In order to support users under JDK 1.2, I think there needs to be some sort of abstraction to the Proxy.newProxyInstance(...) method.
If JDK 1.2, call net.sf.cglib.Proxy.newProxyInstance(...) otherwise call java.lang.reflect.Proxy.newProxyInstance(...).
Any ideas how to achieve this elegantly?
Neeme
Berin Loritsch wrote:
I drew up a change to the package.html file that will explain how to
remove the need for the Component interface while at the same time
supporting legacy components. If we are all for it, all I have to
do is commit it. The content follows:
-----------------------------------------------------------------
<body>
<p>
<b>Deprecated:</b> use the interfaces in the
<code>org.apache.avalon.framework.service</code> package instead.
Interfaces and implementation of the component management services
supporting container based management of componet lookup and
decommissioning.
</p>
<h1>Migration from This Package</h1>
<p>
The Avalon team has determined that the best way to remove the need
for this package in projects that existed before the team deprecated
the package is to use a dynamic proxy. There are two ways of defining
a dynamic proxy: using JDK 1.3's dynamic proxy generation code, and
using BCEL to write a special purpose proxy.
</p>
<p>
All the Avalon containers now employ this technique so that you can
confidently remove all deprecation warnings from your code by removing
the <code>Component</code> interface.
</p>
<p>
The code snippet below describes how to use JDK 1.3 to create a dynamic
proxy at runtime. The method <code>getProxy</code> is where the proxy
is actually created. The class <code>ComponentInvocationHandler</code>
takes care of handling the method calls.
</p>
<pre>
/**
* Get the Component wrapped in the proxy. The role must be the service
* interface's fully qualified classname to work.
*/
public Component getProxy( String role, Object service ) throws Exception
{
Class serviceInterface = m_classLoader.loadClass( role );
return (Component)Proxy.newProxyInstance( m_classLoader,
new Class[]{Component.class, serviceInterface},
new ComponentInvocationHandler( service ) );
}
/**
* Internal class to handle the wrapping with Component
*/
private final static class ComponentInvocationHandler
implements InvocationHandler
{
private final Object m_delagate;
public ComponentInvocationHandler( final Object delegate )
{
if( null == delegate )
{
throw new NullPointerException( "delegate" );
}
m_delagate = delegate;
}
public Object invoke( final Object proxy,
final Method meth,
final Object[] args )
throws Throwable
{
try
{
return meth.invoke( m_delagate, args );
}
catch( final InvocationTargetException ite )
{
throw ite.getTargetException();
}
}
}
</pre>
</body>
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