package org.monjo.document;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.CallbackFilter;
import net.sf.cglib.proxy.Dispatcher;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
public class DirtWatcherProxifier {
private static final Set<Method> OBJECT_METHODS = new HashSet<Method>(Arrays.asList(Object.class.getDeclaredMethods()));
private static final Set<Method> INTERNAL_METHODS = new HashSet<Method>(Arrays.asList(DirtFieldsWatcher.class.getDeclaredMethods()));
private static final CallbackFilter IGNORE_BRIDGE_AND_OBJECT_METHODS = new CallbackFilter() {
public int accept(Method method) {
if (method.isBridge() || OBJECT_METHODS.contains(method)) return 1;
if (INTERNAL_METHODS.contains(method)) return 2;
String name = method.getName();
return name.startsWith("set") || name.startsWith("add") ? 0 : 1;
}
};
public static <T> T proxify(final T pojo) {
if (pojo instanceof DirtFieldsWatcher) {
return pojo;
}
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(pojo.getClass());
enhancer.setInterfaces(new Class[] { DirtFieldsWatcher.class });
enhancer.setCallbackTypes(new Class[] { MethodInterceptor.class, Dispatcher.class, MethodInterceptor.class });
enhancer.setCallbackFilter(IGNORE_BRIDGE_AND_OBJECT_METHODS);
BaseObject baseObject = new BaseObject();
enhancer.setCallbacks(new Callback[] { new WatchSetterInterceptor(pojo, baseObject), new Dispatcher() { public Object loadObject() throws Exception {return pojo;} }, new BypassBaseObjectInterceptor(baseObject) });
return (T) enhancer.create();
}
private static class WatchSetterInterceptor implements MethodInterceptor {
private BaseObject baseObject;
private Object target;
public WatchSetterInterceptor(Object pojo, BaseObject baseObject) {
this.target = pojo;
this.baseObject = baseObject;
}
@Override
public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
baseObject.addDirtField(method.getName());
return method.invoke(target, args);
}
}
private static class BypassBaseObjectInterceptor implements MethodInterceptor {
private BaseObject baseObject;
public BypassBaseObjectInterceptor(BaseObject baseObject) {
this.baseObject = baseObject;
}
@Override
public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
return method.invoke(baseObject, args);
}
}
private static class BaseObject implements DirtFieldsWatcher {
private Set<String> dirtFields = new HashSet<String>();
public Set<String> dirtFields() {
return dirtFields;
}
public void addDirtField(String fieldName) {
dirtFields.add(fieldName);
}
}
}