API或代码：Hibernate 3和4之间的区别？

Question

我已经粘贴了Hibernate 3配置文件SessionFactory类来配置这个配置。xml和带有JPA注释的bean。我想知道如果我使用的是Hibernate 4，那么在代码级别的上下文中会有什么变化，或者在外行语言中会有什么非常广泛的差异或进步。

hibernate.cfg.xml

    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="hibernate.connection.url">jdbc:oracle:thin:@192.168.2.144:1521:xe</property>
        <property name="hibernate.connection.username">prateek</property>
        <property name="connection.password">prateek</property>
        <property name="connection.pool_size">1</property>
        <property name="hibernate.dialect">org.hibernate.dialect.OracleDialect</property>
        <property name="show_sql">true</property>
        <property name="hbm2ddl.auto">create</property>
        <mapping class="com.vaannila.domain.User1" />
    </session-factory>
</hibernate-configuration>

用于建立连接的静态java类（SessionFactory Helper）

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class SessionFactoryHelper {
    private static final SessionFactory sessionFactory;

    static {
        try {            
            /*
             * Build a SessionFactory object from session-factory configuration 
             * defined in the hibernate.cfg.xml file. In this file we register 
             * the JDBC connection information, connection pool, the hibernate 
             * dialect that we used and the mapping to our hbm.xml file for each 
             * POJO (Plain Old Java Object).
             * 
             */
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable e) {
            System.err.println("Error in creating SessionFactory object." 
                + e.getMessage());
            throw new ExceptionInInitializerError(e);
        }
    }

    /*
     * A static method for other application to get SessionFactory object 
     * initialized in this helper class.
     * 
     */
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

豆类

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="USER1")
public class User1 {

    private Long id;
    private String name;
    private String gender;
    private String country;
    private String aboutYou;
    private Boolean mailingList;

    @Id
    @GeneratedValue
    @Column(name="USER_ID") 
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }

    @Column(name="USER_NAME")
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    @Column(name="USER_GENDER")
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }

    @Column(name="USER_COUNTRY")
    public String getCountry() {
        return country;
    }
    public void setCountry(String country) {
        this.country = country;
    }

    @Column(name="USER_ABOUT_YOU")
    public String getAboutYou() {
        return aboutYou;
    }
    public void setAboutYou(String aboutYou) {
        this.aboutYou = aboutYou;
    }

    @Column(name="USER_MAILING_LIST")
    public Boolean getMailingList() {
        return mailingList;
    }
    public void setMailingList(Boolean mailingList) {
        this.mailingList = mailingList;
    }

}

Answer 1

文件hibernate.cfg。xml很好。hibernate-configuration-3.0.dtd中的版本仍然是3.0，这看起来可能令人困惑，但事实就是这样。dtd没有更新。也许您想使用以hibernate为前缀的名称，例如，hibernate。显示sql，而不是显示sql。属性的名称可以从文档中找到。通常使用的DTD\U位置是<代码>http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd（vs…sourceforge…），但两者都应该有效。

从API中可以看到，buildSessionFactory已被弃用。这是它在4.x中的构建方式：

Configuration conf = new Configuration();
conf.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(conf.getProperties()).buildServiceRegistry();        
sessionFactory = configuration.buildSessionFactory(serviceRegistry);

在留档的许多地方，这仍然不是最新的。

通常，不需要更改bean类中的映射。原因是您使用的是普通的JPA映射，Hibernate 3也是JPA规范中描述的实现。