Hibernate 基于mysql开发

最新推荐文章于 2024-07-30 18:36:42 发布

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最新推荐文章于 2024-07-30 18:36:42 发布

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分类专栏： hibernate 文章标签： hibernate

本文链接：https://blog.youkuaiyun.com/kebexue/article/details/96698284

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-》下载hibernate版本：

hibernate-release-5.4.3.Final.zip

Esclipse开发

添加相应的hibernate库到工程中

具体库如下：该目录下我的全选了，有些是用不到的，懒的一个一个的选，

jpa这个库我跟网上的不一样，怀疑是版本的问题

新建表：

create table grade
(
   gid int primary key,
   gname varchar(20) not null,
   gdesc varchar(64)
);

create table student_info
(
   sid int primary key,
   sname varchar(20) not null,
   sex char(2),
   gid int
);

alter table student_info add constraint fk_student_id foreign key(gid)
references grade(gid);

创建Grade类对象

package com.alex.entity;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

public class Grade implements Serializable {
   private int gid;
   private String gname;
   private String gdesc;

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

   public int getGid() {
       return gid;
   }

   public void setGid(int gid) {
       this.gid = gid;
   }

   public String getGname() {
       return gname;
   }

   public void setGname(String gname) {
       this.gname = gname;
   }

   public String getGdesc() {
       return gdesc;
   }

   public void setGdesc(String gdesc) {
       this.gdesc = gdesc;
   }

   public Set<Student> getStudents() {
       return students;
   }

   public void setStudents(Set<Student> students) {
       this.students = students;
   }

   public Grade() {
       super();
   }
   public Grade(int gid, String gname, String gdesc, Set<Student> students) {
       super();
       this.gid = gid;
       this.gname = gname;
       this.gdesc = gdesc;
       this.students = students;
   }

   public Grade(String gname, String gdesc) {
       super();
       this.gname = gname;
       this.gdesc = gdesc;
   }

}

创建student_info类

package com.alex.entity;

import java.io.Serializable;

public class Student implements Serializable {
   private int sid;
   private String sname;
   private String sex;
   public int getSid() {
       return sid;
   }
   public void setSid(int sid) {
       this.sid = sid;
   }
   public String getSname() {
       return sname;
   }
   public void setSname(String sname) {
       this.sname = sname;
   }
   public String getSex() {
       return sex;
   }
   public void setSex(String sex) {
       this.sex = sex;
   }

   public Student() {
       super();
   }
   public Student(String sname, String sex) {
       super();
       this.sname = sname;
       this.sex = sex;
   }

}

创建配置文件

文件名称为Grade.hbm.xml

跟数据库要字段要一一对应

<?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">

<hibernate-mapping >

<one-to-many class = "com.alex.entity.Student"></one-to-many>

       </set>
   </class>
</hibernate-mapping>

配置文件：Student.hbm.xml

<hibernate-mapping >

创建映射文件

<!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>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password"> ******</property>
<property name="hibernate.connection.url">
           <![CDATA[
               jdbc:mysql://192.168.8.xxx/student?useUnicode=true&characterEncoding=utf8
           ]]>
       </property>
       <property name="show_sql">true</property> ##是否将sql语句输出到控制台上

<propety name="format_sql">true</property> ##输出到控制台的sql是否要格式化，排版
       <property name="hbm2ddl_auto">update</property> ##生成数据库脚本
       <property name="hibernate.current_session_context_class">jta</property>

<mapping resource = "/hibernate_one2many/src/com/alex/entity/Grade.hbm.xml"></mapping>
<mapping resource = "/hibernate_one2many/src/com/alex/entity/Student.hbm.xml"></mapping>
</session-factory>
</hibernate-configuration>

构建工厂类

package com.alex.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;

import com.alex.entity.Grade;
import com.alex.entity.Student;

//工具类
public class hibernateUtil {
   private static SessionFactory sessionFactory;
   private static Session session;
   static
   {
       Configuration conf = new Configuration().configure();
       //unknown entity异常
       conf.addClass(Grade.class);
       conf.addClass(Student.class);
       StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder()
               .applySettings(conf.getProperties());
       StandardServiceRegistry ssr = ssrb.build();
       sessionFactory = conf.buildSessionFactory(ssr);
   }

   //获取SessionFactory
   public static SessionFactory getSessionFactory(){
       return sessionFactory;
   }

   public static Session getSession(){
       session = sessionFactory.openSession();
       return session;
   }

   //关闭session
   public static void closesession(Session session){
       if(session != null){
           session.close();
       }
   }

}

测试用例

package com.alex.test;

import java.util.Set;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;

import com.alex.entity.Grade;
import com.alex.entity.Student;
import com.alex.hibernate.hibernateUtil;

public class testDemo {

   public static void main(String[] args) throws Exception {
       // TODO Auto-generated method stub
       add();
   }

   public static void add(){
       Grade grade = new Grade("Java","java development ");
       Student stu1 = new Student("Alex","M");
       Student stu2 = new Student("Amy","F");

       grade.getStudents().add(stu1);
       grade.getStudents().add(stu2);
       hibernateUtil hibernate = new hibernateUtil();
       Session session = hibernate.getSession();

       Transaction transaction = session.beginTransaction();
       session.save(grade);
       session.save(stu1);
       session.save(stu2);
       transaction.commit();
       hibernateUtil.closesession(session);

   }

   public static void findStudent(){
       Session session = hibernateUtil.getSession();
       Grade grade = session.get(Grade.class,1);
       System.out.println(grade.getGname()+","+grade.getGdesc());

       Set<Student> students = grade.getStudents();
       for(Student student:students){
           System.out.println(student.getSname()+"-->"+student.getSex());
       }
   }

}

结果：

报错：

unknown entity异常自己定义的类找不到

解决方案：版本的问题，据说是5.0以上版本需要这么添加

多对一关联

类中添加相应的类

配置修改Student.hbm.xml

<hibernate-mapping >

测试程序

package com.alex.test;

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.alex.entity.Grade;
import com.alex.entity.Student;
import com.alex.hibernate.hibernateUtil;

public class testDemo02 {

   public static void main(String[] args) {
       // TODO Auto-generated method stub
       save();
   }

   public static void save(){
       Grade grade = new Grade("bigdata","bigdata development");
       Student st1 = new Student("Kobe","M");
       Student st2 = new Student("James","M");

       st1.setGrade(grade);
       st2.setGrade(grade);
       hibernateUtil util = new hibernateUtil();
       Session session = hibernateUtil.getSession();
       Transaction transaction = session.beginTransaction();
       session.save(grade);
       session.save(st1);
       session.save(st2);
       transaction.commit();
       util.closesession(session);
   }
}