Java – CDI constructor injection is not applicable to transient non serializable dependencies

2020-08-02 • Java

I like CDI's constructor injection, but now I've found a use case where constructor injection obviously doesn't work as expected

In my example, I have two classes Class "beana" has no well-defined scope and does not implement serializable Class "beanb" annotates with @ sessionscope and implements serializable

public class BeanA{
}

@SessionScoped
public class BeanB implements Serializable{
    @Inject
    private BeanA beanA;
}

When I try to inject an instance of beana into beanb of a bean, I get an serializabledependencyexception from weld because beana is not serializable This is expected behavior

When I mark the "beana" field with "transient", there is no problem with the injection:

@Inject
private transient BeanA beanA;

Now weld will not throw any exceptions

This is very good for me, but when I like to use constructor injection, my understanding problems arise It no longer works when I do the following:

@SessionScoped
public class BeanB implements Serializable{
    private transient BeanA beanA;

    @Inject
    public BeanB(BeanA beanA){
        this.beanA = beanA;
    }

    public BeanB(){}
}

Using this code, I get unserializabledependencyexception again I think constructor injection and field injection are more or less equal, but obviously they are not What's my fault?

Solution

This seems to be a mistake If you make beana serializable, does everything work well? Which version of weld do you still use?

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Java