Design Patterns Java™ Workbook

Chapter 23. Strategy

Figure 23.1. The Customer class relies on other classes for its recommendations,

including two off-the-shelf recommendation engines.

The LikeMyStuff and Rel8 engines both accept a Customer object and suggest
something to advertise to the customer. Both engines are configured to work for fireworks,
although LikeMyStuff requires a database and Rel8 works entirely from an object model.
The code for getRecommended() in class Customer mirrors Oozinoz's advertising
policies:

public Firework getRecommended()
{
// see if we're promoting a particular firework
try
{
Properties p = new Properties();
p.load(
ClassLoader.getSystemResourceAsStream(
"config/strategy.dat"));
String promotedFireworkName =
p.getProperty("promote");

if (promotedFireworkName != null)
{
Firework f = Firework.lookup(
promotedFireworkName);
if (f != null)
{
return f;
}
}
}
catch (Exception e)
{
}