Java

Question

不确定这是否可行，但我遇到过两个接口具有相同方法的情况。这些是给定的接口，所以我无法更改它们。

给定接口

interface SomeGivenService {
    boolean authenticate(String username, String password);
    Object someSpecialMethod(Object param);
}

interface AnotherGivenService {
    boolean authenticate(String username, String password);
    String aGreatMethod();
    String sayHello();
}

为了使用此服务，我创建了一个 class 并做了一些处理以防此服务抛出错误。

class SomeGivenServiceConsumer {

    SomeGivenService a;

    public SomeGivenServiceConsumer(SomeGivenService a) {
        this.a = a;
    }

    public authenticate(MyUserPassBean bean) {
        try {
            a.authenticate(bean.username, bean.password);
        } catch (Exception e) {
            throw new MyException();
        }
        ...
    }
}

class AnotherGivenServiceConsumer {

    AnotherGivenService a;

    public AnotherGivenServiceConsumer(AnotherGivenService a) {
        this.a = a;
    }

    public authenticate(MyUserPassBean bean) {
        try {
            a.authenticate(bean.username, bean.password);
        } catch (Exception e) {
            throw new MyException();
        }
        ...
    }
}

是否可以在我的消费者中避免这种代码重复？我可能会有很多，并且想避免这种重复的代码。我最初想更改我的消费者以接收实现此身份验证的接口，但由于我无法更改给定的接口，因此不确定这是否可能。

是否可以使用 "Generic interface which has a method?" 或使用某种设计模式？有任何想法吗？我在尝试什么：

class AnotherGivenServiceConsumer {

    AnotherGivenService a;
    GivenServiceAuthenticable b;

    public AnotherGivenServiceConsumer(AnotherGivenService a, 
                                       GivenServiceAuthenticable b) {
        this.a = a;
        this.b = b;
    }

    public authenticate(MyUserPassBean bean) throws MyException {
        return b.authenticate(bean.username, bean.password);
    }
}

interface GivenServiceAuthenticable<T> {
    boolean authenticate(T givenService, MyUserPassBean bean);
}

class GivenServiceAuthenticableImpl<T> implements GivenServiceAuthenticable<T> {
    boolean authenticate(T givenService, MyUserPassBean bean) {
        try {
            //this won't compile as it's a generic class..
            t.authenticate(bean.username, bean.password); 
        } catch (Exception e) {
            throw new MyException();
        }
        ...
    }
}

另一个问题是如果我不能改变它来实现我的新对象，如何实例化这个对象？

Answer 1

你需要做的就是使用继承。然后处理超类中的错误即

    class SomeGivenServiceConsumer {

        SomeGivenService a;
        AnotherGivenService b;

        public SomeGivenServiceConsumer(SomeGivenService a) {
            this.a = a;
            try{
             authenticate(MyUserPassBean);
            }catch (Exception e) {
            System.out.println("Thrown exception has been caught : "+e.getMessage());
            }
        }

        public authenticate(MyUserPassBean bean) throws MyException {
                //your implementation here
        }
    }    
    class AnotherGivenServiceConsumer extends SomeGivenServiceConsumer{

        public AnotherGivenServiceConsumer(AnotherGivenService b) {
            super(someGivenService);//construct superclass
            authenticate(MyUserPassBean);//call subclass authenticate method
        }

        @override
        public authenticate(MyUserPassBean bean) throws MyException {
                super.authenticate(MyUserPassBean);//call superclass method
                //your implementation here

        }
    }

然后你构造子类：

public static void main(String[] args) {
    new AnotherGivenServiceConsumer(AnotherGivenService);
}

Answer 2

您可以使用 template pattern 在基础 class 中实现通用功能，同时将单个可变行委托给 subclasses:

abstract class ConsumerBase {
    public void authenticate(MyUserPassBean bean) {
        try {
            authenticate(bean.username, bean.password);
        } catch (Exception e) {
            throw new MyException();
        }
        //...
    }

    protected abstract boolean authenticate(String username, String password);
}

class SomeGivenServiceConsumer extends ConsumerBase {

    SomeGivenService a;

    public SomeGivenServiceConsumer(SomeGivenService a) {
        this.a = a;
    }

    @Override
    protected boolean authenticate(String username, String password) {
        return a.authenticate(username, password);
    }
}

class AnotherGivenServiceConsumer extends ConsumerBase {

    AnotherGivenService a;

    public AnotherGivenServiceConsumer(AnotherGivenService a) {
        this.a = a;
    }

    @Override
    protected boolean authenticate(String username, String password) {
        return a.authenticate(username, password);
    }
}

Java - 概括不同的类，相似的方法（不改变sub类？）

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