【学习笔记】Hibernate连接oracle数据库
一、 Hibernate介绍
Hibernate是基于对象/关系映射（ORM，Object/Relational Mapping）的一个解决方案。ORM方案的思想是将对象模型表示的对象映射到关系型数据库中，或者反之。Hibernate目前是ORM思想在Java中最成功、最强大的实现。它于2001年的年末发布第一个版本，立即引起了广泛的注意。2003年6月，Hibernate2发表，并且获得Jolt大奖，进而被JBoss吸纳成为它的一个子项目。2005年3月，Hibernate 3发表，其中做了一些比较重大的改进。本文以Hibernate5为基础编写。
另外，Hibernate除了可以在J2EE容器中运行外，还可以运行在Java应用程序中。本文就是以Java应用程序为例来介绍它。
二、配置开发环境
本文以一个Java应用程序（Java Application）为例，介绍如何使用Hibernate来进行数据库操作。
在进行Hibernate开发之前，需要首先获得Hibernate类库、相应数据库的JDBC驱动类库。Hibernate类库可以从http://www.hibernate.org中下载。我用的Hibernate版本是5.3.2。而JDBC驱动可以根据不同的数据库来选择，在这个例子中，使用的是Oracle数据库，那么相应的JDBC驱动可以从Oracle安装目录\ora92\jdbc下获得。其他的数据库请根据相关的说明获得。
下载Hibernate包后，可以将它解压到一个文件夹，此处假设为C:\hibernate-release-5.3.2.Final，然后将C:\hibernate-release-5.3.2.Final\lib\required下的jar包复制到项目的lib文件夹下。(一般只需要dom4j、cglig、commons-logging、commons-collections、log4j、ehcache、asm、jta、antlr这些类库就可以了）
还需要一个Oracle驱动jar包。
做完这些配置后，就可以在此基础上进行基于Hibernate的Java程序开发了。
三、开发基于Hibernate的应用
这里我用的是Oracle自带的Emp表测试。
1.首先配置一个hibernate.cfg.xml来指定Hibernate所使用的数据库以及用户名、密码等其他相关的配置，我们在此使用xml文件，它的内容如下：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 配置数据库的基本信息 -->
<!--数据库连接url-->
<property name="connection.url">jdbc:oracle:thin:@localhost:1521:gy</property>
<!--连接数据库的Driver-->
<property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<!--用户名-->
<property name="connection.username">scott</property>
<!--密码-->
<property name="connection.password">admin</property>
<!-- 配置hibernate指定数据库的方言 -->
<property name="dialect">org.hibernate.dialect.Oracle9Dialect</property>
<!-- 配置hibernate的基本信息 -->
<!-- 打印sql语句到控制台 -->
<property name="show_sql">true</property>
<!-- 格式化sql语句 -->
<property name="format_sql">true</property>
<!-- 指定自动生成数据表的策略 -->
<property name="hbm2ddl.auto">update</property>
<!-- 配置映射文件 -->
<mapping resource="com/guyun/test/emp.hbm.xml"/>
</session-factory>
</hibernate-configuration>2.封装一个Emp实体类
import java.util.Date;
/**
* 员工实体类
*/
public class Emp {
private int empno;
private String ename;
private String job;
private Date hiredate;
public Emp() {
super();
}
//这里的构造器没有empno
public Emp(String ename, String job, Date hiredate) {
super();
this.ename = ename;
this.job = job;
this.hiredate = hiredate;
}
public int getEmpno() {
return empno;
}
public void setEmpno(int empno) {
this.empno = empno;
}
public String getEname() {
return ename;
}
public void setEname(String ename) {
this.ename = ename;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public Date getHiredate() {
return hiredate;
}
public void setHiredate(Date hiredate) {
this.hiredate = hiredate;
}
@Override
public String toString() {
return "Emp [empno=" + empno + ", ename=" + ename + ", job=" + job + ", hiredate=" + hiredate + "]";
}
}3.配置emp.hbm.xml映射文件
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<!-- name对应实体类 ,table对应数据库表名 -->
<class name="com.guyun.entity.Emp" table="emp">
<!-- 主键 -->
<id name="empno" column="empno" type="int">
<!-- 采用算法为主键自动设置值，配置之后就不用为主键设置值（配置这个之后自已设置的主键值将不采用） -->
<generator class="increment"></generator>
</id>
<!-- name对应Emp.java里字段名称，column对应数据库的列名 ，type对应字段类型 -->
<property name="ename" column="ename" type="java.lang.String"></property>
<property name="job" column="job" type="java.lang.String"></property>
<property name="hiredate" column="hiredate" type="java.sql.Date"></property>
</class>
</hibernate-mapping>4.最后编写测试类
import java.sql.Date;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import com.guyun.entity.Emp;
public class EmpTest {
public static void main(String[] args) {
//创建一个sessionFactory对象
SessionFactory factory = new Configuration().configure().buildSessionFactory();
//创建一个session
Session session = factory.openSession();
//开启事务
Transaction transaction = session.beginTransaction();
//执行插入数据库
Emp emp = new Emp("孤云","Boss",new Date(0));//这里不设置主键是因为在映射文件中配置了自动设置主键
session.save(emp);
//提交事务
transaction.commit();
//关闭session
session.close();
//关闭sessionFactory
factory.close();
}
}
最后是控制台输出的结果
Hibernate: select max(empno) from emp 这是生成的主键
Hibernate: insert into emp (ename, job, hiredate, empno) values (?, ?, ?, ?) 这是插入语句，最后数据库也成功插入了一条数据
在测试的过程中遇到了一个异常ServiceException，经查找发现是配置数据库url的时候把localhost写成了location，导致数据库连接不上。
附上异常信息：
ERROR: The Network Adapter could not establish the connection
Exception in thread "main" org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:275)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214)
at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214)
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:179)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:119)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:84)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:474)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:85)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:689)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:724)
at com.guyun.test.EmpTest.main(EmpTest.java:15)
Caused by: org.hibernate.exception.GenericJDBCException: Error calling Driver#connect
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.convertSqlException(BasicConnectionCreator.java:118)
at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:41)
at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.createConnection(BasicConnectionCreator.java:58)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.addConnections(DriverManagerConnectionProviderImpl.java:363)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.<init>(DriverManagerConnectionProviderImpl.java:282)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.<init>(DriverManagerConnectionProviderImpl.java:260)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections$Builder.build(DriverManagerConnectionProviderImpl.java:401)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildPool(DriverManagerConnectionProviderImpl.java:112)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:75)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:100)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:246)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:145)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:94)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263)
... 14 more
Caused by: java.sql.SQLException: The Network Adapter could not establish the connection
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:412)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:531)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:221)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:503)
at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:38)
... 29 more
Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:359)
at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:422)
at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:672)
at oracle.net.ns.NSProtocol.connect(NSProtocol.java:237)
at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1042)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:301)
... 34 more
Caused by: java.net.UnknownHostException: location
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
at java.net.InetAddress.getAllByName(InetAddress.java:1192)
at java.net.InetAddress.getAllByName(InetAddress.java:1126)
at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:114)
at oracle.net.nt.ConnOption.connect(ConnOption.java:123)
at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:337)
... 39 more最后附上Hibernate和Oracle驱动包的下载连接：链接：https://pan.baidu.com/s/1ZC9b2r4xZGIwK_L6DYmM0A 密码：z8l6
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