hibernate5小案例讲解

Posted 2020-10-06 花娣丫头小愤青

Student类

package com.wangning.bean;

public class Student {
private Integer id;
private String name;
private int age;
private double score;
@Override
public String toString() {
    return "Student [id=" + id + ", name=" + name + ", age=" + age + ", score="
            + score + "]";
}
public Student() {
    super();
}
public Student(String name, int age, double score) {
    super();
    this.name = name;
    this.age = age;
    this.score = score;
}
public Integer getId() {
    return id;
}
public void setId(Integer id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}
public double getScore() {
    return score;
}
public void setScore(double score) {
    this.score = score;
}
}

View Code

Student.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.wangning.bean">
    <!-- 映射文件的作用：
            1、完成类到表的映射 2、属性到字段的映射 -->
    <class name="Student" table="t_student">
        <id name="id" column="tid">
            <generator class="native"></generator>
        </id>
        <property name="name" column="tname"></property>
        <property name="age" column="tage"></property>
        <property name="score" column="tscore"></property>
    </class>
</hibernate-mapping>

 

hibernate.cfg.xml  

<?xml version="1.0" encoding="UTF-8"?>
<!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>
        <!-- DB链接4要素 -->
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql:///world</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">huadiyatou1314</property>
        <!-- 方言 -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
        <!-- 数据源 :数据连接池-->
        <property name="hibernate.connection.provider_class">org.hibernate.c3p0.internal.C3P0ConnectionProvider</property>
        <!-- 当前session上下文:保证统一线程获取到的session是同一个-->
        <property name="hibernate.current_session_context_class">thread</property>
        <!-- 自动建表 -->
        <property name="hibernate.hbm2ddl.auto">update</property>
        
        <!-- 显示SQL -->
        <property name="hibernate.show_sql">true</property>
        <!-- 格式化SQL -->
        <property name="hibernate.format_sql">true</property>
        
        <mapping resource="com/wangning/bean/Student.hbm.xml"/>
    </session-factory>


</hibernate-configuration>

分析：

<!DOCTYPE hibernate-configuration PUBLIC
 "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
 "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>

DTD----->这段代码可以从        

hibernate-core-5.1.9.Final.jar/org/hibernate/hibernate-configuration-3.0.dtd

路径下copy。同理映射文件中的dtd也相应加入。

package test;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.junit.Test;

import com.wangning.bean.Student;

public class Test1 {
@Test
    public  void mytest() {
        //加载主配置文件
        Configuration config=new Configuration().configure();
        //创建Session工厂
        SessionFactory sessionFactory=config.buildSessionFactory();
        //获取Session
        Session session=sessionFactory.getCurrentSession();
        session.getTransaction().begin();
        //执行操作        
        Student student =new Student("王五",21,100);
        session.save(student);
        session.getTransaction().commit();
    }


}

1、默认名字：hibernate.cfg.xml 是因为 new Configuration().configure()方法。如下定义：

    public static final String DEFAULT_CFG_RESOURCE_NAME = "hibernate.cfg.xml";
    public Configuration configure() throws HibernateException {
        return configure( StandardServiceRegistryBuilder.DEFAULT_CFG_RESOURCE_NAME );
    }

我们也可以更换名字为 wangwu.cfg.xml。只需在方法调用时 变更为

//加载主配置文件
        Configuration config=new Configuration().configure("wangwu.cfg.xml");