Java设计模式之--策略模式(strategy)

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行为型模式:

 行为型模式,共11种:策略模式、模板方法模式、观察者模式、迭代子模式、责任链模式、命令模式、备忘录模式、状态模式、访问者模式、中介者模式、解释器模式。根据它们的具体技术实现可分为4类,第一类:通过父类与子类的关系进行实现。第二类:两个类之间。第三类:类的状态。第四类:通过中间类如下图:



策略模式(strategy)

概念:

义一系列的算法,把每一个算法单独实现并封装, 并且使它们可相互替换。使得算法可独立于使用它的客户而变化。客户可以决定采用哪种策略(算法)

案例:

Message 选择通过Email 还是短讯发送信息给特定联系人

来看类图:


联系人 类

public class PhoneContract {    private String email;    private String phone;    private String name;    public String getEmail() {        return email;    }    public PhoneContract setEmail(String email) {        this.email = email;        return this;    }    public String getName() {        return name;    }    public PhoneContract setName(String name) {        this.name = name;        return this;    }    public String getPhone() {        return phone;    }    public PhoneContract setPhone(String phone) {        this.phone = phone;        return this;    }}
MessageSendor接口
public interface MessageSendor {    public void send(PhoneContract phoneContract,String message);}

public class SMSMessage implements MessageSendor {    @Override    public void send(PhoneContract phoneContract, String message) {        sendMessage(phoneContract.getName(),phoneContract.getPhone(),message);    }    private void sendMessage(String name,String address,String message){        System.out.println(String.format("%s sendMessage %s to %s %s.", this.getClass().getName(),message,name,address));    }}

public class EmailMessage implements MessageSendor {    @Override    public void send(PhoneContract phoneContract, String message) {        sendMessage(phoneContract.getName(),phoneContract.getEmail(),message);    }    private void sendMessage(String name,String address,String message){        System.out.println(String.format("%s sendMessage %s to %s %s.", this.getClass().getName(),message,name,address));    }}

MessageClient 类
public class MessageClient {    public MessageSendor getMessageSendor() {        return messageSendor;    }    public void setMessageSendor(MessageSendor messageSendor) {        this.messageSendor = messageSendor;    }    private MessageSendor messageSendor;    public MessageClient(MessageSendor sendor){       setMessageSendor(sendor);    }    public void sendMessage(PhoneContract phoneContract,String message){        if(null!=messageSendor){            messageSendor.send(phoneContract, message);        }    }}
测试类:
public class WorkClass {    public void test() {        PhoneContract phoneContract = new PhoneContract().setName("Jim").setPhone("+8613012345678").setEmail("Jim@gmail.com");        MessageSendor messageSendor = new SMSMessage();        MessageClient messageClient = new MessageClient(messageSendor);        messageClient.sendMessage(phoneContract, "hello");        messageClient.setMessageSendor(new EmailMessage());        messageClient.sendMessage(phoneContract, "lunch");    }}

测试输出:
I/System.out: com.example.qinghua_liu.myapplication.designpatten.action.SMSMessage sendMessage hello to Jim +8613012345678.I/System.out: com.example.qinghua_liu.myapplication.designpatten.action.EmailMessage sendMessage lunch to Jim Jim@gmail.com.


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