Java Hibernate 5.3.x

本文介绍如何使用Hibernate根据实体类和映射文件自动生成数据库表结构。通过配置hibernate.cfg.xml文件,设置连接信息和映射关系,利用TestStudents测试类中的SchemaExport方法实现表结构的生成。

SchemeExport

  Hibernate根据实体类和实体类映射文件自动生成表结构。

  示例代码:

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="connection.url">jdbc:mysql://172.16.65.200:3306/hibernate?useUnicode=true&amp;characterEncoding=UTF8</property>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.username">root</property>
        <property name="connection.password">123456</property>
        <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>

        <property name="hbm2ddl.auto">create</property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>
        <property name="hibernate.current_session_context_class">thread</property>

        <mapping class="com.entity.Students" />
    </session-factory>
</hibernate-configuration>
hibernate.cfg.xml
package com.entity;

import javax.persistence.Entity;    //JPA注解
import javax.persistence.Id;
import java.util.Date;

@Entity
public class Students {

    private int sid; // 学号
    private String name;    // 姓名
    private String gender;  // 性别
    private Date birthday;  // 出生日期
    private String major;   // 专业
    private String address; // 地址

    public Students(){

    }

    @Id
    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Students{" +
                "sid=" + sid +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", birthday=" + birthday +
                ", major='" + major + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}
Students实体类
package com.entity;

import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.hibernate.tool.schema.TargetType;
import org.junit.jupiter.api.Test;

import java.util.EnumSet;

public class TestStudents {

    @Test
    public void testSchemaExport(){
        // 创建服务注册对象
        StandardServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
        // 生成Metadata
        Metadata metadata = new MetadataSources(serviceRegistry).buildMetadata();
        // 生成表结构
        SchemaExport schemaExport = new SchemaExport();
        schemaExport.create(EnumSet.of(TargetType.DATABASE), metadata);
    }
}
TestStudents测试类

 

Session

  openSession

    每次打开一个新的Session会话

  getCurrentSession

    始终是一个Session会话,类似工厂方法

    需要在hibernate.cfg.xml文件中添加配置:<property name="hibernate.current_session_context_class">thread</property>

 

主键自增

  1、在主键配置中增加native

    <id name="sid" column="sid">

      <generator class="native"/>

    </id>

  2、通过Annotation方式   

     @GeneratedValue(strategy = GenerationType.IDENTITY) // 表示将主键设置为auto_increment

  3、JPA提供的四种标准用法为TABLE、SEQUENCE、IDENTITY、AUTO
    TABLE:使用一个特定的数据库表格来保存主键。 
    SEQUENCE:根据底层数据库的序列来生成主键,条件是数据库支持序列。 
    IDENTITY:主键由数据库自动生成(主要是自动增长型)。 
    AUTO:主键由程序控制,在指定主键时,如果不指定主键生成策略,默认为AUTO。

 

Column注解 

  @Entity 实体类,映射为一个表。

  @Column 可将属性映射到列,使用该注解来覆盖默认值。

    常用属性:

    name: 可选,表示数据库表中该字段的名称,默认和属性名称一致。

    nullable: 可选,一波啊是该字段是否允许为null,默认为true。

    unique: 可选,表示该字段是否是唯一标识,默认为false。

    length: 可选,表示该字段大小,仅对String类型的字段有效。

  @ManyToOne  多对一映射

  @OneToMany  一对多映射

  @ManyToMany 多对多映射

 

Fetch和CasCade

  FetchType.LAZY:懒加载,加载一个实体时,定义懒加载的属性不会马上从数据库中加载

  FetchType.EAGER:急加载,加载一个实体时,定义急加载的属性会立即从数据库中加载

  CascadeType.REFRESH:级联刷新,当多个用户同时作操作一个实体,为了用户取到的数据是实时的,在用实体中的数据之前就可以调用一下refresh()方法!

  CascadeType.REMOVE:级联删除,当调用remove()方法删除Order实体时会先级联删除OrderItem的相关数据!

  CascadeType.MERGE:级联更新,当调用了Merge()方法,如果Order中的数据改变了会相应的更新OrderItem中的数据,

  CascadeType.PERSIST:级联保存,当调用了Persist() 方法,会级联保存相应的数据,

  CascadeType.ALL:包含以上所有级联属性。

 

http://docs.jboss.org/hibernate/orm/5.3/userguide/html_single/Hibernate_User_Guide.html

转载于:https://www.cnblogs.com/vincenshen/p/10241815.html

提示报错org.springframework.beans.factory.BeanCreationException: Error creating bean with name &#39;entityManagerFactory&#39; defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.cache.spi.RegionFactory] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1804) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1168) ~[spring-context-5.3.31.jar:5.3.31] at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:919) ~[spring-context-5.3.31.jar:5.3.31] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:591) ~[spring-context-5.3.31.jar:5.3.31] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.18.jar:2.7.18] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:732) [spring-boot-2.7.18.jar:2.7.18] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:409) [spring-boot-2.7.18.jar:2.7.18] at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) [spring-boot-2.7.18.jar:2.7.18] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1300) [spring-boot-2.7.18.jar:2.7.18] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1289) [spring-boot-2.7.18.jar:2.7.18] at com.hxl.bi.BiApplication.main(BiApplication.java:30) [classes/:na] Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.cache.spi.RegionFactory] at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:284) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:246) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:223) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.internal.MetadataBuilderImpl$MetadataBuildingOptionsImpl.<init>(MetadataBuilderImpl.java:713) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.internal.MetadataBuilderImpl.<init>(MetadataBuilderImpl.java:123) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.MetadataSources.getMetadataBuilder(MetadataSources.java:158) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.<init>(EntityManagerFactoryBuilderImpl.java:250) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.<init>(EntityManagerFactoryBuilderImpl.java:182) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:52) ~[spring-orm-5.3.31.jar:5.3.31] at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.3.31.jar:5.3.31] at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409) ~[spring-orm-5.3.31.jar:5.3.31] at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396) ~[spring-orm-5.3.31.jar:5.3.31] at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) ~[spring-beans-5.3.31.jar:5.3.31] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.31.jar:5.3.31] ... 16 common frames omitted Caused by: org.hibernate.boot.registry.selector.spi.StrategySelectionException: Unable to resolve name [org.hibernate.cache.jcache.JCacheRegionFactory] as strategy [org.hibernate.cache.spi.RegionFactory] at org.hibernate.boot.registry.selector.internal.StrategySelectorImpl.selectStrategyImplementor(StrategySelectorImpl.java:156) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.registry.selector.internal.StrategySelectorImpl.resolveStrategy(StrategySelectorImpl.java:239) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.registry.selector.internal.StrategySelectorImpl.resolveStrategy(StrategySelectorImpl.java:192) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.cache.internal.RegionFactoryInitiator.resolveRegionFactory(RegionFactoryInitiator.java:93) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.cache.internal.RegionFactoryInitiator.initiateService(RegionFactoryInitiator.java:47) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.cache.internal.RegionFactoryInitiator.initiateService(RegionFactoryInitiator.java:32) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:272) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] ... 30 common frames omitted Caused by: org.hibernate.boot.registry.classloading.spi.ClassLoadingException: Unable to load class [org.hibernate.cache.jcache.JCacheRegionFactory] at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:133) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at org.hibernate.boot.registry.selector.internal.StrategySelectorImpl.selectStrategyImplementor(StrategySelectorImpl.java:152) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] ... 37 common frames omitted Caused by: java.lang.ClassNotFoundException: Could not load requested class : org.hibernate.cache.jcache.JCacheRegionFactory at org.hibernate.boot.registry.classloading.internal.AggregatedClassLoader.findClass(AggregatedClassLoader.java:210) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] at java.lang.ClassLoader.loadClass(ClassLoader.java:419) ~[na:1.8.0_432] at java.lang.ClassLoader.loadClass(ClassLoader.java:352) ~[na:1.8.0_432] at java.lang.Class.forName0(Native Method) ~[na:1.8.0_432] at java.lang.Class.forName(Class.java:348) ~[na:1.8.0_432] at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:130) ~[hibernate-core-5.6.15.Final.jar:5.6.15.Final] ... 38 common frames omitted
07-26
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