I saw 'application' scope in the following blog. Is it true?
http://www.concretepage.com/spring/spring-bean-scope-example-using-scope-annotation-and-xml-for-singleton-prototype-request-session-global-session-and-application-scope-with-scoped-proxy
Because, as per my surfing, I got to know spring has only the below 5 scopes. Please correct me if I'm wrong.
Singleton
Prototype
Request
Session
Global Session
There is a section on the official doc which is related to the bean scopes:
7.5 Bean scopes
Basically, they define the next:
singleton (Default) Scopes a single bean definition to a single object instance per Spring IoC container.
prototype
Scopes a single bean definition to any number of object instances.
request
Scopes a single bean definition to the lifecycle of a single HTTP request; that is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext.
session
Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext.
globalSession
Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a Portlet context. Only valid in the context of a web-aware Spring ApplicationContext.
application
Scopes a single bean definition to the lifecycle of a ServletContext. Only valid in the context of a web-aware Spring ApplicationContext.
websocket
Scopes a single bean definition to the lifecycle of a WebSocket. Only valid in the context of a web-aware Spring ApplicationContext.
Furthermore, as Spring 3.0 exists other scope thread scope but is not registered by default, moreover you could even create your own scope:
As of Spring 3.0, a thread scope is available, but is not registered
by default. For more information, see the documentation for
SimpleThreadScope. For instructions on how to register this or any
another custom scope, see the section called “Using a custom scope”.
There is a section which explains how to define your custom scope:
7.5.5 Custom scopes
Respect to Application scope, they define it as next:
The Spring container creates a new instance of the AppPreferences bean
by using the appPreferences bean definition once for the entire web
application. That is, the appPreferences bean is scoped at the
ServletContext level, stored as a regular ServletContext attribute.
It also explains the difference between a Spring singleton bean:
This is somewhat similar to a Spring singleton bean but differs in two
important ways: It is a singleton per ServletContext, not per Spring
'ApplicationContext' (for which there may be several in any given web
application), and it is actually exposed and therefore visible as a
ServletContext attribute
So in case you are looking to use with XML:
<bean id="apps" class="com.App" scope="application"/>
Or annotation:
#ApplicationScope
#Component
public class App {
// ...
}
application
Scopes a single bean definition to the lifecycle of a ServletContext. Only valid in the context of a web-aware Spring ApplicationContext.
Follow the link for more details:
http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#beans-factory-scopes
Related
I am working on a spring boot api where I have used a query string and doing some replace operations on it on every get request but even after I trigger a new request the string is in the same state as that of previous GET call and the query gets messed up.
Here's my code:
private static String GET_SETS = "Select * from table #check#";
Now I have 1 method in the same repository which gets called on a get request:
public PagedList getSets(Map params) {
if (!StringCheck.isEmpty(flattenMap.get("entity_name"))) {
GET_SETS = GET_CODE_SETS.replace("#check#", " WHERE e.#entity_name# = ?");
values.add((String)flattenMap.get("entity_name"));
} else {
GET_SETS = GET_SETS.replace("#check# #status_check#", "");
}
}
Now whenever a GET request is triggered,some changes are done to GET_SETS string according to map values,and again in the next requests the same changes are there.
How to solve this? I want the query string to be whats defined at the start on every request. Thanks
Your problem is most likely caused by using the default scope, which is singleton, when creating your Spring components.
Spring provides the following scopes for creating beans
(source):
singleton (default): Scopes a single bean definition to a single object instance for each Spring IoC container
prototype: Scopes a single bean definition to any number of object instances.
request: Scopes a single bean definition to the lifecycle of a single HTTP request. That is, each HTTP request has its own instance
of a bean created off the back of a single bean definition. Only valid
in the context of a web-aware Spring ApplicationContext.
session: Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring
ApplicationContext.
application: Scopes a single bean definition to the lifecycle of a ServletContext. Only valid in the context of a web-aware Spring
ApplicationContext.
websocket: Scopes a single bean definition to the lifecycle of a WebSocket. Only valid in the context of a web-aware Spring
ApplicationContext.
If we don't specify any scope explicitly, the default singleton scope is used. This means that the service/component is shared between multiple injections, hence it is reused for multiple GET requests.
In order to get rid of this behavior, we might use something like request scope, although in this case we have to take care of thread-safety as well.
Other solution is to not use member variables and try to use local variables for things such as GET_SETS.
I have a callable type class. It is a annotated with #component. I would like to create multiple instances of the callable class. To do so, I am using the application context. The problem is it simply does not work.
Refer Bean scope you want to use:
https://docs.spring.io/spring-framework/docs/3.0.0.M3/reference/html/ch04s04.html#:~:text=2%20The%20prototype%20scope,method%20call%20on%20the%20container).
singleton - once for each IoC container, your application context
prototype- multiple beans for multiple object instance
request - in case of web aware app context, each bean to a particular HTTP request, and new instance for another
session- for each HTTP session.
global session - as what name says.
depending on your use select scope as well explained by #BeUndead.
Does spring always create a new IOC container for each new client if not then how does it manage the singleton beans? I'm really confused that how does one singleton bean managed requests from different users?
No. It will not create new IOC container for each new client. That's why bean scope is there. If you want to keep bean per request you can use request as bean scope. Singleton is not thread safe. So each new request, it will share the instance properties.
Request scope definition from documentation
Scopes a single bean definition to the lifecycle of a single HTTP
request; that is each and every HTTP request will have its own
instance of a bean created off the back of a single bean definition.
Only valid in the context of a web-aware Spring ApplicationContext.
In an imported spring context XML file I define a bean instance that implements BeanPostProcessor.
In the importing spring context I define a number of beans (using BeanDefinitionBuilder in a custom BeanDefinitionParser).
Not all defined beans are given to the postProcessBeforeInitialization() method on my BeanPostProcessor.
It seems that some other FactoryBeans somehow affect this situation. When looking in the ApplicationContext instance with a debugger I can see all my beans inside - also the ones not being given to the BeanPostProcessor.
How can this happen?
Do we have concept of page scope in spring3?
Suppose user open multiple tab then if data is stored in session then in some situation things may go wrong. Imagine user will open two tab in the browser. And in both these tab he is working on same page so that he can complete his work faster. So if some data is referred from session then in that case application can reach to an error state.
So to avoid this I want to store data in page scope,so that each page data will not be mixed in session? is it directly available in spring or I need to write my own conversation logic and page scope?
In Spring you have following scope :
singleton - (Default) Scopes a single bean definition to a single object instance per Spring IoC container.
prototype - Scopes a single bean definition to any number of object instances.
request - Scopes a single bean definition to the lifecycle of a single HTTP request; that is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext.
session - Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext.
global session - Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a portlet context. Only valid in the context of a web-aware Spring ApplicationContext.
Do we have concept of page scope in spring3?
--> In Spring you don't have page scope but you can configure your particular bean to use request scope.
Reference : Spring Documentation