.hibernate.user.bean.User:

public class User {

private int uid;

private String userName;

private String password;

public int getUid() {

return uid;

}

public void setUid(int uid) {

this.uid = uid;

}

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;

}

4.实体类目录中添加 User.hbm.xml(模板在源代码eg\org\hibernate\auction)

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

<!-- generator 主键生成器

Increment 表示 mysql 主键并增长

Identity 表示 sqlserver 主键并增长

Sequence 表示 oracle 主键并增长

Native 表示兼容所有数据库由hibernate 判断

-->

</id>

</class>

</hibernate-mapping>

5. hibernate.cfg.xml文件中添加 User..hbm.xml

6.创建UserDao 类

public class UserDao implements IUserDao {

private static Session session;

static

{

// 1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.创建sessionFactory

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开session

session=sessionFactory.openSession();

}

1 .添加 (查看主键值是否返回) (User类)

Hibernate开启自动提交功能

public void addUser(User user) {// 此时为瞬时状态

//4.开启事物

Transaction tx= session.beginTransaction();

try {

// 5.持久化到数据库

// session.save(user);

session.persist(user);//持久化状态

//6. 提交事物

tx.commit();

} catch (HibernateException e) {

e.printStackTrace();

tx.rollback();

}finally

{

//7. 关闭session

session.close();

// 脱管状态

}

测试:

UserDao userDao=new UserDao();

User user =new User();

user.setPassword("zhangsan");

user.setUserName("张三");

userDao.addUser(user);

2.删除

public void deleteUser(int uid) {

Transaction tr=session.beginTransaction();

try {

User user=new User();

user.setUid(uid);

session.delete(user);

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

userDao.deleteUser(1);

3.修改

public void updateUser(User user) {

Transaction tr=session.beginTransaction();

try {

session.update(user);

//或者

//session.merge(user);

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

User user=new User();

user.setUid(2);

user.setPassword("lisi");

user.setUserName("李四");

userDao.updateUser(user);

4.查询（查询单个对象）

public User findUserByUid(int uid) {

User user=(User) session.get(User.class, uid);

session.close();

return user;

}

测试:

User user=userDao.findUserByUid(2);

System.out.println(user.getUserName()+","+user.getPassword());

5. load方法(懒加载)代理

public User findUserByUid1(int uid)

{

//注意：我们的实体类不能加上 final 关键字是因为懒加载会通过通过这个实体类派生一个子类出来实现懒加载(提供一个无参构造函数)

//所以上面的user这个对象永远不可能为null 如果没有查到懒加载也会生成一个子类对象

User user=(User)session.load(User.class, uid);

System.out.println(user.getClass().getName());

//System.out.println(user.getPassword());

//Hibernate.initialize(user);

session.close();

return user;

}

测试:

User user=userDao.findUserByUid1(2);

System.out.println(user.getUserName()+","+user.getPassword());

6. 更新或者保存

public void saveOrUpdateUser(User user)

{

Transaction tr=session.beginTransaction();

try {

session.saveOrUpdate(user);

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

User user=new User();

user.setPassword("王五");

user.setUserName("wangwu1");

user.setUid(6);

userDao.saveOrUpdateUser(user);

7.对象的状态(三个状态：瞬时状态，持久化状态，脱管状态)

8.如何动态生成表领域模型 (oop思想 --->创建数据库表)(Teacher类)

Teacher类:1.创建实体类 2. 创建 teacher.hbm.xml 3.hibernate.cfg.xml配置

在hibernate.cfg.xml 文件中添加如下内容:

<property name="hbm2ddl.auto">update</property>

如何用Xdoclet+ant 生成映射文件:

如何开始使用Xdoclet？

Xdoclet不是单独可以运行的工具（不像Ant工具），它可以与其它工具一起配合运行，如Ant。我们下面的例子就是基于Ant和xdoclet的。

1、首先需要保证ant是可用的

2、下载并解压xdoclet的包（我们现在使用的是xdoclet2，具体版本是xdoclet-plugins-1.0.3）。

3、在ant构建工具中定义xdoclet任务，并使用：

如何开始使用Ant？

1、确保你的机器已经安装了JDK，确保你的path环境变量中包含有java虚拟机的运行程序，确保你的环境变量中有JAVA_HOME变量

2、下载ant并解压

3、设置ANT_HOME环境变量，指向ant解压根目录

4、在path环境变量中，添加ANT_HOME\bin目录

5、打开控制台，运行：ant

6、如果能够运行ant（忽略这些异常：Buildfile: build.xml does not exist!），而不是出现诸如命令无法解释的错误，那么你的ant就安装成功了

1.创建com.hibernate.ant.bean包:

Test类:

/**

* @hibernate.class

* table="t_test"

* @author Administrator

*

*/

public class Test {

/**

* @hibernate.id

* generator-class="native"

*/

private int id;

/**

* @hibernate.property

*/

private String name;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

2.Src下放入build.xml文件:

<?xml version="1.0" encoding="GBK"?>

</fileset>

</fileset>

</path>

<taskdef

name="xdoclet"

classname="org.xdoclet.ant.XDocletTask"

classpathref="xdoclet.task.classpath"

/>

</fileset>

<component

classname="org.xdoclet.plugin.hibernate.HibernateMappingPlugin"

version="3.0"

destdir="${src.dir}"

/>

</xdoclet>

</target>

</project>

3.MyEclipse-Window-show View –other –Ant-Add Buildfiles –run as –Ant build

9.传统模型 (表生成实体类)(Student类)

用MyEclipse向导（MyEclipse DB Brower）

*************第二章***************

1． 一对多, 多对一(Emp表,Dept表)

Dept实体类:

/**

* 一对多

* @author Administrator

*

*/

public class Dept {

private int deptId;

private String deptName;//部门名称

private Set<Emp> emps;

public Dept(int deptId, String deptName, Set<Emp> emps) {

this.deptId = deptId;

this.deptName = deptName;

this.emps = emps;

}

public Dept() {

}

public int getDeptId() {

return deptId;

}

public void setDeptId(int deptId) {

this.deptId = deptId;

}

public String getDeptName() {

return deptName;

}

public void setDeptName(String deptName) {

this.deptName = deptName;

}

public Set<Emp> getEmps() {

return emps;

}

public void setEmps(Set<Emp> emps) {

this.emps = emps;

}

Dept.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<one-to-many class="com.hibernate.emp.bean.Emp" />

</set>

</class>

</hibernate-mapping>

Emp实体类:

/**

* 多对一

* @author Administrator

*

*/

public class Emp {

private int empId;

private String empName;

private Dept dept;

public Emp(int empId, String empName, Dept dept) {

this.empId = empId;

this.empName = empName;

this.dept = dept;

}

public Emp() {

}

public String getEmpName() {

return empName;

}

public void setEmpName(String empName) {

this.empName = empName;

}

public int getEmpId() {

return empId;

}

public void setEmpId(int empId) {

this.empId = empId;

}

public Dept getDept() {

return dept;

}

public void setDept(Dept dept) {

this.dept = dept;

}

Emp.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<many-to-one name="dept" column="dept_id" not-null="true"></many-to-one>

</class>

</hibernate-mapping>

实例：

1.一对多添加Dept部门

DeptDao类:

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public void addDept(Dept dept)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.persist(dept);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

DeptDao dd=new DeptDao();

Dept dept=new Dept();

dept.setDeptName("研发一部");

dd.addDept(dept);

2.多对一添加Emp表

EmpDao类:

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public void addEmp(Emp emp)

{

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.persist(emp);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

Emp emp=new Emp();

emp.setEmpName("李四");

Dept dept=new Dept();

dept.setDeptId(1);

dept.setDeptName("研发一部");

emp.setDept(dept);

ed.addEmp(emp);

3. 删除一个Dept部门 （同时删除部门下的人员）

public void deleteDept(int deptId)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.delete(session.get(Dept.class, deptId));

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

Dept.hbm.xml文件修改:

<one-to-many class="com.hibernate.emp.bean.Emp" />

</set>

解释:

inverse="true"

inverse是“反转”的意思，表示关联关系的控制权。为true，表示由对方负责关联关系的添加和删除；为false，表示由自己负责维护关联关系。(是否放弃维护关联关系 true 放弃关系)

cascade级联

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC7B.tmp.png all : 对所有操作都进行级联

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC7C.tmp.png none : 对所有操作都不进行级联

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC7D.tmp.png save-update : 执行添加更新操作时级联

file:///C:\Users\ADMINI~1\AppData\Local\Temp\ksohtml\wpsC7E.tmp.png delete : 执行删除操作时级联

lazy 表示懒加载为false 关闭懒加载为true 开启懒加载（默认）

4. 一对多添加Dept部门 同时添加人员

测试：

Dept dept=new Dept();

dept.setDeptName("研发一部");

Emp emp1=new Emp();

emp1.setDept(dept);

emp1.setEmpName("孙十");

Emp emp2=new Emp();

emp2.setDept(dept);

emp2.setEmpName("钱九");

Set<Emp> emps=new HashSet<Emp>();

emps.add(emp1);

emps.add(emp2);

dept.setEmps(emps);

dd.addDept(dept);

注意： cascade=”save-update”加上

5. 修改人员对应的部门

钱九孙十原来部门是研发一部

现在将钱九孙十调到研发三部

public void updateDept(Dept dept)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.update(dept);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

Dept dept=new Dept();

dept.setDeptId(3);

dept.setDeptName("研发三部");

Emp emp=new Emp();

emp.setEmpId(7);

emp.setEmpName("钱九");

emp.setDept(dept);

Emp emp1=new Emp();

emp1.setEmpId(8);

emp1.setEmpName("孙十");

emp1.setDept(dept);

Set<Emp> emps=new HashSet<Emp>();

emps.add(emp);

emps.add(emp1);

dept.setEmps(emps);

dd.updateDept(dept);

注意： cascade=”save-update”加上

6. 查询一个部门并查询出当前部门所有人员

public Dept findDeptByDeptId(int deptId)

{

Dept dept=(Dept)session.get(Dept.class, deptId);

session.close();

return dept;

}

测试:

Dept dept= dd.findDeptByDeptId(3);

System.out.println("部门名称:"+dept.getDeptName());

System.out.println("部门人员:");

for(Emp emp : dept.getEmps())

{

System.out.print(emp.getEmpName()+" ");

}

以上针对 Demp表进行增删改查操作

7. 多对一(Emp表) 删除(删除一个员工)

添加Emp 案例2已实现

EmpDao类:

public void deleteEmp(Emp emp)

{

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.delete(session.get(Emp.class, emp.getEmpId()));

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

Emp emp=new Emp();

emp.setEmpId(2);

ed.deleteEmp(emp);

8. 修改一个员工和部门

public void updateEmp(Emp emp)

{

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.merge(emp);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

Emp emp=new Emp();

emp.setEmpId(6);

emp.setEmpName("张三");

Dept dept=new Dept();

dept.setDeptId(3);

dept.setDeptName("研发三部");

emp.setDept(dept);

ed.updateEmp(emp);

9. 查询一个员工信息并显示对应部门

public Emp findEmpByEmpId(int empId)

{

Emp emp=(Emp) session.get(Emp.class, empId);

Hibernate.initialize(emp.getDept());

session.close();

return emp;

}

Emp emp=ed.findEmpByEmpId(6);

System.out.println("员工:"+emp.getEmpName());

System.out.println("所在部门:"+emp.getDept().getDeptName());

以上是Emp表增删改查操作

2． 多对多(Student表,Teacher表)

1.创建Teacher,Student实体类和 teacher.hbm.xml,student.hbm.xml

com.hibernate.student.bean包:

Student类:

/**

* 一对多

* @author Administrator

*

*/

public class Student {

private int studetnId;

private String studentName;

private Set<Teacher> teachers;

public int getStudetnId() {

return studetnId;

}

public void setStudetnId(int studetnId) {

this.studetnId = studetnId;

}

public String getStudentName() {

return studentName;

}

public void setStudentName(String studentName) {

this.studentName = studentName;

}

public Set<Teacher> getTeachers() {

return teachers;

}

public void setTeachers(Set<Teacher> teachers) {

this.teachers = teachers;

}

Student.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<!—级联添加学生允许添加/修改/删除老师 -->

<!—t_student_teacher 表中那个外键与student 表studentId主键对应 -->

<many-to-many class="com.hibernate.teacher.bean.Teacher" column="teacher_id"></many-to-many>

</set>

</class>

</hibernate-mapping>

Teacher类:

/**

* 一对多

* @author Administrator

*

*/

public class Teacher {

private int teacherId;

private String teacherName;

private Set<Student> students;

public int getTeacherId() {

return teacherId;

}

public void setTeacherId(int teacherId) {

this.teacherId = teacherId;

}

public String getTeacherName() {

return teacherName;

}

public void setTeacherName(String teacherName) {

this.teacherName = teacherName;

}

public Set<Student> getStudents() {

return students;

}

public void setStudents(Set<Student> students) {

this.students = students;

}

Teacher.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<!—老师放弃维护关系由学生维护这时学生才有权限t_student_teacher 表添加修改权限 -->

<many-to-many class="com.hibernate.student.bean.Student" column="student_id"></many-to-many>

</set>

</class>

</hibernate-mapping>

实例:

1. 添加一个学生

StudentDao类:

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public void addStudent(Student student)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.persist(student);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

StudentDao sd=new StudentDao();

Student student =new Student();

student.setStudentName("张三");

sd.addStudent(student);

2.添加老师

TeacherDao类:

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public void addTeacher(Teacher teacher)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.persist(teacher);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试：

TeacherDao td=new TeacherDao();

Teacher teacher=new Teacher();

teacher.setTeacherName("刘老师");

td.addTeacher(teacher);

3. 添加一个学生和老师但是两者没有关系如何建立关系呢?

设置学生为维护端(由于操作学生)

teacher.hbm.xml set标签中添加 inverse="true"

（老师放弃维护端由学生来维护）

public void update(Student student)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.update(student);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试：

Student student=new Student();

student.setStudetnId(1);

student.setStudentName("张三");

Teacher teacher=new Teacher();

teacher.setTeacherId(1);

teacher.setTeacherName("刘老师");

HashSet<Teacher> teachers=new HashSet<Teacher>();

teachers.add(teacher);

student.setTeachers(teachers);

HashSet<Student> students=new HashSet<Student>();

students.add(student);

teacher.setStudents(students);

sd.update(student);

4.添加学生，老师建立两者关系 (级联添加 student 添加 cascade="save-update,delete")

添加学生同时允许同时添加老师

测试:

Student student =new Student();

student.setStudentName("李四");

Teacher teacher=new Teacher();

teacher.setTeacherName("赵老师");

HashSet<Student> students=new HashSet<Student>();

students.add(student);

teacher.setStudents(students);

HashSet<Teacher> teachers=new HashSet<Teacher>();

teachers.add(teacher);

student.setTeachers(teachers);

sd.addStudent(student);

5. 添加一个学生分配给xx老师

测试:

Student student =new Student();

student.setStudentName("孙十1");

Teacher teacher =new Teacher();

teacher.setTeacherId(2);

teacher.setTeacherName("赵老师");

//老师端添加学生集合

HashSet<Student> students=new HashSet<Student>();

students.add(student);

teacher.setStudents(students);

//学生端添加老师集合

HashSet<Teacher> teachers=new HashSet<Teacher>();

teachers.add(teacher);

student.setTeachers(teachers);

sd.addStudent(student);

6. 删除 (删除同学不应该同时删除老师吧所以学生端级联不应该加上 delete)

由于由 student维护关系所以学生可以操作t_student_teacher表

public void deleteStudent(Student student)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.delete(student);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

Student student=new Student();

student.setStudentName("张三");

student.setStudetnId(1);

sd.deleteStudent(student);

7. 修改将xx同学更换成xx老师 (老师换了)

测试:

Student student=new Student();

student.setStudentName("李四");

student.setStudetnId(2);

Teacher teacher=new Teacher();

teacher.setTeacherId(1);

teacher.setTeacherName("刘老师");

HashSet<Teacher> teachers=new HashSet<Teacher>();

teachers.add(teacher);

HashSet<Student> students=new HashSet<Student>();

students.add(student);

teacher.setStudents(students);

student.setTeachers(teachers);

sd.update(student);

8. 查询 xx同学对应的老师

public Student findStudentByStudentId(int studentId)

{

Student student=(Student)session.get(Student.class, studentId);

Hibernate.initialize(student.getTeachers());

session.close();

return student;

}

测试：

Student student= sd.findStudentByStudentId(2);

System.out.println("学生:"+student.getStudentName());

System.out.println("对应老师:");

for(Teacher teacher : student.getTeachers())

{

System.out.println(teacher.getTeacherName());

}

3． 一对一(Person表,IdCard表)

Person类:

public class Person {

private int id;

private String personName;

private IdCard idCard;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getPersonName() {

return personName;

}

public void setPersonName(String personName) {

this.personName = personName;

}

public IdCard getIdCard() {

return idCard;

}

public void setIdCard(IdCard idCard) {

this.idCard = idCard;

}

Person.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<one-to-one name="idCard" cascade="save-update,delete"></one-to-one>

</class>

</hibernate-mapping>

IdCard类:

public class IdCard {

private int id;

private String cardNumber;

private Person person;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public Person getPerson() {

return person;

}

public void setPerson(Person person) {

this.person = person;

}

public String getCardNumber() {

return cardNumber;

}

public void setCardNumber(String cardNumber) {

this.cardNumber = cardNumber;

}

Idcard.html.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

<param name="property">person</param>

</generator>

</id>

<one-to-one name="person"></one-to-one>

</class>

</hibernate-mapping>

实例:

PersonDao类:

一对一主键对主键

1. 添加一个人并且分配一个身份证:

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public void addPerson(Person person)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.persist(person);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

PersonDao pd=new PersonDao();

Person person =new Person();

person.setPersonName("张三");

IdCard idCard=new IdCard();

idCard.setCardNumber("123456789012345678");

//双向关联

idCard.setPerson(person);

person.setIdCard(idCard);

pd.addPerson(person);

2. 删除一个人 (当前是主键看对idcard id外键是否有影响)

constrained="true" 表示存在一个主外键约束

public void deletePerson(Person person)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.delete(person);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

Person person =new Person();

person.setPersonName("张三");

person.setId(1);

pd.deletePerson(person);

结果：对idcard表没有影响，因为person 表与 idcard表没有建立主外键关系

3. 删除一个人身份证也删除

测试:

Person person =new Person();

person.setPersonName("张三");

person.setId(1);

IdCard idCard=new IdCard();

idCard.setId(1);

idCard.setCardNumber("11111111111111111111");

person.setIdCard(idCard);

pd.deletePerson(person);

4. 修改一个人身份证号码

public void updateIdCard(IdCard idCard)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.update(idCard);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

IdCard idCard=new IdCard();

idCard.setId(2);

idCard.setCardNumber("1111111111");

pd.updateIdCard(idCard);

5. 查询一个人并且显示身份证号:

public Person findPersonById(int id)

{

Person person=(Person)session.get(Person.class, id);

session.close();

return person;

}

测试:

Person person= pd.findPersonById(2);

System.out.println("人:"+person.getPersonName());

System.out.println(

"身份证:"+person.getIdCard().getCardNumber());

一对一主键对外键

com.hibernate.person.other.bean包:

PersonOther类:

public class PersonOther {

private int personId;

private String personName;

private IdCardOther idCardOther;

public int getPersonId() {

return personId;

}

public void setPersonId(int personId) {

this.personId = personId;

}

public String getPersonName() {

return personName;

}

public void setPersonName(String personName) {

this.personName = personName;

}

public IdCardOther getIdCardOther() {

return idCardOther;

}

public void setIdCardOther(IdCardOther idCardOther) {

this.idCardOther = idCardOther;

}

Personother.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<one-to-one name="idCardOther" property-ref="personOther" cascade="save-update,delete"></one-to-one>

</class>

</hibernate-mapping>

com.hibernate.idcard.other.bean包:

IdCardOther类:

public class IdCardOther {

private int cardId;

private String cardNumber;

private PersonOther personOther;

public int getCardId() {

return cardId;

}

public void setCardId(int cardId) {

this.cardId = cardId;

}

public String getCardNumber() {

return cardNumber;

}

public void setCardNumber(String cardNumber) {

this.cardNumber = cardNumber;

}

public PersonOther getPersonOther() {

return personOther;

}

public void setPersonOther(PersonOther personOther) {

this.personOther = personOther;

}

Idcardother.hbm.xml文件：

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

<many-to-one name="personOther" column="person_id" unique="true" not-null="true"></many-to-one>

</class>

</hibernate-mapping>

实例:

PersonOtherDao类:

1.添加一个人并且分配一个身份证

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public void addPerson(PersonOther personOther)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.persist(personOther);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

PersonOtherDao pod=new PersonOtherDao();

PersonOther personOther=new PersonOther();

personOther.setPersonName("张三");

IdCardOther idCardOther=new IdCardOther();

idCardOther.setCardNumber("112233445566778899");

//配置双向

idCardOther.setPersonOther(personOther);

personOther.setIdCardOther(idCardOther);

pod.addPerson(personOther);

2. 删除一个人身份证也删除

public void deletePerson(PersonOther person)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.delete(person);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

PersonOther personOther=new PersonOther();

personOther.setPersonId(1);

personOther.setPersonName("张三");

IdCardOther idCardOther=new IdCardOther();

idCardOther.setCardId(1);

idCardOther.setCardNumber("112233445566778899");

idCardOther.setPersonOther(personOther);

personOther.setIdCardOther(idCardOther);

pod.deletePerson(personOther);

3. 修改一个人身份证号码

public void updateIdCard(IdCardOther idCard)

{

//4. 开启事物

Transaction tr=session.beginTransaction();

try {

//5. 持久化

session.update(idCard);

//6.提交

tr.commit();

} catch (HibernateException e) {

// TODO Auto-generated catch block

e.printStackTrace();

tr.rollback();

}finally

{

session.close();

}

测试:

IdCardOther idCard=new IdCardOther();

idCard.setCardId(2);

idCard.setCardNumber("1111111111");

PersonOther personOther=new PersonOther();

personOther.setPersonId(2);

personOther.setPersonName("张三");

idCard.setPersonOther(personOther);

pod.updateIdCard(idCard);

4. 查询一个人并且显示身份证号

public PersonOther findPersonById(int id)

{

PersonOther person=(PersonOther)session.get(PersonOther.class, id);

session.close();

return person;

}

测试:

PersonOther person= pod.findPersonById(2);

System.out.println("人:"+person.getPersonName());

System.out.println("身份证:"+person.getIdCardOther().getCardNumber());

一对一主键对主键，主键对外键关联结束

**************第三章************

1. HQL语句:

Hibernate Query Lanuage

Hibernate查询语言

HQL是面向对象的查询语言

实例:

Fwxx类:

public class Fwxx {

private int fwid;

private int uid;

private int jdid;

private int lxid;

private int shi;

private int ting;

private String fwxx;

private float zj;

private String title;

private String date;

private String telephone;

private String lxr;

public int getFwid() {

return fwid;

}

public void setFwid(int fwid) {

this.fwid = fwid;

}

public int getUid() {

return uid;

}

public void setUid(int uid) {

this.uid = uid;

}

public int getJdid() {

return jdid;

}

public void setJdid(int jdid) {

this.jdid = jdid;

}

public int getLxid() {

return lxid;

}

public void setLxid(int lxid) {

this.lxid = lxid;

}

public int getShi() {

return shi;

}

public void setShi(int shi) {

this.shi = shi;

}

public int getTing() {

return ting;

}

public void setTing(int ting) {

this.ting = ting;

}

public String getFwxx() {

return fwxx;

}

public void setFwxx(String fwxx) {

this.fwxx = fwxx;

}

public float getZj() {

return zj;

}

public void setZj(float zj) {

this.zj = zj;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public String getDate() {

return date;

}

public void setDate(String date) {

this.date = date;

}

public String getTelephone() {

return telephone;

}

public void setTelephone(String telephone) {

this.telephone = telephone;

}

public String getLxr() {

return lxr;

}

public void setLxr(String lxr) {

this.lxr = lxr;

}

Fwxx.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

</class>

<![CDATA[select fwxx from Fwxx as fwxx where fwxx.fwid= :fwid]]>

</query>

<sql-query name="findFwxxByFwidForSql">

<![CDATA[select * from tbl_fwxx where fwid=:fwid]]>

</sql-query>

</hibernate-mapping>

1. 创建表

//创建表

public void createTable()

{

Configuration cfg=new Configuration().configure();

new SchemaExport(cfg).create(true, true);

}

测试:

FwxxDao fd=new FwxxDao();

fd.createTable();

2. 查询所有房屋信息并且按照发布时间排序

public List<Fwxx> findAllFwxx()

{

String hql="select fwxx from Fwxx as fwxx order by fwxx.date desc";

Query query= session.createQuery(hql);

List<Fwxx> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList=fd.findAllFwxx();

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getLxr()+

","+fwxx.getDate()+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

3. 只查询 fwxx表 title信息

public List<String> findAllFwxx1()

{

String hql="select fwxx.title from Fwxx as fwxx order by fwxx.date desc";

Query query= session.createQuery(hql);

List<String> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List<String> titleList= fd.findAllFwxx1();

for(String title : titleList)

{

System.out.println(title);

}

4. 只查询 fwxx表 date 和title这两列（为性能考虑）

public List findAllFwxx2()

{

String hql="select fwxx.date,fwxx.title from Fwxx as fwxx order by fwxx.date desc";

Query query=session.createQuery(hql);

List<Fwxx> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List fwxxList=fd.findAllFwxx2();

for(int i=0;i<fwxxList.size();i++)

{

Object[] fwxxs=(Object[])fwxxList.get(i);

System.out.println(fwxxs[0]+","+fwxxs[1]);

}

5. 根据title模糊查询房屋信息

public List<Fwxx> findFwxxByTitle(String title)

{

String hql="select fwxx from Fwxx as fwxx where fwxx.title like '%"+title+"%'";

Query query=session.createQuery(hql);

List<Fwxx> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxByTitle("二居");

for(Fwxx fwxx : fwxxList){

System.out.println(fwxx.getLxr()+","+fwxx.getDate()

+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

6. 使用 ? 占位符title模糊查询房屋信息

Query提供setLong,setDouble,setDate等方法用于设置不同类型的参数值

注意：

1. 必须保证：query设置参数的数目 == hql语句中占位符的数目

2. 占位符下标从 0 开始。

public List<Fwxx> findFwxxByTitle1(String title)

{

String hql="select fwxx from Fwxx as fwxx where fwxx.title like ?";

Query query=session.createQuery(hql);

query.setString(0, "%"+title+"%");

List<Fwxx> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxByTitle1("二居");

for(Fwxx fwxx : fwxxList){

System.out.println(fwxx.getLxr()+","+fwxx.getDate()

+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

7. 查询租金在zj1到zj2范围内的租房信息

支持： >、< 、 = 、 >= 、 <= 、<>(不等于) 和is null;and、or、not和括号；in和between

public List<Fwxx> findFwxxByZj(int zj1,int zj2)

{

String hql="select fwxx from Fwxx as fwxx where fwxx.zj>? and fwxx.zj<?";

Query query=session.createQuery(hql);

query.setInteger(0, zj1);

query.setInteger(1, zj2);

List<Fwxx> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxByZj(200, 1000);

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getZj()+","+fwxx.getDate()

+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

8. 当参数数目增多时，代码可读性下降；将下标顺序硬编码，参数顺序有调整则代码也要调整使用“:参数名”的格式定义命名参数

public List<Fwxx> findFwxxByZj1(int zj1,int zj2)

{

String hql="select fwxx from Fwxx as fwxx where fwxx.zj> :zj1 and fwxx.zj< :zj2";

Query query=session.createQuery(hql);

// query.setInteger(0, zj1);

// query.setInteger(1, zj2);

query.setInteger("zj2", zj2);

query.setInteger("zj1", zj1);

List<Fwxx> fwxxList= query.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxByZj1(200, 1000);

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getZj()+","

+fwxx.getDate()+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

9. 如何两张表关联查询 fwxx表 jd表

例如:联系人为“王先生”的房屋信息都分布在哪些街道

com.hibernate.jd.bean包：

Jd类:

public class Jd {

private int jdId;

private String jd;

private int qxid;

public int getJdId() {

return jdId;

}

public void setJdId(int jdId) {

this.jdId = jdId;

}

public String getJd() {

return jd;

}

public void setJd(String jd) {

this.jd = jd;

}

public int getQxid() {

return qxid;

}

public void setQxid(int qxid) {

this.qxid = qxid;

}

Jd.hbm.xml文件:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping >

</id>

</class>

</hibernate-mapping>

public List findFwxxBylxr(String lxr)

{

String hql="select fwxx.title,jd.jd from Fwxx as fwxx,Jd as jd where fwxx.jdid=jd.jdId and fwxx.lxr=:lxr";

Query query=session.createQuery(hql);

query.setString("lxr", lxr);

List list=query.list();

session.close();

return list;

}

测试:

List list= fd.findFwxxBylxr("王先生");

for(int i=0;i<list.size();i++)

{

Object[] fwxxs=(Object[])list.get(i);

System.out.println(fwxxs[0]+","+fwxxs[1]);

}

10. 分页查询fwxx

public List<Fwxx> findFwxxForPage(int start,int pageSize)

{

String hql="select fwxx from Fwxx as fwxx ";

Query query= session.createQuery(hql);

query.setFirstResult(start);//开始条数

query.setMaxResults(pageSize);//每页最大显示条数

List list=query.list();

session.close();

return list;

}

测试:

List<Fwxx> fwxxList = fd.findFwxxForPage(2, 2);

for(Fwxx fwxx : fwxxList){

System.out.println(fwxx.getLxr()+","

+fwxx.getDate()+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

统计函数count() ,min()、max()、avg()

11. 在实现分页功能时，我们需要知道总记录数以便计算总页数

public long findFwxxTotalCount()

{

String hql="select count(fwxx) from Fwxx as fwxx";

Query query=session.createQuery(hql);

// 返回单个对象可以用uniqueResult方法

long totalCount=(Long)query.uniqueResult();

session.close();

return totalCount;

}

测试:

System.out.println("总条数:"+fd.findFwxxTotalCount());

12. 查询所有住房的平均租金

public Double findFwxxZJAvg()

{

String hql="select avg(fwxx.zj) from Fwxx as fwxx";

Query query=session.createQuery(hql);

// 返回单个对象可以用uniqueResult方法

Double zj=(Double)query.uniqueResult();

session.close();

return zj;

}

测试:

System.out.println("平均租金:"+fd.findFwxxZJAvg());

13. hql 语句与代码分离

public Fwxx findFwxxByFwidForHql(int fwid)

{

Query query= session.getNamedQuery("findFwxxByFwid");

query.setInteger("fwid", fwid);

Fwxx fwxx=(Fwxx)query.uniqueResult();

session.close();

return fwxx;

}

Fwxx.hbm.xml文件加入：

<![CDATA[select fwxx from Fwxx as fwxx where fwxx.fwid= :fwid]]>

</query>

测试:

Fwxx fwxx= fd.findFwxxByFwidForHql(1);

System.out.println(fwxx.getTitle()+" "+fwxx.getFwxx());

14. 写sql语句查询

public Fwxx findFwxxByFwidForSql(int fwid)

{

String sql="select * from tbl_fwxx where fwid=:fwid";

SQLQuery sqlQuery= session.createSQLQuery(sql);

sqlQuery.setInteger("fwid",fwid);

Fwxx fwxx=(Fwxx)sqlQuery.addEntity(Fwxx.class).uniqueResult();

session.close();

return fwxx;

}

测试:

Fwxx fwxx=fd.findFwxxByFwidForSql(1);

System.out.println(fwxx.getTitle()+" "+fwxx.getFwxx());

15. 写sql语句查询与代码分离

public Fwxx findFwxxByFwidForSql1(int fwid)

{

Query Query= session.getNamedQuery("findFwxxByFwidForSql");

Query.setInteger("fwid",fwid);

Fwxx fwxx=(Fwxx)Query.uniqueResult();

session.close();

return fwxx;

}

Fwxx.hbm.xml文件：

<sql-query name="findFwxxByFwidForSql">

<![CDATA[select * from tbl_fwxx where fwid=:fwid]]>

</sql-query>

测试:

Fwxx fwxx=fd.findFwxxByFwidForSql1(1); System.out.println(fwxx.getTitle()+" "+fwxx.getFwxx());

使用 Criteria对象查询

16. 基于Criteria对象查询所有房屋信息

public List<Fwxx> findAllFwxxForCriteria()

{

Criteria criteria= session.createCriteria(Fwxx.class);

criteria.addOrder(Order.desc("date"));

List<Fwxx> fwxxList= criteria.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findAllFwxxForCriteria();

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getLxr()+","

+fwxx.getDate()+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

17. 基于Criteria对象模糊查询title

public List<Fwxx> findFwxxTitleForCriteria(String title)

{

Criteria criteria= session.createCriteria(Fwxx.class);

criteria.add(Restrictions.ilike("title", title,MatchMode.ANYWHERE));

criteria.addOrder(Order.desc("date"));

List<Fwxx> fwxxList=criteria.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxTitleForCriteria("二居");

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getLxr()+","+fwxx.getDate()+","

+fwxx.getFwxx()+","+fwxx.getTitle());

}

18. 基于Criteria对象查询租金范围

public List<Fwxx> findFwxxZjForCriteria(float zj1,float zj2)

{

Criteria criteria= session.createCriteria(Fwxx.class);

// criteria.add(Restrictions.between("zj", zj1, zj2));

criteria.add(Restrictions.ge("zj", zj1)); //ge >= gt >

criteria.add(Restrictions.le("zj", zj2));// le <= lt <

criteria.addOrder(Order.desc("date"));

List<Fwxx> fwxxList=criteria.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxZjForCriteria(400f, 1000f);

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getZj()+","+fwxx.getLxr()+

","+fwxx.getDate()+","+fwxx.getFwxx()+","+fwxx.getTitle());

}

19. 基于Criteria对象查询单个 Fwxx对象

public Fwxx findFwxxByFwidForCriteria(int fwid)

{

Criteria criteria= session.createCriteria(Fwxx.class);

criteria.add(Restrictions.eq("fwid", fwid));

Fwxx fwxx= (Fwxx) criteria.uniqueResult();

session.close();

return fwxx;

}

测试:

Fwxx fwxx= fd.findFwxxByFwidForCriteria(1);

System.out.println(fwxx.getZj()+","+fwxx.getLxr()+","

+fwxx.getDate()+","+fwxx.getFwxx()+","+fwxx.getTitle());

20. 基于Criteria对象分页

public List<Fwxx> findFwxxPageForCriteria(int start,int pageSize)

{

Criteria criteria= session.createCriteria(Fwxx.class);

criteria.addOrder(Order.desc("date"));

criteria.setFirstResult(start);

criteria.setMaxResults(pageSize);

List<Fwxx> fwxxList=criteria.list();

session.close();

return fwxxList;

}

测试:

List<Fwxx> fwxxList= fd.findFwxxPageForCriteria(0, 2);

for(Fwxx fwxx : fwxxList)

{

System.out.println(fwxx.getZj()+","+fwxx.getLxr()+

","+fwxx.getDate()+","+fwxx.getFwxx()

+","+fwxx.getTitle());

}

缓存

缓存的作用主要用来提高性能，可以简单的理解成一个Map；使用缓存涉及到三个操作：把数据放入缓存、从缓存中获取数据、删除缓存中的无效数据。

一级缓存，Session级共享。

save,update,saveOrUpdate,load,get,list,iterate这些方法都会将对象放在一级缓存中，一级缓存不能控制缓存的数量，所以要注意大批量操作数据时可能造成内存溢出；可以用evict,clear方法清除缓存中的内容

实例:

com.hibernate.cache.dao包:

UserCacheDao类:

private static Session session;

static{

//1.读取hibernate.cfg.xml文件

Configuration cfg=new Configuration().configure();

//2.绑定sessionFactoru

SessionFactory sessionFactory= cfg.buildSessionFactory();

//3.打开 session

session= sessionFactory.openSession();

}

public User findUserByUid(int uid)

{

System.out.println("没有开始缓存");

User user=(User)session.get(User.class, uid);

System.out.println("将User对象缓存到session中");

System.out.println("用户名:"+user.getUserName());

System.out.println("关闭数据库.....");

try {

Thread.sleep(1000*15);//休息15秒

} catch (Exception e) {

// TODO: handle exception

}

// session.clear();

System.out.println("数据库已经关闭....");

User userCache= (User) session.get(User.class, uid);// 从缓存中获取

System.out.println("缓存数据用户名:"+userCache.getUserName());

session.close();

return user;

}

测试:

//1. 一级session 缓存测试

UserCacheDao ucd=new UserCacheDao();

ucd.findUserByUid(1);

二级缓存，SessionFactory级共享。

l hibernate内置了对EhCache,OSCache,TreeCache,SwarmCache的支持

这里使用 EhCache为例:

1. 导包 : ehcache-1.2.3.jar

2. 开启二级缓存：

Hibernate.cfg.xml文件中添加:

3. 添加hibernate缓存入口类(类似jdbc驱动类)

org.hibernate.cache.EhCacheProvider

</property>

4. src目录下添加ehcache.xml

<?xml version="1.0" encoding="UTF-8"?>

<!--

defaultCache 节点为缺省的缓存策越

maxElementsInMemory 内存中最大允许存在的对象数量

eternal 设置缓存中的对象是否永久不过期

overflowToDik 把溢出的对象存放到硬盘上

timeToIdleSeconds 指定缓存对象空闲多长时间就过期，过期的对象会被清除掉

timeToLiveSeconds 指定缓存对象总的存活时间

diskPersistent 当jvm（java虚拟机）结束时是否持久化对象

diskExpiryThreadIntervalSeconds 指定专门用于清除过期对象的监听线程的轮询时间

-->

<!-- 定义缓存的默认行为

maxElementsInMemory:缓存中最大存放的对象

eternal:缓存对象是否永远不过期

overflowToDisk:缓存中对象数量超过设置最大的存放的数量时是否把超过的对象放到磁盘上

diskExpiryThreadIntervalSeconds:设置一个时间专门有一个线程来清除过期的缓存对象

-->

<defaultCache

maxElementsInMemory="1000"

eternal="false"

overflowToDisk="true"

timeToIdleSeconds="120"

timeToLiveSeconds="180"

diskPersistent="false"

diskExpiryThreadIntervalSeconds="60"

/>

<cache name="com.hibernate.student.bean.Student" maxElementsInMemory="5" eternal="false"

overflowToDisk="true" timeToIdleSeconds="300" timeToLiveSeconds="600" diskPersistent="false"/>

<cache name="com.hibernate.user.bean.User" maxElementsInMemory="5" eternal="false"

overflowToDisk="true" timeToIdleSeconds="300" timeToLiveSeconds="600" diskPersistent="false"/>

</ehcache>

5. user.hbm.xml文件添加缓存

准备工作完成测试:

二级sessionFactory 缓存测试(get一级缓存没有查询到，二级缓存查询)

public User findUserByUid1ForGet(int uid)

{

System.out.println("没有开始缓存...");

User user= (User) session.get(User.class, uid);

System.out.println("user对象缓存到一级缓存中");

session.clear();

session.close();// 关闭 session

System.out.println("一级缓存关闭，user对象清空，会将对象放入二级缓存中");

System.out.println("请关闭数据库....");

try {

Thread.sleep(1000*15);//休息15秒

} catch (Exception e) {

// TODO: handle exception

}

System.out.println("开始从二级缓存中查询数据...");

Session s= sessionFactory.openSession();

User u=(User) s.get(User.class, uid);

System.out.println(u.getUserName());

s.close();

return user;

}

测试:

ucd.findUserByUid1ForGet(1);

Hql语句缓存（查询缓存）

l (查询缓存)由于命中率较低，所以hibernate缺省是关闭；修改cache.use_query_cache为true打开对查询的缓存，并且调用query.setCacheable(true)或criteria.setCacheable(true)

1. hibernate.cfg.xml文件添加

开启查询缓存

2.代码中 query.setCacheable(true)或criteria.setCacheable(true)

public List<User> findUserByUid2ForHql(int uid)

{

Query query= session.createQuery("from User as user where user.uid="+uid);

query.setCacheable(true);//设置开启hql语句缓存默认关闭

query.uniqueResult();

session.clear();

session.close();

System.out.println("请关闭数据库....");

try {

Thread.sleep(1000*15);//休息15秒

} catch (Exception e) {

// TODO: handle exception

}

Session s= sessionFactory.openSession();

Query q= s.createQuery("from User as user where user.uid="+uid);

q.setCacheable(true);

User user=(User) q.uniqueResult();

System.out.println(user.getUserName());

return null;

}

测试:

ucd.findUserByUid2ForHql(1);