Spring @Autowire批注

Question

I have a question on Spring Autowire Annotation.The scenario is like this : Iam using @Autowire on class A and using it in 2 places -Class B and Class C like below:

public class B 
{

@Autowired
private A a;
......

Map<String, Map<String,String>> map1=a.getNameValues();
Map<String, Map<String, String>> map2 = a.get("key");
if (map2!=null)
 map1.putAll(map2);

and also in other class C as shown below:

public class C 
 {

@Autowired
private A a;
......

Map<String, Map<String,String>> map1=a.getNameValues();
Map<String, Map<String, String>> map2 = a.get("key");
if (map2!=null)
map1.putAll(map2);
 }

The program control flows from Class B to class C. So since the class A is autowired in both the places. so when the control comes first to class B ,map2 is retrieved and put in map1 . when the control comes to Class C , map1 already has map2 values. What are the possible ways to control this kind of scenarios? As i want both classes to work independently and use the Autowired class. Let me know your thoughts.

Answer 1

@Autowire will automagically inject a spring bean into the given property.

It sounds like your question is actually related to the scope of the bean being injected. So assuming your A class looks like this:

@Component
public class A {
    ....
}

Then what will happen is spring will create a single instance (aka a Singleton) of A (in the given application context) and inject this into both B and C

Question - Is this the problem you are trying to solve? When you say you want both classes to act independently you mean the fact that the A object in B and C are the exact same object?

To get spring to wire a new instance of A you can simply change the scope of A to be prototype.

@Component
@Scope(value = "prototype")
public class A {
    ....
}  

or in xml

<bean id="a" class="A" scope="prototype"/>