Hello people!
I'm begin in the world of database persistence and i'm lost.... help!
My english isn't so good (i'm brazilian) but i will try to explain
In the section quickstart of the manual I don't understand how cat.class and
cat.hbm.xml work (I understand the structure, but i don't know how show my
db
Follow my files:
------------ cat.java
public class Cat {
private String id;
private String name;
private char sex;
private float weight;
public Cat() {
}
public String getId() {
return id;
}
public 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;
}
}
-----------------------
------------------ cat.hbm.xml
<?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="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" sql-type="varchar(16)" not-null="true"/>
</property>
<property name="sex"/>
<property name="weight"/>
</class>
</hibernate-mapping>
--------------------
-------- hibernate.cfg.xml
<?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/quickstart</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>
---------------------------
------------- hibernate.properties
hibernate.dialect net.sf.hibernate.dialect.MySQLDialect
hibernate.connection.driver_class org.gjt.mm.mysql.Driver
hibernate.connection.driver_class com.mysql.jdbc.Driver
hibernate.connection.url jdbc:mysql:/localhost/quickstart
hibernate.connection.username root
hibernate.connection.password
------------------------------
--------- hiernateutil.java
import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.ServletException;
import java.util.*;
import java.io.IOException;
import java.io.PrintWriter;
public class HibernateUtil
extends HttpServlet {
private SessionFactory sessionFactory;
private Session session;
private Transaction transaction;
public void doGet(HttpServletRequest request, HttpServletResponse
response)
throws ServletException, IOException {
try {
// Initialize Hibernate (Configuration and SessionFactory)
initHibernate();
// Prepare out
response.setContentType("text/html");
PrintWriter out = response.getWriter();
// Create some Cats
beginTransaction();
createCats(out);
endTransaction(true);
// Select all Cats
beginTransaction();
selectAllCats(out);
endTransaction(false);
// Select female Cats
beginTransaction();
selectFemaleCats(out);
endTransaction(false);
} catch (HibernateException e) {
throw new ServletException(e);
}
}
public void createCats(PrintWriter out)
throws HibernateException {
out.print("<h3>Creating Cats:</h3>");
out.println("CREATING 'Princess'...<br/>");
Cat princess = new Cat();
princess.setName("Princess");
princess.setSex('F');
princess.setWeight(7.4f);
session.save(princess);
out.println("CREATING 'Max'...<br/>");
Cat max = new Cat();
max.setName("Max");
max.setSex('M');
max.setWeight(8.1f);
session.save(max);
out.println("CREATING 'Sophie'...<br/>");
Cat sophie = new Cat();
sophie.setName("Sophie");
sophie.setSex('F');
sophie.setWeight(4.1f);
session.save(sophie);
}
public void selectAllCats(PrintWriter out)
throws HibernateException {
out.print("<h3>Retrieving all Cats:</h3>");
String queryString = "select cat from Cat as cat";
Query query = session.createQuery(queryString);
for (Iterator it = query.iterate(); it.hasNext();) {
Cat cat = (Cat) it.next();
out.println("CAT: " + cat.getName() + " (" + cat.getSex() + ", "
+ cat.getWeight() + ")<br/>");
}
}
public void selectFemaleCats(PrintWriter out)
throws HibernateException {
out.print("<h3>Retrieving female Cats:</h3>");
String queryString = "select cat from Cat as cat where cat.sex =
:sex";
Query query = session.createQuery(queryString);
query.setCharacter("sex", 'F');
for (Iterator it = query.iterate(); it.hasNext();) {
Cat cat = (Cat) it.next();
out.println("CAT: " + cat.getName() + " (" + cat.getSex() + ", "
+ cat.getWeight() + ")<br/>");
}
}
// Helper Methods
private void initHibernate()
throws HibernateException {
// Load Configuration and build SessionFactory
sessionFactory = new
Configuration().configure().buildSessionFactory();
}
private void beginTransaction()
throws HibernateException {
session = sessionFactory.openSession();
transaction = session.beginTransaction();
}
private void endTransaction(boolean commit)
throws HibernateException {
if (commit) {
transaction.commit();
} else {
// Don't commit the transaction, can be faster for read-only
operations
transaction.rollback();
}
session.close();
}
}
--------------------------
All these files are in the C:\Tomcat\webapps\quickstart\WEB-INF\classes
I'm sorry if the questions are so easy, but I don't find any example step by
step
Thanks a lot
Fabio Esposito
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