Application cases of Korm framework in the Java library
The Korm framework is a lightweight Java persistence framework. It provides a simple and easy -to -use API that can quickly map the Java object into a relational database.The following is an application case of the Korm framework in the Java library, covering a complete programming code and related configuration.
Case background:
Assuming that we are developing a student management system, we need to persist the data of the student object into a relational database.We choose to use the Korm framework to simplify the development of the data access layer.
Step 1: Add dependencies
First of all, we need to add the Korm framework to the project's Build.gradle file:
groovy
dependencies {
implementation 'com.github.pengrad:korm:0.6.0'
// Other dependencies ...
}
Step 2: Create a database table
Next, we need to create a database table called "Students" to store data for student objects.You can use the following SQL statements to create tables in the database:
sql
CREATE TABLE students (
id INT PRIMARY KEY,
name VARCHAR(255),
age INT,
class_id INT
);
Step 3: Define the physical class
Then, we need to define a Java class called "Student". This class represents students and uses the annotation of the Korm framework to mappore the attribute to the database table field.
import com.github.pengrad.korm.Korm;
public class Student {
// omit other attributes
@Korm.Id
private int id;
private String name;
private int age;
private int classId;
// omit the constructive method, Getter and Setter method
}
Step 4: Configure the data source
In the configuration file of the application, we need to configure the database connection information so that the Korm framework can be connected to the relational database.The following is a typical configuration example:
properties
# Database connection configuration
db.url=jdbc:mysql://localhost:3306/mydatabase
db.username=root
db.password=123456
Step 5: Use the Korm framework for data access
Now, we can use the Korm framework in the code to perform CRUD operations.Here are some common operation examples:
import com.github.pengrad.korm.Korm;
public class Main {
public static void main(String[] args) {
// Initialize the Korm framework
Korm.initFromProperties("config.properties");
// Create a student object
Student Student = New Student (1, "Zhang San", 18, 1);
// Insert the student object into the database
Korm.insert(student);
// Check the student object through ID
Student retrievedStudent = Korm.findById(Student.class, 1);
System.out.println(retrievedStudent.getName());
// Update the attributes of the student object
retrievedStudent.setAge(19);
Korm.update(retrievedStudent);
// Delete the student object from the database
Korm.delete(retrievedStudent);
}
}
The above example demonstrates how to use the Korm framework to map the student objects into the database and perform insertion, query, update and delete operations.
In summary, the application cases of the Korm framework in the Java library include adding dependencies, creating database tables, defining entity classes, configuration data sources, and using the Korm framework for data access.Through simple annotations and API calls, we can quickly realize the persistent operation of relational databases.