Design pattern Start--policy mode

Policy mode

Role:

A policy pattern is a method that defines a series of algorithms, all of which are done the same work, but are implemented differently, and he can invoke all the algorithms in the same way. The strategy model is easy to understand, and even if you have not studied design patterns, you can think of this pattern to solve problems in real-world problems.

Compared to the factory model:

• The function of the factory pattern is to instantiate the object , which does not contain the action of the object
• In the policy mode, it is encapsulated again, not only to instantiate the algorithm in its own class, but also to manipulate the algorithm. the client has been encapsulated again, making the client's code simpler and clearer.

Class Diagram:

Realize:

1. Form of Cashsuper algorithm

 Public Abstract class Cashsuper {    publicabstractdouble GetCash (double  );}

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2, three inherited algorithms

 Public classCashrebateextendsCashsuper {Private Doublerebate = 1;  PublicCashrebate (Doublerebate) {         This. Rebate =Rebate; } @Override Public DoubleGetCash (DoubleMoney ) {        //TODO auto-generated Method Stub        returnMoney *Rebate; }} Public classCashreturnextendsCashsuper {Private DoubleCondition = 0; Private DoubleMoneyreturn = 0;  PublicCashreturn (DoubleConditionDoubleMoneyreturn) {         This. Condition =condition;  This. Moneyreturn =Moneyreturn; } @Override Public DoubleGetCash (DoubleMoney ) {        if(Money >= This. Condition) { Money-= Math.floor (money/condition) *Moneyreturn; }        returnMoney ; }} Public classNormalcashextendsCashsuper {@Override Public DoubleGetCash (DoubleMoney ) {        //TODO auto-generated Method Stub        returnMoney ; }}

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3. Context class for instantiating algorithms and invoking algorithm operations

 Public classCashcontext {Cashsuper cs=NULL;  Publiccashcontext (String type) {Switch(type) { Case"Normal": CS=NewNormalcash ();  Break;  Case"Rebate": CS=NewCashrebate (0.8);  Break;  Case"Return": CS=NewCashreturn (300,80);  Break; }    }     Public DoubleGetResult (DoubleMoney ) {        returnCs.getcash (Money); }}

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4, the client class, for testing

 Public class Client {    publicstaticvoid  main (string[] args) {        = "return"  ;         double money =N;         New cashcontext (type);        System.out.println (Cc.getresult (Money));}    }

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Design pattern Start--policy mode