关于java:桥接模式的示例

依据不同的告警规定，触发不同类型的告警。告警反对多种告诉渠道，包含：邮件、短信、微信、主动语音电话。告诉的紧急水平有多种类型，包含：SEVERE（重大）、URGENCY（紧急）、NORMAL（一般）、TRIVIAL（无关紧要）。不同的紧急水平对应不同的告诉渠道。比方，SERVE（重大）级别的音讯会通过“主动语音电话”告知相干人员。

import java.util.List;

public enum NotificationEmergencyLevel {SEVERE, URGENCY, NORMAL, TRIVIAL}

class Notification{
    private List emailAddresses;
    private List telephones;
    private List wechatIds;
    public Notification() {}

    public void setEmailAddress(List emailAddress) {this.emailAddresses = emailAddress;}
    public void setTelephones(List telephones) {this.telephones = telephones;}
    public void setWechatIds(List wechatIds) {this.wechatIds = wechatIds;}

    public void notify(NotificationEmergencyLevel level,String message){if (level.equals(NotificationEmergencyLevel.SEVERE)){// 电话告诉}else if (level.equals(NotificationEmergencyLevel.URGENCY)){// 微信}else  if (level.equals(NotificationEmergencyLevel.NORMAL)){// 邮件}else if (level.equals(NotificationEmergencyLevel.TRIVIAL)){// 邮件}
    }
}


// 客户端如何应用
class ErrorAlertHandler extends AlertHandler {public ErrorAlertHandler(AlertRule rule, Notification notification){super(rule, notification);
    }
    @Override
    public void check(ApiStatInfo apiStatInfo){if (apiStatInfo.getErrorCount() > rule.getMatchedRule(apiStatInfo.getApi()).getMaxErrorCount()){notification.notify(NotificationEmergencyLevel.SEVERE, "...");
        }
    }
}

/*Notification 类有一处显著的问题就是应用的 if 太多了，另外 if 里的是发送报警逻辑会很简单，咱们将不同渠道的发送逻辑剥离进去，造成独立的音讯发送类（MsgSender 相干类）。其中，Notification 类相当于形象，MsgSender 类相当于实现，两者能够独立开发，通过组合关系（也就是桥梁）任意组合在一起 */

--------------- 改良版本 -------------

interface MsgSender{void send(String message);
}

class TelephoneMsgSender implements MsgSender{
    private List telephones;
    public TelephoneMsgSender(List telephones) {this.telephones = telephones;}
    @Override
    public void send(String message) {//...}
}
class EmailMsgSender implements MsgSender {// 与 TelephoneMsgSender 代码构造相似，所以省略...}
class WechatMsgSender implements MsgSender {// 与 TelephoneMsgSender 代码构造相似，所以省略...}

abstract class Notification {
    protected MsgSender msgSender;

    public Notification(MsgSender msgSender) {this.msgSender = msgSender;}

    public abstract void notify(String message);
}

class SevereNotification extends Notification {public SevereNotification(MsgSender msgSender){super(msgSender);
    }

    @Override
    public void notify(String message) {msgSender.send(message);
    }
}

class UrgencyNotification extends Notification {// 与 SevereNotification 代码构造相似，所以省略...}
    
class NormalNotification extends Notification {// 与 SevereNotification 代码构造相似，所以省略...}

class TrivialNotification extends Notification {// 与 SevereNotification 代码构造相似，所以省略...}