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Retroactive Interfaces

DZone's Guide to

Retroactive Interfaces

· Java Zone
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We wanted to add some AoP HttpClient, and had to use Java Proxy which can only proxy an interface. HttpClient 3.0 doesn't have interfaces. So here's how I got around that problem with a "retroactive interface":

  1. create an interface
    public interface IHttpClient {
      int executeMethod(HttpMethod method)
        throws IOException, HttpException;
    }
    
  2. extend HttpClient, and implement the interface:
    public class MyHttpClient
      extends HttpClient 
      implements IHttpClient {
    }
    
  3. Use MyHttpClient as the implementation of the proxy. (I can't show the implementation of the proxy, but you should have an idea about the "retroactive interface" at this point)

Any questions?

From http://www.jroller.com/Solomon/entry/retroactive_interfaces

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