Hibernate初体验Cat之快速上手

Hibernate的手册里的Cat例子感觉很不明了，很难照着它轻松的运行起第一个例子，费了点周折，总算看到一点结果，如果你是新手，可以参考一下，少走一些弯路。

1.下载tomcat和Hibernate

• Tomcat 5.0.27
  http://apache.linuxforum.net/dist/jakarta/tomcat-5/v5.0.27/bin/jakarta-tomcat-5.0.27.zip
• Tomcat 5.0.28
  http://apache.linuxforum.net/dist/jakarta/tomcat-5/v5.0.28/bin/jakarta-tomcat-5.0.28.zip
• Hibernate2.1.6
  http://prdownloads.sourceforge.net/hibernate/?sort_by=date&sort=desc

2. 安装

以tomcat+mysql+hibernate为例

tomcat的安装，及mysql的安装和DBCP的配制参见http://blog.csdn.net/ahxu/archive/2004/09/01/91611.aspx，这里就不提了，这里假设tomcat+mysql已经配置并测试可用，这里%WebApp%代表你已配置好的一个web应用的root，着重说一下hibernate的安装，

1) 解压下载的压缩包，将解压出来的hibernate2.jar复制到%WebApp%/WEB-INF/lib

2) 将解压出来的lib目录下的

cglib-full-2.0.2.jar
commons-collections-2.1.1.jar
commons-logging-1.0.4.jar
dom4j-1.4.jar
ehcache-0.9.jar
jta.jar
log4j-1.2.8.jar
odmg-3.0.jar

文件同样复制到%WebApp%/WEB-INF/lib，具体请参见解压出来的lib目录下的readme.txt。

3) 将解压出来的etc目录下的

log4j.properties

文件复制到%WebApp%/WEB-INF/classes。

3.编写相关文件

1) 按照参考文档，配置hibernate，将以下代码保存为hibernate.cfg.xml放在%WebApp%/WEB-INF/classes下

<?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd"> <hibernate-configuration> <session-factory> <property name="connection.datasource">java:comp/env/jdbc/mysql</property> <property name="show_sql">false</property> <property name="dialect">net.sf.hibernate.dialect.MySQLDialect</property> <!-- Mapping files --> <mapping resource="Cat.hbm.xml"/> </session-factory> </hibernate-configuration>

NOTE：这里与hibernate文档里的不一样，这里指定数据源为mysql数据库jdbc/mysql，方言dialect为net.sf.hibernate.dialect.MySQLDialect。

2) 将以下代码保存为Cat.java，并生成相应的Cat.class，放入%WebApp%/WEB-INF/classes，这里无论你用什么方法生成Cat.class，但最终Cat.class应在%WebApp%/WEB-INF/classes/net/sf/hibernate/examples/quickstart目录下

package net.sf.hibernate.examples.quickstart; public class Cat { private String id; private String name; private char sex; private float weight; public Cat() { } public String getId() { return id; } private void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public char getSex() { return sex; } public void setSex(char sex) { this.sex = sex; } public float getWeight() { return weight; } public void setWeight(float weight) { this.weight = weight; } }

3) 将以下代码保存为O/R映射文件Cat.hbm.xml，放入%WebApp%/WEB-INF/classes

<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd"> <hibernate-mapping> <class name="net.sf.hibernate.examples.quickstart.Cat" table="CAT"> <!-- A 32 hex character is our surrogate key. It's automatically generated by Hibernate with the UUID pattern. --> <id name="id" type="string" unsaved-value="null" > <column name="CAT_ID" sql-type="char(32)" not-null="true"/> <generator class="uuid.hex"/> </id> <!-- A cat has to have a name, but it shouldn' be too long. --> <property name="name"> <column name="NAME" length="16" not-null="true"/> </property> <property name="sex"/> <property name="weight"/> </class> </hibernate-mapping

4) 在数据库内建表，结构如下

Column | Type | Modifiers --------+-----------------------+----------- cat_id | character(32) | not null name | character varying(16) | not null sex | character(1) | weight | real | Indexes: cat_pkey primary key btree (cat_id)

5) 将以下代码保存为HibernateUtil.java，并生成相应的HibernateUtil.class，放入%WebApp%/WEB-INF/classes，同样注意package

package net.sf.hibernate.examples.quickstart; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import net.sf.hibernate.*; import net.sf.hibernate.cfg.*; public class HibernateUtil { private static Log log = LogFactory.getLog(HibernateUtil.class); private static final SessionFactory sessionFactory; static { try { // Create the SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); } catch (Throwable ex) { log.error("Initial SessionFactory creation failed.", ex); throw new ExceptionInInitializerError(ex); } } public static final ThreadLocal session = new ThreadLocal(); public static Session currentSession() throws HibernateException { Session s = (Session) session.get(); // Open a new Session, if this Thread has none yet if (s == null) { s = sessionFactory.openSession(); session.set(s); } return s; } public static void closeSession() throws HibernateException { Session s = (Session) session.get(); session.set(null); if (s != null) s.close(); } }

NOTE:这里与hibernate文档也不同，原文档编绎时缺少2个包，这里已加上。

6) 将以下代码保存为test.jsp，放入%WebApp%/，用http测试

<%@ page language="java" pageEncoding="GB2312" %> <%@ page import="net.sf.hibernate.Transaction"%> <%@ page import="net.sf.hibernate.Session"%> <%@ page import="net.sf.hibernate.cfg.*"%> <%@ page import="net.sf.hibernate.Query"%> <%@ page import="net.sf.hibernate.examples.quickstart.HibernateUtil"%> <%@ page import="net.sf.hibernate.examples.quickstart.Cat"%> <%@ page import="java.util.*"%> <!DOCTYPE HTML PUBLIC "-//w3c//dtd html 4.0 transitional//en"> <html> <head> <title>Lomboz JSP</title> </head> <body bgcolor="#FFFFFF"> <% //添加一只Cat Session ses = HibernateUtil.currentSession(); Transaction tx= ses.beginTransaction(); Cat princess = new Cat(); princess.setName("ahxu"); princess.setSex('F'); princess.setWeight(7.4f); ses.save(princess); tx.commit(); HibernateUtil.closeSession(); //读取库里所有Cat ses = HibernateUtil.currentSession(); tx= ses.beginTransaction(); Query query = ses.createQuery("select c from Cat as c where c.sex = :sex"); query.setCharacter("sex", 'F'); for (Iterator it = query.iterate(); it.hasNext();) { Cat cat = (Cat) it.next(); out.println("Female Cat: " + cat.getName() ); } tx.commit(); HibernateUtil.closeSession(); %> </body> </html>

小结

步骤基本与原文档步骤相同，只是做了一些补充，方便上手，这里并没有对其中的一些配置做具体解释，如有疑问请参见发行包中的相关文档。

以上tomcat5.027 + hibernate2.1.6测试通过

附：

• Tomcat官方网站 http://jakarta.apache.org/tomcat/index.html
• Hibernate官方网站 http://www.hibernate.org
• Hibernamte非官方中文网 http://www.hibernate.org.cn
• mysql官方图形化管理工具Graphical clients -- different GUI interfaces to administer MySQL and data
  • MySQL Administrator
  • MySQL Query Browser
  • MySQL Control Center (no longer under development)