Hiberate 内存数据库

1. 内存数据库实现
2. Hibernate 内存数据库示例
3. 项目结构和依赖项
- 3.1 pom.xml

原文： https://howtodoinjava.com/hibernate/hibernate-4-using-in-memory-database-with-hibernate/

在我们工作的组织中，朋友经常不允许甚至访问必要的开发人员工具，例如本地数据库安装。这也可能是由于相当正当的原因（有时似乎只是荒谬的）。在此 Hiberate 内存数据库教程中，我提供了一个无需安装任何数据库即可测试您的 Hiberate 代码的示例。

这可以帮助您编写应用的单元测试用例，因为某些架构师将数据库访问视为依赖。

1. 内存数据库实现

1.1 Maven 依赖

<dependency>  
    <groupId>hsqldb</groupId>  
    <artifactId>hsqldb</artifactId>  
    <version>1.8.0.10</version>  
</dependency>

1.2 获取数据库连接

对于此示例，我使用 HSQLDB 数据库通过我们的 Hiberate 代码创建和访问内存数据库。如果您使用简单的简单 JDBC，则可以直接使用下面的语句访问内存数据库。

Connection c = DriverManager.getConnection("jdbc:hsqldb:mem:howtodoinjava", "sa", "");

这里要注意的主要事情是“mem:howtodoinjava”。这里mem表示使用内存数据库，而不是任何物理数据库。

1.3 需要默认的用户名和密码

请注意，尽管您将必须提供默认的用户名“sa”和一个空白密码才能连接到数据库，否则将出现以下异常。

Caused by: java.sql.SQLException: Access is denied
    at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
    at org.hsqldb.jdbc.jdbcConnection.<init>(Unknown Source)
    at org.hsqldb.jdbcDriver.getConnection(Unknown Source)
    at org.hsqldb.jdbcDriver.connect(Unknown Source)
    at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:55)
    ... 15 more

2. Hibernate 内存数据库示例

现在，在下面的源代码文件中查找使用 hibernate 进行内存数据库访问的示例。

2.1 `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.archive.autodetection">class,hbm</property>  
           <property name="hibernate.dialect">org.hibernate.dialect.HSQLDialect</property>  
           <property name="hibernate.show_sql">true</property>    
           <property name="hibernate.connection.driver_class">org.hsqldb.jdbcDriver</property>    
           <property name="hibernate.connection.username">sa</property>    
           <property name="hibernate.connection.password"></property>    
           <property name="hibernate.connection.url">jdbc:hsqldb:mem:howtodoinjava</property>    
           <property name="hibernate.hbm2ddl.auto">create</property>    
           <mapping class="com.howtodoinjava.demo.entity.EmployeeEntity"></mapping>
    </session-factory>
</hibernate-configuration>

2.2. `HibernateUtil.java`

package com.howtodoinjava.demo.util;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class HibernateUtil
{
   private static SessionFactory sessionFactory = buildSessionFactory();
   private static SessionFactory buildSessionFactory()
   {
      try
      {
         if (sessionFactory == null)
         {
            Configuration configuration = new Configuration().configure(HibernateUtil.class.getResource("/hibernate.cfg.xml"));
            StandardServiceRegistryBuilder serviceRegistryBuilder = new StandardServiceRegistryBuilder();
            serviceRegistryBuilder.applySettings(configuration.getProperties());
            ServiceRegistry serviceRegistry = serviceRegistryBuilder.build();
            sessionFactory = configuration.buildSessionFactory(serviceRegistry);
         }
         return sessionFactory;
      } catch (Throwable ex)
      {
         System.err.println("Initial SessionFactory creation failed." + ex);
         throw new ExceptionInInitializerError(ex);
      }
   }
   public static SessionFactory getSessionFactory()
   {
      return sessionFactory;
   }
   public static void shutdown()
   {
      getSessionFactory().close();
   }
}

2.3. `EmployeeEntity.java`

package com.howtodoinjava.demo.entity;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
@Entity
@org.hibernate.annotations.Entity(dynamicUpdate = true)
@Table(name = "Employee", uniqueConstraints = {@UniqueConstraint(columnNames = "ID"), @UniqueConstraint(columnNames = "EMAIL")})
public class EmployeeEntity implements Serializable
{
   private static final long serialVersionUID = -1798070786993154676L;
   @Id
   @Column(name = "ID", unique = true, nullable = false)
   private Integer           employeeId;
   @Column(name = "EMAIL", unique = true, nullable = false, length = 100)
   private String            email;
   @Column(name = "FIRST_NAME", unique = false, nullable = false, length = 100)
   private String            firstName;
   @Column(name = "LAST_NAME", unique = false, nullable = false, length = 100)
   private String            lastName;
   public Integer getEmployeeId()
   {
      return employeeId;
   }
   public void setEmployeeId(Integer employeeId)
   {
      this.employeeId = employeeId;
   }
   public String getEmail()
   {
      return email;
   }
   public void setEmail(String email)
   {
      this.email = email;
   }
   public String getFirstName()
   {
      return firstName;
   }
   public void setFirstName(String firstName)
   {
      this.firstName = firstName;
   }
   public String getLastName()
   {
      return lastName;
   }
   public void setLastName(String lastName)
   {
      this.lastName = lastName;
   }
}

现在测试上面的代码。

2.4. `TestHibernate.java`

package com.howtodoinjava.test;
import org.hibernate.Session;
import com.howtodoinjava.demo.entity.EmployeeEntity;
import com.howtodoinjava.demo.util.HibernateUtil;
public class TestHibernate
{
   public static void main(String[] args)
   {
      Session session = HibernateUtil.getSessionFactory().openSession();
      session.beginTransaction();
      // Add new Employee object
      EmployeeEntity emp = new EmployeeEntity();
      emp.setEmployeeId(1);
      emp.setEmail("demo-user@mail.com");
      emp.setFirstName("demo");
      emp.setLastName("user");
      session.save(emp);
      session.getTransaction().commit();
      HibernateUtil.shutdown();
   }
}
Output:
Hibernate: drop table Employee if exists
Hibernate: create table Employee (ID integer not null, EMAIL varchar(100) not null, FIRST_NAME varchar(100) not null, LAST_NAME varchar(100) not null, primary key (ID))
Hibernate: alter table Employee add constraint UK_ardf0f11mfa6tujs3hflthwdv  unique (EMAIL)
Hibernate: insert into Employee (EMAIL, FIRST_NAME, LAST_NAME, ID) values (?, ?, ?, ?)

3. 项目结构和依赖项

以下是此示例的项目结构。

Hiberate 内存数据库 - 图1

如果在设置本示例的 maven 依赖项方面需要任何帮助，请遍历pom.xml文件。

3.1 `pom.xml`

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd;
  <modelVersion>4.0.0</modelVersion>
  <groupId>ABC</groupId>
  <artifactId>ABC</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.3.2</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
      <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <!-- for JPA, use hibernate-entitymanager instead of hibernate-core -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <!-- optional -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-osgi</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-envers</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-c3p0</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-proxool</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-infinispan</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-ehcache</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
      <dependency>
        <groupId>antlr</groupId>
        <artifactId>antlr</artifactId>
        <version>2.7.6</version>
    </dependency>
    <dependency>
        <groupId>commons-collections</groupId>
        <artifactId>commons-collections</artifactId>
        <version>3.1</version>
    </dependency>
    <dependency>
        <groupId>dom4j</groupId>
        <artifactId>dom4j</artifactId>
        <version>1.6.1</version>
    </dependency>
    <dependency>
        <groupId>javassist</groupId>
        <artifactId>javassist</artifactId>
        <version>3.4.GA</version>
    </dependency>
    <dependency>
        <groupId>javax.transaction</groupId>
        <artifactId>jta</artifactId>
        <version>1.1</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.5.6</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.5.6</version>
    </dependency>
    <dependency>  
        <groupId>hsqldb</groupId>  
        <artifactId>hsqldb</artifactId>  
        <version>1.8.0.10</version>  
    </dependency>
  </dependencies>
</project>

这就是有关将内存数据库与 Hibernate 结合使用的快速教程的全部内容。

学习愉快！

1. 内存数据库实现

1.1 Maven 依赖

1.2 获取数据库连接

1.3 需要默认的用户名和密码

2. Hibernate 内存数据库示例

2.1 hibernate.cfg.xml

2.2. HibernateUtil.java

2.3. EmployeeEntity.java