Drools4：对Shopping示范的分析

Drools4：对Shopping示例的分析

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1. ?
2. 1. package?org.drools.examples ??
   2. ??
   3. #?定义Package中使用mvel，默认是使用java ??
   4. dialect?"mvel"??
   5. ??
   6. #?列出客户购买商品的情况 ??
   7. rule?"Purchase?notification"??
   8. ????salience?10??
   9. ??
   10. ????when ??
   11. ????????$c?:?Customer() ??
   12. ????????$p?:?Purchase(?customer?==?$c)?????? ??
   13. ????then ??
   14. ????????System.out.println(?"Customer?"?+?$c.name?+?"?just?purchased?"?+?$p.product.name?); ??
   15. end?? ??
   16. ??
   17. #?当给与客户折扣时显示相关信息 ??
   18. rule?"Discount?awarded?notification"??
   19. ????when ??
   20. ????????$c?:?Customer() ??
   21. ????????$d?:?Discount(?customer?==?$c?) ??
   22. ????then ??
   23. ????????System.out.println(?"Customer?"?+?$c.name?+?"?now?has?a?discount?of?"?+?$d.amount?); ??
   24. end ??
   25. ??
   26. #?当折扣取消时显示相关信息 ??
   27. rule?"Discount?removed?notification"??
   28. ????when ??
   29. ????????$c?:?Customer() ??
   30. ????????not?Discount(?customer?==?$c?) ??
   31. ????then ??
   32. ????????$c.setDiscount(?0?); ??
   33. ????????System.out.println(?"Customers?"?+?$c.name?+?"?now?has?a?discount?of?"?+?$c.discount?); ??
   34. end ??
   35. ??
   36. #?如果客户购买的商品超过100元给与折扣 ??
   37. rule?"Apply?10%?discount?if?total?purcahses?is?over?100"???????????? ??
   38. ????no-loop?true???? ??
   39. ????dialect?"java"??
   40. ????when ??
   41. ????????$c?:?Customer() ??
   42. ????????$i?:?Double(doubleValue??>?100)?from?accumulate?(?Purchase(?customer?==?$c,?$price?:?product.price?),? ??
   43. ????????????????????????????????????????????????????????????????????sum(?$price?)?) ??
   44. ????then ??
   45. ????????$c.setDiscount(?10?); ??
   46. ????????insertLogical(?new?Discount($c,?10)?);?? ??
   47. ????????System.out.println(?"Customer?"?+?$c.getName()?+?"?now?has?a?shopping?total?of?"?+?$i?); ??
   48. end ??
   1 楼 john_summer 2008-05-08   发现一个问题，我分析了很久也没有结果，麻烦各位大虾帮想想
   如果把两个Product的价格都改为160，在retract之后，居然也激活了"Discount removed notification"了这个规则，但是此时"Apply 10% discount if total purcahses is over 100"的条件依然是满足的呀，insertLogical进去的Discout对象不应该被删除的呀，很是奇怪，麻烦各位帮解答一下，谢谢了