singleton « Core « Spring Q&A





1. spring wiring, singleton versus prototype    stackoverflow.com

just reading up on spring, and when using DI in spring, if you set the bean to be a singleton (default), then a single instance of the class will be 'dispensed', ...

2. Spring singleton lifecycle    stackoverflow.com

Reading this

When a bean is a singleton, only one shared instance of the bean will be managed and all requests for beans with an ...

3. Dependency Injection into your Singleton    stackoverflow.com

I have a singleton that has a spring injected Dao (simplified below):

public class MyService<T> implements Service<T> {
    private final Map<String, T> objects;
    private static MyService ...

4. How does Singleton work in Spring?    stackoverflow.com

Spring default setting is Singleton for beans. So does that mean when 100 users access the same the site (service or bean), do those 100 sessions share the single instance of ...

5. Singleton and @Autowired returning NULL    stackoverflow.com

I have a repository manager that manages my repositories. I have the @Autowired to instantiate my properties, but they are always null. The beans are correctly configured in my ...

6. Spring and @Autowired - when does the autowiring take place?    stackoverflow.com

I have a class that works like so:

@Component
public class MyClass
{

  @Autowired
  public void setDataSource(DataSource dataSource)
  {
    ...
  }

  public void doSomethingUsingDataSource()
  {
 ...

7. Spring singleton created multiple times    stackoverflow.com

I have a bean defined in my spring web application and I am expecting to have only one instance of this bean, here is my bean definition:

<bean id="accessControl" class="my.spring.app.AccessControl" />
In the ...

8. Preventing non-Singleton use outside of Spring    forum.springsource.org

Hi, I have a DAO which I proxy and set up with an Interceptor using Spring. However, there are no guarantees that Spring will be used everywhere the class is used. ...

9. Why aren't my singletons instanciated?    forum.springsource.org

Why aren't my singletons instanciated? Springers, It was my understanding that the BeanFactory instanciates the beans defined in the config file, providing lazy-init is set to false and the bean is ...





10. Singleton vs. Prototype    forum.springsource.org

Singleton vs. Prototype I've now successfully deployed two applications based on the Spring Framework. I am constantly amazed at this software and the significant improvements I've made in application creation. Now ...

11. issues with Singleton    forum.springsource.org

HTML Code: public class MessageHandler { private static ResourceBundleMessageSource messageResources; public static String getMessage(final String errorCode) { return getMessage(errorCode, null); } public static String getMessage(final String errorCode, final Object[] params) { ...

12. Best approach to create prototype within Singleton    forum.springsource.org

I have a facade (which is a singleton) but my business layer object is not (i.e. is a prototype). E.g my facade delegates the logic to the business layer (my bl ...

13. Neither singleton nor prototype    forum.springsource.org

Neither singleton nor prototype Hi, I'm designing a web application with its own set of view classes using Spring and WebWork/Xwork. I use the existing Spring-WebWork integration project to get action ...

14. Singletons by default    forum.springsource.org

Singletons by default I am wondering why the BeanFactory ( org.springframework.beans.factory.BeanFactory in 3.0.5 ) returns singleton instances by default and that I have to specify I want a new instance every ...

15. Singleton? Or not    forum.springsource.org

Singleton? Or not I am new to spring, and I am apologize if my question is stupid. I started to use spring frame work at current project but was not sure ...

16. Multiple Singletons ?    forum.springsource.org

Hello, I have a singleton with some post setup code that needs to be called so I am using: init-method="initialise" But somehow in my application this is getting called twice ??! ...





17. Is singleton->instantiable an error?    forum.springsource.org

Is singleton->instantiable an error? I can't see why a singleton with a dependency on a non-singleton (which I prefer to call instantiable rather than prototype) is not an error. Is there ...

18. not so Singletons, and Cyclic references    forum.springsource.org

not so Singletons, and Cyclic references I am having problems keeping my Singletons as singletons. I have a cyclic reference between two beans (references are runtime - through interfaces, not concrete) ...

19. What does Singleton really mean?    forum.springsource.org

What does Singleton really mean? Hello All, My understanding until now has been that Spring always created Singleton bean instances unless singleton="false" was specified. But here is what I did.

20. Why is everything singleton ?    forum.springsource.org

Hi, I am new to Spring framework. I saw some of the examples that come with spring's download. In Spring manual, it says, if you dont specify what kind of object ...

21. singleton, unique, ... subtree-visible?    forum.springsource.org

singleton, unique, ... subtree-visible? Hello. I've got a problem. I have a structure of beans like this: Code: topBean subBean1 handler1 handler2 ... handlerN subBean2 handler1 ... handlerM subBean3 handler1 ... ...

22. non-singleton EntityInterceptors    forum.springsource.org

non-singleton EntityInterceptors I've seen lots of example code implementing auditing using a Hibernate entity interceptor. But I don't understand why these solutions don't suffer from concurrency problems. My understanding is that ...

23. default is singleton?    forum.springsource.org

I am developing the web and using the WebApplicationContext. 1) The singleton is base on the session right? 2) if this happen then it will have many sessionfactory and dataSource then. ...

24. singleton, abstract/parent attributes    forum.springsource.org

I don't think I've seen this documented anywhere: Is the "singleton" attribute inherited by child bean defs? I see this in the reference guide: "The remaining settings will always be taken ...

25. To Singleton or Prototype    forum.springsource.org

Hi All, I am currently developing a Web based reporting application based on spring Core and Web MVC framework. The highlevel architecture is part of the attached document which has flow ...

26. Singleton and SPRING    forum.springsource.org

Singleton and SPRING Hi, I have a POJO java class which I would like it to be singleton throughout the whole application server (cross all modules). Is it possible? Specifically, I ...

27. Eager destruction of singletons    forum.springsource.org

When spring's DefaultListableBeanFactory fails to pre-instantiate all of it's singleton beans, it immediately destroys all of them to ensure that they aren't hanging around in a bad state. This makes sense, ...

28. question: how can I destroy singletons    forum.springsource.org

question: how can I destroy singletons Question: how can I destroy the singletons in the bean cache? I have some beans that need to be singletons: JMS session and JMS connection ...

29. Definition of Spring "singleton"?    forum.springsource.org

Definition of Spring "singleton"? Hi, everyone. I've looked through the documentation at Spring and in my books (Spring in Action and Pro Spring), but I can't find a clear definition for ...

30. singleton - To be or not to be ?    forum.springsource.org

I am new to Spring. I have gone through reference materials and sample applications and it says default behavior for bean is singleton. In real world java applications I have seen ...

31. Dependancy Injection and Singletons    forum.springsource.org

Dependancy Injection and Singletons Hi I've just recently started taking a look at the Spring Rich Client and I've run into a bit of a conundrum. I thought that the aim ...

32. Parameterized Singleton problem    forum.springsource.org

Hi, We have a lot of Object Managers in our existing code which manage objects based on parameters to a static factory method. For eg. Code: Object obj1 = ObjectManager.getInstance("param1"); Code: ...

33. Interesting Singleton Interaction    forum.springsource.org

Jul 31st, 2006, 06:58 PM #1 RShelley View Profile View Forum Posts Private Message Senior Member Join Date Jul 2006 Posts 136 Interesting Singleton Interaction My application uses Spring to wire ...

34. singleton destroy method gets called twice    forum.springsource.org

singleton destroy method gets called twice I start my app context and then destroy. The destroy method gets called twice on my singleton and so in my real application it tries ...

35. statis block solve singleton issue.    forum.springsource.org

Can the static block bellow solve the singleton issue? static { appContext = FacesContextUtils.getWebApplicationContext( FacesContext.getCurrentInstance()); } private App(){ } public static Object lookupBean(String beanName) { return appContext.getBean(beanName); }

36. what is singleton in Spring?    forum.springsource.org

Hi , can somebody explained what is the purpose/benefit of singleton in Spring in real worl analogy ? I know a lot people saying that singleton means per application context. If ...

37. When is a singleton not a singleton?    forum.springsource.org

When is a singleton not a singleton? I have a singleton DAO with some state that is constructed in a spring XML file as a singleton. It is then passed into ...

38. How to keep state for singletons?    forum.springsource.org

How to keep state for singletons? In my application i have a screen with a list of items and some entry fields to limit the list to only those items that ...

39. Class variables and singleton="yes"    forum.springsource.org

Class variables and singleton="yes" In my application i have a screen with some entry fields. The backing object of the form controller has variables to save the search criteria fields. (much ...

40. Two instances of a singleton created for timer tasks    forum.springsource.org

Two instances of a singleton created for timer tasks We are using ScheduleTimerTasks in our application. We understood the classes that are called by the timer tasks would only be instantiated ...

41. a protoype inside a singleton?    forum.springsource.org

a protoype inside a singleton? hi.. i have class called command, which accepts in it setter CommandType class this CommandType class accepts in it's constuctor a Resource class all of this ...

42. setting static variables to hold singletons    forum.springsource.org

setting static variables to hold singletons I have created a class which encapsulates system properties called SystemProps. I want to use this class as a singleton, since there should really only ...

43. two-pass singleton instantiation    forum.springsource.org

two-pass singleton instantiation I need to be able to create beans in two passes using a bean factory. The first pass creates the objects, the second pass links all the beans ...

44. Singleton referencing Prototype    forum.springsource.org

Singleton referencing Prototype Hi all, I believe this is a simple question but I have not been able to find an answer via the forum, Google, and digging around the documentation. ...

45. Point cut not getting called on singleton class    forum.springsource.org

Hi, We have a serviceInvoker bean which is a singleton class with private constructor and static method which returns the instance. Code: public class ServiceInvoker implements ApplicationContextAware { private static ServiceInvoker ...

46. Persisting singletons with state    forum.springsource.org

Persisting singletons with state I'm looking for an architecture best practice for persisting singletons with state. I'm sure this comes up often enough, and maybe I'm just too tired to see ...

47. singleton    forum.springsource.org

Suppose i declare a bean in my conf. file as singleton="false" And in another bean i pass this bean as dependency through setter.. Then for this bean ...wont the earlier bean ...

48. Moving Spring 2.0.4 attribute singleton problem    forum.springsource.org

Moving Spring 2.0.4 attribute singleton problem I'm upgrading to Spring 2.0.4, i have changed the jars. I have define beans in applicationContext-services.xml file like this

49. Four instances of EVERY singleton being created!!! Help!    forum.springsource.org

Four instances of EVERY singleton being created!!! Help! I'm using spring with tomcat, and the app seems to work fine, but now I'm going some caching stuff, and I'm running into ...

50. Eager singleton init not so eager?    forum.springsource.org

Eager singleton init not so eager? I'm sure I'm missing something painfully obvious here but so far I haven't stumbled upon it. I've written a very simple bean that configures another ...

51. Dependency Injection and Singleton    forum.springsource.org

Dependency Injection and Singleton Hi My undertstanding of singleton is "We should not use singleton class If singleton class methods are depend on instance variable because If they depend we need ...

52. To singleton or not ?    forum.springsource.org

Hi. My application has DAOs, Services, Facades and WebWork actions. WebWork actions shouldn't be singletons, but what about the other domain objects ? Thanks.

53. question on singleton?    forum.springsource.org

Hi, I am not sure whether someone has asked this already. I am a newbie and need one info. the spring doc says "Springs concept of singleton bean is quite different ...

54. Dependency Injection, Singleton and nonSsingleton ?    forum.springsource.org

Dependency Injection, Singleton and nonSsingleton ? Hello, Working with an application that is implemented in 2 different ways; using applicationContext-j2EE.xml + applicationContext-App1-j2ee.xml + applicationContext-App2-j2ee.xml. Using applicationContext-j2EE.xml as the 'parent' for the ...

55. Singleton class: unexpected field value    forum.springsource.org

Singleton class: unexpected field value I may be overlooking something fundamental here. I'm new to servlets/beans/Spring. I have an application context configuration file: Code: ...

56. Singleton/Nonsigleton Issues    forum.springsource.org

Singleton/Nonsigleton Issues I am a newbie to Spring. I was trying to implement an example of Non-Singleton Bean. The java code is as follows: import org.testng.Assert; import org.testng.annotations.DataProvider; import org.testng.annotations.Test; import ...

57. Singletons might not be singletons!    forum.springsource.org

Hello I just read this: http://kaksles.org/2005/09/12/spring...be-singletons/ which describes a problem where bean initialization happens twice. What the article doesn't explain is why this happens - the reason for my post. I ...

58. Deferring the instantiation of singletons    forum.springsource.org

Env: JDK1.6, Spring 2.5 In my application context, singletons are (by default) instantiated by the context load listener. I would like to defer the instantiation of some of the beans to ...

59. Singletons or prototypes    forum.springsource.org

I have asked similar question before and here is what I understood, wish it can help: Normally, tasklet is singleton by default. Therefore, if the tasklet's logic is stateless, it will ...

60. Multiple Singletons?!    forum.springsource.org

Multiple Singletons?! In my Spring XML configuration I define a number of beans and as per the default they are singletons. Then, I define other beans which are injected with these ...

61. Prototype injected into Singleton problem    forum.springsource.org

Prototype injected into Singleton problem I'm trying to inject a prototype-scoped bean into a singleton-scoped bean. I think this is what I need, because I basically want the prototype bean to ...

62. Singleton by Class Name?    forum.springsource.org

63. Dynamically replace and re-wire singletons ?    forum.springsource.org

Dynamically replace and re-wire singletons ? Hi, I tried google'ing for this but to no avail , please forgive me if this has been answered before. Let's assume a very basic ...

64. Singleton instantiated twice?    forum.springsource.org

Hi, I'm having a problem with a singleton bean that is instantiated twice (I can see this from printing to System.out in the constructor). I cannot figure out why. Code:

65. One very basic question regarding singleton    forum.springsource.org

One very basic question regarding singleton Hi, I am trying to learn Spring now, and read somewhere saying singleton design pattern is very good scalable architecture design solution (It requires stateless ...

66. Can't use the singleton attribute    forum.springsource.org

Can't use the singleton attribute I'm using the xmlns and xsi:schemaLocation attributes in my beans tag for my applicationContext.xml file instead of using the dtd for defining DOCTYPE. The problem I'm ...

67. Singleton safety ?    forum.springsource.org

In a web application, if we define bean (like service, DAO) as singleton, then Spring will manage thread safety ? it will down the performance ? what about the database connection ...

68. Multiple instances of singleton are constructed    forum.springsource.org

Multiple instances of singleton are constructed I'm going to delve into this further myself, but maybe someone already knows the answer. I have a J2EE app consisting of an EAR file ...

69. Global application level is singleton and i want to create a custom class "Prototype"    forum.springsource.org

Global application level is singleton and i want to create a custom class "Prototype" Hi All, In my current project, the Global scope of my entire applictaion is Singleton. For one ...

70. Running many legacy java application instances that contains singletons    forum.springsource.org

Running many legacy java application instances that contains singletons Hi, The whole objective is to run the same java application many times in the same JVM : I would like to ...

71. Singleton and Spring    forums.oracle.com