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委托模式

委托模式，就是一个类将部分功能（也可以是全部功能）委托给另一个类

比如一个机器人（Person），可以说（speak）也可以听（hear）

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interface SpeakDelegate { void speak(String text); }
interface HearDelegate { void hear(String text); }
  
class Robot {
    SpeakDelegate speakDelegate;
    HearDelegate  hearDelegate;
    void speak(String text) { speakDelegate.speak(text); }
    void hear(String text) { hearDelegate.hear(text); }
}

class MyRobotBehaviour implements SpeakDelegate, HearDelegate {
    String name = 'Jack';

    void speak(String text) {
        System.out.format('My name is %s. I speak %s\n', name, text)
    }
  
    void hear(String text) {
        System.out.format('My name is %s. I hear %s\n', name, text)
    }
}

Robot robot = new Robot();
MyRobotBehaviour myRobotBehaviour = new MyRobotBehaviour()
robot.speakDelegate = myRobotBehaviour;
robot.hearDelegate  = myRobotBehaviour;

当然也可以全权委托，看起来和代理类似，但代理一般是不能变更被代理的对象的，而委托可以修改委托对象

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interface RobotDelegate { void speak(String text); void hear(String text); }
  
class Robot {
    RobotDelegate delegate;
    void speak(String text) { delegate.speak(text); }
    void hear(String text) { delegate.hear(text); }
}

class MyRobotBehaviour implements RobotDelegate {
    String name = 'Jack';

    void speak(String text) {
        System.out.format('My name is %s. I speak %s\n', name, text)
    }
  
    void hear(String text) {
        System.out.format('My name is %s. I hear %s\n', name, text)
    }
}

Robot robot = new Robot();
MyRobotBehaviour myRobotBehaviour = new MyRobotBehaviour()
robot.delegate = myRobotBehaviour;
  技术 / 设计模式