国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Home Java javaTutorial What is the ORM mechanism of Java Hibernate framework?

What is the ORM mechanism of Java Hibernate framework?

Apr 17, 2024 pm 02:39 PM
java orm data access

Hibernate is a Java ORM framework used to establish mapping between Java objects and relational databases. Its ORM mechanism includes the following steps: Annotation/Configuration: The object class is marked with annotations or XML files, specifying its mapped database tables and columns. Session factory: manages the connection between Hibernate and the database. Session: Represents an active connection to the database and is used to perform query and update operations. Persistence: Save data to the database through the save() or update() method. Query: Use Criteria and HQL to define complex queries to retrieve data.

Java Hibernate 框架的 ORM 機(jī)制是什么？

Java Hibernate Framework ORM Mechanism

Introduction

Hibernate is a popular Java Object Relational Mapping (ORM) framework that allows seamless mapping between Java objects and relational databases. The role of an ORM is to manage the process of converting object state into database records and vice versa, simplifying the development and maintenance of data access code.

ORM mechanism

Hibernate uses Java annotations or XML configuration files to define the mapping of objects to database tables. It implements ORM through the following key steps:

  • Annotation/Configuration: Object classes use Hibernate annotations (such as @Entity, @Table) or XML configuration file to specify which table and column in the database it maps to.
  • Session Factory: The session factory manages the connection between Hibernate and the database.
  • Session: A session represents an active connection to the database and is used to perform query and update operations.
  • Persistence: To save data to the database, the object must be persisted through the save() or update() method.
  • Query: Criteria and HQL (Hibernate query language) are used to define complex queries and retrieve data.

Practical case

We create a Java class Employee to represent the employee table in the database: 

@Entity
@Table(name = "employees")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String name;
    private int salary;

    // 省略getter、setter和構(gòu)造方法
}

In the main() method, we use the Hibernate configuration file (hibernate.cfg.xml) to create a session factory, open a session, and save an Employee object , and retrieve all employees: 

public static void main(String[] args) {
    // 創(chuàng)建會(huì)話(huà)工廠(chǎng)
    SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

    // 打開(kāi)會(huì)話(huà)
    Session session = sessionFactory.openSession();
    session.beginTransaction();

    // 保存一個(gè)Employee對(duì)象
    Employee employee = new Employee();
    employee.setName("John Doe");
    employee.setSalary(10000);
    session.save(employee);

    // 查詢(xún)所有Employee對(duì)象
    List<Employee> employees = session.createQuery("from Employee", Employee.class).list();

    // 打印員工信息
    for (Employee emp : employees) {
        System.out.println(emp.getName() + " - " + emp.getSalary());
    }

    // 提交事務(wù)并關(guān)閉會(huì)話(huà)
    session.getTransaction().commit();
    session.close();
}

The above is the detailed content of What is the ORM mechanism of Java Hibernate framework?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Selecting Specific Columns | Performance Optimization Selecting Specific Columns | Performance Optimization Jun 27, 2025 pm 05:46 PM

Selectingonlyneededcolumnsimprovesperformancebyreducingresourceusage.1.Fetchingallcolumnsincreasesmemory,network,andprocessingoverhead.2.Unnecessarydataretrievalpreventseffectiveindexuse,raisesdiskI/O,andslowsqueryexecution.3.Tooptimize,identifyrequi

What is the `enum` type in Java? What is the `enum` type in Java? Jul 02, 2025 am 01:31 AM

Enums in Java are special classes that represent fixed number of constant values. 1. Use the enum keyword definition; 2. Each enum value is a public static final instance of the enum type; 3. It can include fields, constructors and methods to add behavior to each constant; 4. It can be used in switch statements, supports direct comparison, and provides built-in methods such as name(), ordinal(), values() and valueOf(); 5. Enumeration can improve the type safety, readability and flexibility of the code, and is suitable for limited collection scenarios such as status codes, colors or week.

Applying Semantic Structure with article, section, and aside in HTML Applying Semantic Structure with article, section, and aside in HTML Jul 05, 2025 am 02:03 AM

The rational use of semantic tags in HTML can improve page structure clarity, accessibility and SEO effects. 1. Used for independent content blocks, such as blog posts or comments, it must be self-contained; 2. Used for classification related content, usually including titles, and is suitable for different modules of the page; 3. Used for auxiliary information related to the main content but not core, such as sidebar recommendations or author profiles. In actual development, labels should be combined and other, avoid excessive nesting, keep the structure simple, and verify the rationality of the structure through developer tools.

VSCode debugger for Java setup guide VSCode debugger for Java setup guide Jul 01, 2025 am 12:22 AM

The key steps in configuring the Java debugging environment on VSCode include: 1. Install JDK and verify; 2. Install JavaExtensionPack and DebuggerforJava plug-in; 3. Create and configure the launch.json file, specify mainClass and projectName; 4. Set up the correct project structure to ensure the source code path and compilation output are correct; 5. Use debugging techniques such as Watch, F8/F10/F11 shortcut keys and methods to deal with common problems such as class not found or JVM attachment failure.

How do I set up VS Code for Java development? How do I set up VS Code for Java development? Jun 29, 2025 am 12:23 AM

To use VSCode for Java development, you need to install the necessary extensions, configure the JDK and set up the workspace. 1. Install JavaExtensionPack, including language support, debugging integration, build tools and code completion functions; optional JavaTestRunner or SpringBoot extension package. 2. Install at least JDK17 and verify through java-version and javac-version; set the JAVA_HOME environment variable, or switch multiple JDKs in the status bar at the bottom of VSCode. 3. After opening the project folder, make sure the project structure is correct and enable automatic saving, adjust the formatting rules, enable code checking, and configure the compilation task to optimize the opening.

Windows search bar not typing Windows search bar not typing Jul 02, 2025 am 10:55 AM

When the Windows search bar cannot enter text, common solutions are: 1. Restart the Explorer or computer, open the Task Manager to restart the "Windows Explorer" process, or restart the device directly; 2. Switch or uninstall the input method, try to use the English input method or Microsoft's own input method to eliminate third-party input method conflicts; 3. Run the system file check tool, execute the sfc/scannow command in the command prompt to repair the system files; 4. Reset or rebuild the search index, and rebuild it through the "Index Options" in the "Control Panel". Usually, we start with simple steps first, and most problems can be solved step by step.

Why use the `Serializable` interface? Why use the `Serializable` interface? Jun 26, 2025 am 01:02 AM

ImplementingtheSerializableinterfaceinJavaallowsaclasstobeconvertedintoabytestreamforstorageortransmission.Asamarkerinterfacewithnomethods,itsignalsthattheclassisreadyforserialization,enablingmechanismslikeObjectOutputStreamtoprocessit.Failingtoimple

Differences Between Callable and Runnable in Java Differences Between Callable and Runnable in Java Jul 04, 2025 am 02:50 AM

There are three main differences between Callable and Runnable in Java. First, the callable method can return the result, suitable for tasks that need to return values, such as Callable; while the run() method of Runnable has no return value, suitable for tasks that do not need to return, such as logging. Second, Callable allows to throw checked exceptions to facilitate error transmission; while Runnable must handle exceptions internally. Third, Runnable can be directly passed to Thread or ExecutorService, while Callable can only be submitted to ExecutorService and returns the Future object to

See all articles