Introduction to ORM framework in Java language

With the trend of modern software development, most applications need to interact with the database. Traditionally, we need to explicitly write SQL statements in code to query or update the database. However, this approach has many disadvantages, such as being difficult to maintain and error-prone. In order to solve these problems, the ORM (Object Relational Mapping) framework emerged, which allows us to automatically perform interactions with the database while writing code.

There are many ORM frameworks in the Java language, which are widely used in different fields and application scenarios. In this article, we will introduce several of the most popular ORM frameworks used in Java.

1. Hibernate

Hibernate is one of the most popular ORM frameworks in the Java world. It is developed by JBoss and is an open source framework. Hibernate establishes an ORM mapping for Java objects, allowing Java developers to operate relational databases such as MySQL, Oracle, PostgreSQL and SQL Server through Java classes.

Hibernate supports multiple mapping strategies, including XML mapping, annotation mapping and API-based mapping. At the same time, it also provides a rich query language (HQL) and a quasi-standard SQL language (Criteria API).

2. MyBatis

MyBatis is a lightweight ORM framework that helps map Java objects to SQL statements. It provides an XML or annotation method to configure different mapping relationships and query statements.

The biggest benefit of MyBatis is its flexibility and customizability. Users can write SQL statements, customize parameter mapping and

result set mapping, etc., and support the generation of dynamic SQL statements and cache management functions.

3. Spring Data JPA

Spring Data JPA is built on the ORM framework JPA (Java Persistence API) and provides a simple and efficient way to access relational databases. This makes operating the database simpler and easier to maintain. Spring Data JPA was launched in 2011. It uses annotations or XML files to define entity mappings. Spring Data JPA automatically generates SQL statements based on entity classes.

In Spring Data JPA, a large number of data operations can be implemented through the JpaRepository interface. Spring Data JPA also

provides various officially supported NoSQL implementation libraries, such as MongoDB and Redis.

4. JOOQ

JOOQ is an excellent ORM framework. Its main feature is that it provides a method to generate type-safe SQL code without developers having to write it by hand. SQL statement. JOOQ is committed to maintaining compatibility with SQL standards, and its API design is very intuitive and easy to use.

JOOQ's code generator can generate Java classes and interfaces from existing database schemas, so people can use existing database schemas to define domain models. For Java developers, JOOQ allows the use of object-oriented (OOP) programming style in the domain model of the database.

5. EclipseLink

EclipseLink is a high-performance, open source ORM framework widely used in Java enterprise applications. EclipseLink provides extensive support for the JPA specification while also providing many other advanced features such as Extensible Query Language (EQL) and dynamic persistence. At the same time, EclipseLink supports multiple data sources and multiple databases, including Oracle, MySQL, PostgreSQL and SQL Server.

Summary

This article introduces some popular Java ORM frameworks, all of which provide different features and uses. Choosing the ORM framework that suits you depends on your needs, such as your application scenario, data structure, and technical level. The ORM framework allows us to operate the database more easily, making Java development more efficient and easier to maintain.

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