design pattern cqrs java sample?
The Command Query Responsibility Segregation (CQRS) pattern is a design pattern that separates the read and write operations of an application into separate models. In CQRS, commands are used to modify the state of the system, while queries are used to retrieve data from the system.
Here is a simple Java sample implementation of the CQRS pattern:
1. Define the Command and Query models:
```java
public class CreateOrderCommand {
private String orderId;
private String customerName;
// other order details, setters and getters
}
public class GetOrderQuery {
private String orderId;
// getters and setters
}
```
2. Implement the Command Handler:
```java
public class OrderCommandHandler {
public void handle(CreateOrderCommand command) {
// create order logic
}
}
```
3. Implement the Query Handler:
```java
public class OrderQueryHandler {
public Order getOrder(GetOrderQuery query) {
// retrieve order logic
return order;
}
}
```
4. Create a Controller or Service to handle incoming requests:
```java
public class OrderController {
private OrderCommandHandler commandHandler;
private OrderQueryHandler queryHandler;
public void createOrder(CreateOrderCommand command) {
commandHandler.handle(command);
}
public Order getOrder(GetOrderQuery query) {
return queryHandler.getOrder(query);
}
}
```
Note that this is just a basic example to demonstrate the concept of CQRS in Java. In a real-world application, you would typically have more complex business logic and infrastructure components involved.
Remember to adapt this sample code to fit your specific requirements and architecture.
