在嘗試寫更多的可測試的Java代碼,我一直使用Martin Fowler的博客上講述年前的模型 - 視圖 - 演示模式(http://martinfowler.com/eaaDev/ModelViewPresenter.html - 是啊,我知道他不贊成它,但我還是喜歡簡單)。斯卡拉工廠模式
我爲每一個的JFrame,JDialog的等視圖界面,並使用一個工廠實際生成它們,這樣我可以生成單元測試的嘲笑。
下面是一個小組樣本的類和接口的。斯卡拉比直接的語法翻譯有更好的方法嗎?換句話說,我如何使用特質,自我類型引用等來更好地遵循DRY原則並仍然編寫類型安全的代碼?
import java.awt.Dialog.ModalityType;
import java.awt.Window;
import java.awt.event.ActionListener;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import javax.swing.JButton;
import javax.swing.JDialog;
interface View {
void okButtonAddActionListener(final ActionListener actionListener);
}
class Dialog
extends JDialog
implements View {
private final JButton okButton = new JButton("OK");
public Dialog(final Window owner,
final ModalityType modalityType) {
super(owner, modalityType);
}
public void okButtonAddActionListener(final ActionListener actionListener) {
okButton.addActionListener(actionListener);
}
}
interface ViewFactory<I, C extends I> {
I newView(final Window owner,
final ModalityType modalityType)
throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException;
}
class AbstractViewFactory<I, C extends I>
implements ViewFactory<I, C> {
private final Class<C> cls;
public AbstractViewFactory(Class<C> cls) {
this.cls = cls;
}
public I newView(final Window owner,
final ModalityType modalityType)
throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
final Constructor<C> constructor = cls.getConstructor(Window.class, ModalityType.class);
return constructor.newInstance(owner, modalityType);
}
}
class DialogFactory
extends AbstractViewFactory<View, Dialog> {
private static final class InstanceHolder {
public static ViewFactory<View, Dialog> instance = new DialogFactory();
}
public DialogFactory() {
super(Dialog.class);
}
public static ViewFactory<View, Dialog> getInstance() {
return InstanceHolder.instance;
}
public static void setInstance(final ViewFactory<View, Dialog> instance) {
InstanceHolder.instance = instance;
}
}
// Here is a typical usage in production
class DialogFactoryUser {
private void userFactory() {
final Window window = new Window(null);
try {
final View view = DialogFactory.getInstance().newView(window, ModalityType.APPLICATION_MODAL);
} catch (final Exception ex) {
ex.printStackTrace();
}
}
}
// Here is a typical usage in a unit test
class Test {
public void test() {
...
mockView = createMock(View.class);
final Window window = new Window(null);
mockViewFactory = createMock(ViewFactory.class);
expect(mockViewFactory.newView(window, ModalityType.APPLICATION_MODAL)).andReturn(mockView);
...
DialogFactory.setInstance(mockViewFactory);
}
}
UPDATE::我意識到,我一個similar question去年提出,並得到了不同的「最佳」答案。看看sblundy的答案 - 非常好。
所有這些你正在做的反射東西是相當矯枉過正的(即使在Java中)。你應該在'DialogFactory'中重寫'newView'並直接調用'Dialog'構造函數。與編寫'DialogFactory'構造函數的代碼量相同,'newView'會拋出更少的異常。 – 2011-03-11 16:52:46
@Ken Bloom:我仍然試圖改進Java版本。感謝您的建議。我會看看它。 – Ralph 2011-03-11 18:01:18