Spring Bean Scopes Explained With Code Samples

The Spring Frameworkicon allows defining scopes for a Spring Bean. Spring Bean scopes define the lifetime of a Spring bean. In this article, we will take a look at bean scopes.

What is Spring Bean Scope?

A Spring Bean scope specifies the lifetime of a Spring bean. So it specifies when the bean will be created and how long it will exist in the system.

Edit

What are the different bean scopes?

Spring supports the following bean scopes:

 

Singleton

This is the default bean scope. As per this scope, only one instance of a bean is created. Each time the bean is requested, the same instance is returned.

Prototype

As per this scope, a new instance of a bean is created each time the bean is requested.

Request

This bean scope is valid only for a web application. As per this bean scope, a new instance of the bean is created for each HTTP request. The bean stays alive until the HTTP request completes.  If you use this bean scope for a standalone application, your code will result in an error

Session

This bean scope is also valid only for a web application. As per this bean scope, a new instance of the bean is created for each HTTP session. The bean stays alive as long as the session is alive.  If you use this bean scope for a standalone application, your code will result in an error

Global Session

This bean scope is only valid for a portlet application. As per this bean scope, a new instance of the bean is created for each HTTP global session. It is similar to session scope used in a servlet based application.

How to define bean scopes?

Spring supports a @Scope annotation. You can use it to specify a Spring bean scope. As mentioned earlier, the default scope is singleton. However, if you want to specify the prototype scope for a bean, you can do it as follows:

 

@Service@Scope("prototype")public class MessageService {  //code here}

So this code defines a MessageService bean with prototype scope.

Further Learning

Spring MasterClass
Spring Tutorial For Beginners
Step by Step Spring MVC Tutorial
Spring Framework in Easy Steps

Conclusion

So, this article demonstrates the various Spring bean scopes like singleton, prototype, request, session and globalsession. It also demonstrates how you can define a bean scope.

Comments

Post a Comment

Popular posts from this blog

How to use logging in SpringBoot with code samples

Image
In this article, we will learn how to use logging in SpringBoot. Introduction There are several Java logging frameworks like logback, log4j, and so on. Spring Boot supports out-of-the-box support for logback. Let us learn how to use logging in SpringBoot with logback. Step 1 – Create a New Maven Project Create a new Maven project. (Refer to  this  blog post). This will create a project in Eclipse as follows:   Step 2 – Add the Spring Boot Dependencies Add the spring-boot-starter-web dependency to the pom.xml . So, the pom.xml should look as follows: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.learnjava</groupId> <artifactId>learnjava-springboot-logging-example</artifactId> <version>0.0.1-SNAPSHOT&
Read more

Python While Loop with code samples

Much like a Java while loop, you can use a Python while loop to repeatedly execute a block of code as long as a condition is true. In this article, we will learn more about the Python while loop. Python While loop Syntax A while loop in Python has the following syntax: while <condition>: loop body The while keyword is followed by a condition. If the condition evaluates to true, the body of the loop is executed. Once the body of the loop is completed, the condition is checked again and this is repeated until the condition evaluates to false at which point the loop is exited. While loop Sample Code The following code demonstrates how you can use the while loop: num=10counter=1total=0while counter<=num: total += counter counter+=1print("sum of first 10 numbers is",total) This code adds the numbers from 1 to 10 and prints the sum. It uses a while loop to iterate from 1 to 10. The while loop checks the condition counter <= num and if so adds the current value of count
Read more

How to convert a List to a Set

In this blog post ,I will be showing you how you can convert a List to a Set. Consider the following code snippet: public class ListToSetDemo {public static void main(String[] args) {List<Integer> list = Arrays.asList(5,3,11,15,9);//Method 1Set<Integer> set = new HashSet<Integer>(list);System.out.println("Set is "+set);//method 2Set<Integer> set2 = new HashSet<Integer>();set2.addAll(list);System.out.println("Set is "+set2);}} This code demonstrates two ways to convert a List to a Set. Method 1 Here, we are creating a new HashSet . We are invoking the constructor that accepts a Collection object. Here, we are passing in the input list to this constructor.   Method 2 Here again, we are creating a new HashSet . However, we are using the default constructor. We are then invoking the addAll method and passing in the input list.   When you run this code, it will print the following output: Set is [3, 5, 9, 11, 15]Set is [3, 5, 9, 11, 15] No
Read more