如何在Java中包装抽象类层次结构

Question

我正在编写一个包装另一个库（dependentLibrary）的所有类的库（wrapperLibrary），我想强制集成器只使用wrapperLibrary中的类而不是依赖于来自LibLibrary的类 - 将它包装起来。

我试图找到一种方法来包装dependentLibrary的下面的Abstract层次结构：

public abstract class AOT{
    // Has few abstract methods and few default method implementation
}

public abstract class AMOT extends AOT {
    // Has a new abstract method and few overridden methods
}

public class COTM extends AMOT{
    // Implementation class of the abstract hierarchy
}

包装器应如下所示：

public abstract class AOTWrapper{
    // Has the default method implementation of AOT
}

public abstract class AMOTWrapper extends AOTWrapper {
    // Has the default method implementation of AMOT
}

public class COTMWrapper extends AMOTWrapper{
    // Implementation class of the abstract hierarchy
}

wrapperLibrary的集成商或消费者不应该访问AOT / AMOT / COTM。

dependentLibrary中的其他类也有AOT / AMOT / COTM作为方法参数或返回类型。因此，我们应该能够在需要时将AOTWrapper转换为AOT。

我们怎么能实现这个目标？

Answer 1

这实际上不是通常称为特定设计模式的包装器。它要求包装器和包装类实现相同的接口，但实际上你可以通过所有包装器的抽象父扩展lib的最后一个子具体类并覆盖所有相关方法，你意识到在这种情况下所有包装器都将继承所有libs方法，但你可以通过异常抛出覆盖不必要的东西（例如，你可以在java.util.AbstractList的某些方法中找到类似的技巧）。然后，可能很好的解决方案是使用一个工厂，它将正确创建你的lib实例，放到包装器并在他喜欢的任何类容器中提供给客户。会是这样的：

public class Main {

    public static void main(String[] args) {

        WrapperFactory wrapperFactory = new WrapperFactory();
        COTMWrapper cotmWrapper = wrapperFactory.getWrapper(COTMWrapper.class);
        cotmWrapper.doCOTMStuff();
        cotmWrapper.doSomethingElse();
        AMOTWrapper amotWrapper = cotmWrapper;
        amotWrapper.doAOTStuff();
        AOTWrapper aotWrapper = amotWrapper;
        aotWrapper.doAOTStuff();
        AOT likeNotWrapped = cotmWrapper;
        likeNotWrapped.doSomething();
    }

}
 class WrapperFactory {

    public <T extends AOTWrapper> T  getWrapper(Class<T> type){
        COTM cotm = new COTM();
        return type.cast(new COTMWrapper(cotm));
    }
}

abstract class AOT {
    // Has few abstract methods and few default method implementation
    public abstract void doSomething();

    public void doAOTStuff() {
        // AOT stuff is doing
    }

}

abstract class AMOT extends AOT {
    // Has a new abstract method and few overridden methods
    public abstract void doSomethingElse();

    public void doSomething() {
        // AMOT stuff is doing
    }

}

class COTM extends AMOT {
    // Implementation class of the abstract hierarchy

    public void doSomethingElse() {
        doCOTMStuff();
    }

    public void doCOTMStuff() {
        // COTM stuff is doing
    }
}

abstract class AOTWrapper extends COTM {

    private AOT container;

    public AOTWrapper(AOT container) {
        this.container = container;
    }

    @Override
    public void doAOTStuff() {
        container.doAOTStuff();
    }

     @Override
    public void doCOTMStuff() {
        throw new UnsupportedOperationException();
    }

    @Override
    public void doSomething() {
        throw new UnsupportedOperationException();
    }

    @Override
    public void doSomethingElse() {
        throw new UnsupportedOperationException();
    }
    // Has the default method implementation of AOT
}

abstract class AMOTWrapper extends AOTWrapper {

    private AMOT container;

    public AMOTWrapper(AMOT container) {
        super(container);
        this.container = container;
    }

    @Override
    public void doSomething() {
        container.doSomething();
    }

    // Has the default method implementation of AMOT
}

class COTMWrapper extends AMOTWrapper {

    private COTM container;

    public COTMWrapper(COTM container) {
        super(container);
        this.container = container;
    }

    @Override
    public void doSomethingElse() {
        container.doSomethingElse();
    }

    @Override
    public void doCOTMStuff() {
        container.doCOTMStuff();
        // COTM stuff is doing
    }
//     Implementation class of the abstract hierarchy
}

另一种方法：

public class Main {

    public static void main(String[] args) {

        COTMWrapper cotmWrapper = new COTMWrapper();
        AMOTInter amotWrapper = cotmWrapper;
        amotWrapper.doSomethingElse();
        AOT likeNotWrapped = cotmWrapper;
        likeNotWrapped.doSomething();
    }

}


abstract class AOT {
    // Has few abstract methods and few default method implementation
    public abstract void doSomething();

    public void doAOTStuff() {
        // AOT stuff is doing
    }

}

abstract class AMOT extends AOT {
    // Has a new abstract method and few overridden methods
    public abstract void doSomethingElse();

    public void doSomething() {
        // AMOT stuff is doing
    }

}

class COTM extends AMOT {
    // Implementation class of the abstract hierarchy

    public void doSomethingElse() {
        doCOTMStuff();
    }

    public void doCOTMStuff() {
        // COTM stuff is doing
    }
}

abstract class AOTWrapper extends AOT implements AOTInterface {

    @Override
    public void doAOTStuff() {
        super.doAOTStuff();
    }

    // Has the default method implementation of AOT
}

abstract class AMOTWrapper extends AMOT implements AMOTInter {

       @Override
    public void doSomething() {
        super.doSomething();
    }

    // Has the default method implementation of AMOT
}

class COTMWrapper extends COTM implements COTMInter {

    @Override
    public void doSomethingElse() {
        super.doSomethingElse();
    }

    @Override
    public void doCOTMStuff() {
        super.doCOTMStuff();
    }
//     Implementation class of the abstract hierarchy
}


interface AOTInterface {

    void doSomething();

    void doAOTStuff();
}

interface AMOTInter extends AOTInterface {

    void doSomethingElse();

    void doSomething();
}

interface COTMInter extends AMOTInter {

    void doSomethingElse();

    void doCOTMStuff();
}

祝好运！