22.02. Understanding Hibernate Configuration

Understanding Hibernate Configuration


This tutorial deals with Understanding Hibernate Configuration. As we have introduced Hibernate in our previous video, we now go deep into understanding the configuration file where we understand the functions of various files and classes such as the driver class, the dialect class which prepares the query in the background, and many more. This will be seen in depth in the upcoming videos.

ImageUpload.java

Explanation:

In this program, the Servlet handles uploading image files from a client’s browser to the server.

The program uses the Apache Commons FileUpload library to handle the file-uploading process. In the doPost method, the ServletFileUpload object is created using a DiskFileItemFactory object as its constructor parameter. The DiskFileItemFactory is used to configure various properties of the file upload process, such as the size threshold at which files should be written to disk and the directory where uploaded files should be stored.

The program then attempts to parse the request using the parseRequest method of the ServletFileUpload object. This method returns a list of FileItem objects, each of which represents an uploaded file.

The program then iterates over the list of FileItem objects and processes each file. For each file, the program retrieves the file name using the getName method of the FileItem object. The file name may include the full path of the file on the client’s machine, so the program attempts to extract just the file name using the substring method.

The program then writes the file to the server’s file system using the write method of the FileItem object, specifying the directory where the file should be stored. In this example, the directory used is “c:/images/”.

If any errors occur during the file upload process, the program catches the exception and prints a stack trace to the console.

hibernate.cfg.xml

Explanation:

This is an XML configuration file for the Hibernate framework, which is an ORM tool used to map Java objects to relational database tables. The file defines the Hibernate Configuration DTD 3.0 and contains configuration properties for the Hibernate session factory.

These include database connection settings, such as the driver class, dialect, URL, username, and password. The show_sql property logs all SQL statements generated by Hibernate to the console for debugging.

The current_session_context_class property is set to thread, which is the recommended approach for managing the Hibernate session in a multi-threaded environment.

Overall, this file establishes a connection to a MySQL database and configures the Hibernate session factory to use it.

index.jsp

Contributed by: Salim Sheikh

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