Re: [Springframework-developer] Issue SPR-285 - proxying with no-arg constructor in CGLIB

[Rob H. <ro...@ca...>]

Colin,

The constructor on the target bean will be fired when the proxy is 
created with the arguments supplied in the <constructor-arg> tags. When 
the proxy is created the constructor is called again, and currently will 
in certain circumstances override any state set by the first call of the 
constructor. This is behavior is covered under another issue and teh 
CGLIB guys are looking at a fix to allow us to avoid redirecting calls 
during proxy creation so that no state gets overwritten.

The best way forward as I see it is to add 
setConstructorArguments(Object[]) and 
setConstructorArgumentTypes(Class[]) to ProxyFactoryBean. The user can 
specify both if he chooses otherwise he just needs to specify a value 
for the first and the Spring will attempt to determine the types (very 
loosely, using the types of the Objects passed in ).

Rob

Colin Sampaleanu wrote:

> The main issue I see, unless I'm missing something, with passing in 
> constructor args to the ProxyFactoryBean is having decent type 
> conversion. When you pass in properties or normal constructor-args to 
> a bean, you get decent PropertyEditor based type conversion happening. 
> The code would need to do something similar to 
> ArgumentConvertingMethodInvoker and its superclass MethodIInvoker. Now 
> the latter are kind of stupid in that they get confused when there are 
> multiple matching methods. If the ProxyFactoryBean variant passed 
> along as the second param a Class[], then there's no ambiguity. It's 
> also more of a pain to use, and maybe should be possible to pass in a 
> null array, in which case the code will do its best, which might be 
> enough when there're only one or two non-ambiguous constructors.
>
> But what happens with the constructors from the target bean? They just 
> get ignored?
>
>
> Rob Harrop wrote:
>
>> All,
>>
>> We really need to come to a desicion of how this should be 
>> implemented if I am to get a fix done in time for 1.1.3. Currently I 
>> see two ways to solve the problem:
>>
>> 1. Add setConstructorArgs(Object[], Class[]) to ProxyFactoryBean
>> 2. Attempt to locate the <constructor-arg> definitions of the target 
>> bean, although I think this involves iterating over the bean 
>> definitions attempting to match to the target. Also when using 
>> anything but a SingletonTargetSource the match might not succeed.
>>
>> I am taking a break this week but I will be around for discussion on 
>> this - just won't be starting it until Monday.
>>
>> Rob
>
>
>
>
>
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