Build Hibernate Applications

By Known-Space -

Hibernate

What is Hibernate?

 • A framework for persisting / saving Java objects in a database

Benefits of Hibernate

 • Hibernate handles all of the low-level SQL
• Minimizes the amount of JDBC code you have to develop
• Hibernate provides the Object-to-Relational Mapping (ORM)

Hibernate and JDBC

 • Hibernate uses JDBC for all database communications

 SET UP YOUR ENVIRONMENT

 Required Software

 To Build Hibernate Applications, you need the following:
1. Java Integrated Development Environment (IDE)
2. Database Server
3. Hibernate JAR files and JDBC Driver

Setup Hibernate in Eclipse:
1. Create Eclipse Project
2. Download Hibernate Files
3. Download MySQL JDBC Driver
4. Add JAR files to Eclipse Project … Build Path

Testing The JDBC Connection

 Create class for TestJdbc

 package com.luv2code.com.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;

 public class TestJdbc {

 public static void main(String[] args) {

String jdbcUrl = "jdbc:mysql://localhost:3306/hb_student_tracker?  useSSL=false&serverTimezone-UTC";
String user = "hbstudent";
String pass = "hbstudent";

try {
System.out.println("Connecting to database : "+ jdbcUrl);
Connection myConn = DriverManager.getConnection(jdbcUrl,user,pass);
System.out.println("Connection Successfull : "+ myConn);

} catch (Exception e) {
e.printStackTrace();
}
}
}

Hibernate Development Process

1. Add Hibernate Configuration file
2. Annotate Java Class
3. Develop Java Code to perform database operations

Hibernate Configuration file (hibernate.cfg.xml)


<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <!-- JDBC Database connection settings -->
        <property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hb_student_tracker?useSSL=false&amp;serverTimezone=UTC</property>
        <property name="connection.username">hbstudent</property>
        <property name="connection.password">hbstudent</property>

        <!-- JDBC connection pool settings ... using built-in test pool -->
        <property name="connection.pool_size">1</property>

        <!-- Select our SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Echo the SQL to stdout -->
        <property name="show_sql">true</property>

<!-- Set the current session context -->
<property name="current_session_context_class">thread</property>
    </session-factory>
</hibernate-configuration>

Develop Java Code to perform database operations

Entity Class  : Java class that is mapped to a database table

Object-To-Relational Mapping (ORM) : The developer defines mapping between Java class and database table
Two Options for Mapping:

  1.  Option 1: XML config file (legacy)
  2.  Option 2: Java Annotations (modern, preferred)
    1. Step 1: Map class to database table
    2. Step 2: Map fields to database columns

Step 1: Map class to database table


Step 2: Map fields to database columns
Two key Players
Java Code Setup

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