Re: How to get instance of the given dependency using Container

[Gabriel Belingueres <be...@gmail.com>]

This is a two step process: You can define a String property to hold
the "name" of the required instance to inject, and then inject the
appropiate instance with the given name.

For example you can define a constant:

  <constant name="my.constant" value="non-default-instance" />

  <bean type="com.foo.MyCustomClass" name="non-default-instance"
    class="com.foo.MyCustomClassProvider" />



@Inject(value="my.constant")
public void setConstant(String value) {
  this.constant = constant;
}

public initialization() {
  provider = container.getInstance(MyCustomClass.class, constant);
}

HTH,
Gabriel


2012/9/30 Aum Strut <au...@gmail.com>:
> Hi All,
>
> I am working on a requirement where i need to get instance of given class
> at run time using Struts2 Container and here is my Code
>
> public class MyClass{
>
>   private Class<? extends MyCustomClass> provider;
>
>  public MyClass(@inject Container container){
>
>     provider=container.getInstance();  // this is where i got strucked
>
>  }
>
> }
>
> Since Provider can by anyone who extends MyCustomClass so i am not
> sure before hand which implementation will be provided at run time.I
> am not sure how to get instance in this case from container.
>
> for e.g At run time there can be Either ClassA or ClassB or may be
> ClassC which all extends MyCustomClass.
>
> How can i pass this information to the container to get the instance
> of the class passed at run time?
>
>
> Thanks in advance
>
> -a

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Re: How to get instance of the given dependency using Container

[Aum Strut <au...@gmail.com>]

Thanks Gabriel for the help, but i am a bit confused about it.

Can you please help me to understand why we are using those two entries
like
one is a constant and other is a bean class?

while my understanding was that all i need to define a constant and based
on that i can get the actual class (extending MyCustomClass) from the
container.

I am still not sure about the use of bean? and if i go with your opinion
say

public class MyClass{
   private Class<? extends MyCustomClass> provider;

   public initialization() {
     provider = container.getInstance(MyCustomClass.class, constant);}
 }

Won't above statement will give an error "Type mismatch: cannot convert
from MyCustomClass to Class<? extends MyCustomClass>" ?

Thanks
-U
On Mon, Oct 1, 2012 at 6:43 AM, Gabriel Belingueres
<be...@gmail.com>wrote:

> This is a two step process: You can define a String property to hold
> the "name" of the required instance to inject, and then inject the
> appropiate instance with the given name.
>
> For example you can define a constant:
>
>   <constant name="my.constant" value="non-default-instance" />
>
>   <bean type="com.foo.MyCustomClass" name="non-default-instance"
>     class="com.foo.MyCustomClassProvider" />
>
>
>
> @Inject(value="my.constant")
> public void setConstant(String value) {
>   this.constant = constant;
> }
>
> public initialization() {
>   provider = container.getInstance(MyCustomClass.class, constant);
> }
>
> HTH,
> Gabriel
>
>
> 2012/9/30 Aum Strut <au...@gmail.com>:
> > Hi All,
> >
> > I am working on a requirement where i need to get instance of given class
> > at run time using Struts2 Container and here is my Code
> >
> > public class MyClass{
> >
> >   private Class<? extends MyCustomClass> provider;
> >
> >  public MyClass(@inject Container container){
> >
> >     provider=container.getInstance();  // this is where i got strucked
> >
> >  }
> >
> > }
> >
> > Since Provider can by anyone who extends MyCustomClass so i am not
> > sure before hand which implementation will be provided at run time.I
> > am not sure how to get instance in this case from container.
> >
> > for e.g At run time there can be Either ClassA or ClassB or may be
> > ClassC which all extends MyCustomClass.
> >
> > How can i pass this information to the container to get the instance
> > of the class passed at run time?
> >
> >
> > Thanks in advance
> >
> > -a
>
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>