Inject Dynamic Values for the property in Spring - spring

Question

I am very new to Spring and while going through the DI topic through various sources (Book & Internet) I have seen the following pattern of defining bean configuration:
For example we have a class "SampleApp"
public class SampleApp
{
private int intValue;
private float floatValue;
public SampleApp(int value)
{
intValue = value;
}
public void setIntValue(int value)
{
intValue = value;
}
public void setFloatValue(float floatValue)
{
this.floatValue = floatValue;
}
}
Corresponding bean configuration is as follows:
<bean class="somepackage.SampleApp" id="samplebeanapp">
<constructor-arg value="15" />
<property value="0.5" name="floatValue"></property>
</bean>
We have been hard-coding the value here to 15 & 0.5.
Here are my questions :
Is it possible to pass those values as run time parameter with scope as prototype?
If yes, how can we do it? and please elaborate with some example.

Answer 1

Spring configuration files are processed at startup, and Spring singleton beans are instantiated too in that moment. They are not processed again during the application lifecycle, in normal conditions.
You can use such type of property injection to pass configuration values, while you can use injection of object references to determine the structure of your application.
To avoid hardcoding the values inside the XML files, you can extract them in property files using a PropertyPlaceholderConfigurer.
The principle is to program to interfaces as much as possible, so you don't tie yourself to any specific implementation. However, for the case you're thinking, you'll just pass the values at runtime.
Example: BeanA needs the services of DaoBean, but the DaoBean won't be instantiated by BeanA. It will be passed to BeanA through dependency injection and BeanA will only talk to a DaoInterface.
At this point if BeanA want to save 15 and 0.5, will call the methods with the actual values (or more commonly variables).
daoInterface.saveInt(15);
daoInterface.saveFloat(0.5);
I don't use dependency injection to pass the values in this case. Dependency injection is a great tool, but doesn't meant that it has to be used everywhere.