The Singleton pattern is one of the most widely used design patterns in software development. It is a creational design pattern that ensures that only one instance of a class is created and that the instance is accessible globally.
The Singleton pattern is often used in the development of web applications. For example, in a Spring Boot application, the Singleton pattern can be used to create a singleton bean. A singleton bean is a bean that is created only once and is accessible globally.
There are many benefits to using the Singleton pattern in software development. Some of the benefits include:
There are several ways to implement the Singleton pattern in Spring Boot. In this article, we will take a look at two of the most popular ways to implement the Singleton pattern in Spring Boot:
The @Scope("singleton") annotation can be used to create a singleton bean. The @Scope("singleton") annotation is a Spring annotation that is used to specify the scope of a bean. The @Scope("singleton") annotation can be used on a class or on a method.
When the @Scope("singleton") annotation is used on a class, it indicates that all the beans in the class will be created as singletons. When the @Scope("singleton") annotation is used on a method, it indicates that the bean that is returned by the method will be a singleton.
The @Scope("singleton") annotation can be used as follows:
@Service
@Scope("singleton")
public class MyService {
// ...
}
In the code example above, the MyService class is annotated with the @Service and @Scope("singleton") annotations. The @Service annotation is a Spring annotation that is used to specify that the MyService class is a service. The @Scope("singleton") annotation indicates that the MyService class is a singleton.
The @Service("singletonService") annotation can be used to create a singleton bean. The @Service("singletonService") annotation is a Spring annotation that is used to specify that the class is a service. The @Service("singletonService") annotation can be used as follows:
@Service("singletonService")
public class MyService {
// ...
}
In the code example above, the MyService class is annotated with the @Service("singletonService") annotation. The @Service("singletonService") annotation indicates that the MyService class is a service and that it is a singleton.
In this article, we have looked at two of the most popular ways to implement the Singleton pattern in Spring Boot: