Search the parents of clazz for a renderer. The
renderer closest in the hierarchy will be returned. If no
renderers could be found, then the default renderer is returned.
The search first looks for a renderer configured for
clazz. If a renderer could not be found, then the
search continues by looking at all the interfaces implemented by
clazz including the super-interfaces of each
interface. If a renderer cannot be found, then the search looks
for a renderer defined for the parent (superclass) of
clazz. If that fails, then all the interfaces
implemented by the parent of clazz are searched and
so on.
For example, if A0, A1, A2 are classes and X0, X1, X2, Y0, Y1
are interfaces where A2 extends A1 which in turn extends A0 and
similarly X2 extends X1 which extends X0 and Y1 extends Y0. Let
us also assume that A1 implements the Y0 interface and that A2
implements the X2 interface.
The table below shows the results returned by the
get(A2.class) method depending on the renderers
added to the map.
| Added renderers | Value returned by get(A2.class) |
|---|
A0Renderer
| A0Renderer
|
A0Renderer, A1Renderer
| A1Renderer
|
X0Renderer
| X0Renderer
|
A1Renderer, X0Renderer
| X0Renderer
|
This search algorithm is not the most natural, although it is
particularly easy to implement. Future log4j versions
may implement a more intuitive search
algorithm. However, the present algorithm should be acceptable in
the vast majority of circumstances.
//System.out.println("\nget: "+clazz);
ObjectRenderer r = null;
for(Class c = clazz; c != null; c = c.getSuperclass()) {
//System.out.println("Searching for class: "+c);
r = (ObjectRenderer) map.get(c);
if(r != null) {
return r;
}
r = searchInterfaces(c);
if(r != null)
return r;
}
return defaultRenderer;
