This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
DispatchAction and LookupDispatchAction both are used to combine related operations into a single class, so that they can share common resources like helper methods without exposing them to other classes.
DispatchAction selects the method to execute depending on the request parameter value which is configured in the xml file. This will be problematic for internationalized applications since the values will be different for different locales. So, LookupDispatchAction looks into the resource bundle file and find out the corresponding key name. We can map this key name to a method name by overriding the getKeyMethodMap() method.