Java泛型软件工程设计

Question

我有一个RabbitQueue类，它基本上像一个队列，并实现了我的Pollable接口。

我还有一个类SaveToDatabaseStrategy ，它实现了我的DataProcessingStrategy接口。 这是根据策略模式设计的。

现在，实现我的接口InputListener的类InputHandler包含Pollable接口的一个实例和DataProcessingStrategy接口之一。

但是，在声明这两个字段时，我不想设置通用类型（String），因为通用类型取决于此接口的实现，这将在以后给出。

您将如何设计？

public interface Pollable<T> {
    T poll();
}

public class RabbitQueue implements Pollable<String> {
    // code..
}

public interface DataProcessingStrategy<T> {
    void processData(T t);
}

public class SaveToDatabaseStrategy<T> implements DataProcessingStrategy<T> {

    private Repository<T, ?> repo;

    public SaveToDatabaseStrategy(Repository<T, ?> repo) {
        this.repo = repo;
    }

    @Override
    public void processData(T data) {
        repo.create(data);
        System.out.printf("Received data of type %s: %s\n", data.getClass().getSimpleName(), data);
    }
}

public interface InputListener<T> {
    void inputReceived();
    void inputReceived(T t);
}

public class InputHandler implements InputListener<String> {

    private Pollable<String> queue;
    private DataProcessingStrategy<String> strategy;

    public InputHandler(String host, String queueName) throws IOException, TimeoutException {
        queue = new RabbitQueue(host, queueName, this);
    }

    public void setStrategy(DataProcessingStrategy strategy) {
        this.strategy = strategy;
    }

    @Override
    public void inputReceived() {
        System.out.println("Input received!");
        strategy.processData(queue.poll());
    }

    @Override
    public void inputReceived(String s) {
        System.out.println("Input received: " + s + "!");
        System.out.println("> " + queue.poll());
    }
}

Answer 1

您可以将类型参数添加到InputHandler类。

public class InputHandler<T> implements InputListener<T> {

private Pollable<T> queue;
private DataProcessingStrategy<T> strategy;

public InputHandler(String host, String queueName) throws IOException, TimeoutException {
    queue = new RabbitQueue(host, queueName, this);
}

public void setStrategy(DataProcessingStrategy strategy) {
    this.strategy = strategy;
}

@Override
public void inputReceived() {
    System.out.println("Input received!");
    strategy.processData(queue.poll());
}

@Override
public void inputReceived(String s) {
    System.out.println("Input received: " + s + "!");
    System.out.println("> " + queue.poll().toString());
}
}

然后创建一个新的对象，如

new InputHandler<String>(host, queueName)