Square Flow + Mortar平板电脑示例

Question

我一直在使用流和砂浆作为Android应用的替代架构进行试验。我一直在研究一款应用程序，该应用程序当前只有一种电话布局，但我想知道如果您想为平板电脑设置不同的布局，流程和迫击炮架构如何工作。主细节可能是最简单的例子，但显然还有其他例子。

我有一些想法如何工作，但我想知道广场开发人员可能已经考虑过这个话题。

Answer 1

我们仍在为此做出规范的回答，但基本思路是让资源系统更改您在哪种情况下显示的视图。因此，您的活动将其内容视图设置为R.layout.root_view。该布局的平板电脑版本（我们将其放在res/layout-sw600dp中）可以绑定到不同的视图，这可能会注入不同的演示者，等等。

很多情况下你需要做一个决定运行的情况下，定义values/bools .xml

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
    <bool name="show_tablet_ui">false</bool> 
</resources> 

和values-sw600dp/bools.xml

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
    <bool name="show_tablet_ui">true</bool> 
</resources> 

一个布尔资源将其暴露在通过匕首应用程序的其余部分。使用此绑定注释：

/** 
* Whether we should show a tablet UI. 
*/ 
@Retention(RUNTIME) @Qualifier 
public @interface ShowTabletUi { 
    int ID = R.bool.show_tablet_ui; 
} 

和提供方法，如：

/** 
* Singleton because there's no reason to read it from resources again, 
* it won't change. 
*/ 
@Provides @ShowTabletUi @Singleton boolean showTabletUi(Resources resources) { 
    return resources.getBoolean(ShowTabletUi.ID); 
} 

别急还有更多！假设你想要一个单一的屏幕/蓝图定义，为不同的外形因素制造不同的模块。我们已经开始使用注解方案来简化这种事情。我们已经开始使用一些注释来声明它们的接口类，而不是让我们的屏幕类全部实现BluePrint。在这个世界里，屏幕如何有选择地选择用于平板电脑或手机的模块。

@Layout(R.layout.some_view) @WithModuleFactory(SomeScreen.ModuleFactory.class) 
public class SomeScreen { 
    public static class ModuleFactory extends ResponsiveModuleFactory<HomeScreen> { 
    @Override protected Object createTabletModule(HomeScreen screen) { 
    return new TabletModule(); 
    } 

    @Override protected Object createMobileModule(HomeScreen screen) { 
    return new MobileModule(); 
    } 
} 

魔法吧？这是幕后的内容。首先，一个ModuleFactory是一些静态类，可以访问屏幕和资源，并吐出一个匕首模块。

public abstract class ModuleFactory<T> { 
    final Blueprint createBlueprint(final Resources resources, final MortarScreen screen) { 
    return new Blueprint() { 
     @Override public String getMortarScopeName() { 
     return screen.getName(); 
     } 

     @Override public Object getDaggerModule() { 
     return ModuleFactory.this.createDaggerModule(resources, (T) screen); 
     } 
    }; 
    } 

    protected abstract Object createDaggerModule(Resources resources, T screen); 
} 

我们的trixie ResponsiveModuleFactory子类看起来像这样。 （记住怎样ShowTabletUi.java定义的资源ID作为常数？这是为什么。）

public abstract class ResponsiveModuleFactory<T> extends ModuleFactory<T> { 

    @Override protected final Object createDaggerModule(Resources resources, T screen) { 
    boolean showTabletUi = resources.getBoolean(ShowTabletUi.ID); 
    return showTabletUi ? createTabletModule(screen) : createMobileModule(screen); 
    } 

    protected abstract Object createTabletModule(T screen); 

    protected abstract Object createMobileModule(T screen); 
} 

为了让这一切都走了，我们有一个ScreenScoper类（如下图）。在Mortar示例代码中，您将使ScreenConductor使用其中的一个来创建和销毁示波器。迟早（很快我希望）迫击炮和/或其样本将被更新以包含这些东西。

package mortar; 

import android.content.Context; 
import android.content.res.Resources; 
import com.squareup.util.Objects; 
import dagger.Module; 
import java.lang.reflect.Constructor; 
import java.lang.reflect.InvocationTargetException; 
import java.util.LinkedHashMap; 
import java.util.Map; 

import static java.lang.String.format; 

/** 
* Creates {@link MortarScope}s for screens that may be annotated with {@link WithModuleFactory}, 
* {@link WithModule} or {@link Module}. 
*/ 
public class ScreenScoper { 
    private static final ModuleFactory NO_FACTORY = new ModuleFactory() { 
    @Override protected Object createDaggerModule(Resources resources, Object screen) { 
     throw new UnsupportedOperationException(); 
    } 
    }; 

    private final Map<Class, ModuleFactory> moduleFactoryCache = new LinkedHashMap<>(); 

    public MortarScope getScreenScope(Context context, final MortarScreen screen) { 
    MortarScope parentScope = Mortar.getScope(context); 
    return getScreenScope(context.getResources(), parentScope, screen); 
    } 

    /** 
    * Finds or creates the scope for the given screen, honoring its optoinal {@link 
    * WithModuleFactory} or {@link WithModule} annotation. Note the scopes are also created 
    * for unannotated screens. 
    */ 
    public MortarScope getScreenScope(Resources resources, MortarScope parentScope, 
     final MortarScreen screen) { 
    ModuleFactory moduleFactory = getModuleFactory(screen); 
    MortarScope childScope; 
    if (moduleFactory != NO_FACTORY) { 
     Blueprint blueprint = moduleFactory.createBlueprint(resources, screen); 
     childScope = parentScope.requireChild(blueprint); 
    } else { 
     // We need every screen to have a scope, so that anything it injects is scoped. We need 
     // this even if the screen doesn't declare a module, because Dagger allows injection of 
     // objects that are annotated even if they don't appear in a module. 
     Blueprint blueprint = new Blueprint() { 
     @Override public String getMortarScopeName() { 
      return screen.getName(); 
     } 

     @Override public Object getDaggerModule() { 
      return null; 
     } 
     }; 
     childScope = parentScope.requireChild(blueprint); 
    } 
    return childScope; 
    } 

    private ModuleFactory getModuleFactory(MortarScreen screen) { 
    Class<?> screenType = Objects.getClass(screen); 
    ModuleFactory moduleFactory = moduleFactoryCache.get(screenType); 

    if (moduleFactory != null) return moduleFactory; 

    WithModule withModule = screenType.getAnnotation(WithModule.class); 
    if (withModule != null) { 
     Class<?> moduleClass = withModule.value(); 

     Constructor<?>[] constructors = moduleClass.getDeclaredConstructors(); 

     if (constructors.length != 1) { 
     throw new IllegalArgumentException(
      format("Module %s for screen %s should have exactly one public constructor", 
       moduleClass.getName(), screen.getName())); 
     } 

     Constructor constructor = constructors[0]; 

     Class[] parameters = constructor.getParameterTypes(); 

     if (parameters.length > 1) { 
     throw new IllegalArgumentException(
      format("Module %s for screen %s should have 0 or 1 parameter", moduleClass.getName(), 
       screen.getName())); 
     } 

     Class screenParameter; 
     if (parameters.length == 1) { 
     screenParameter = parameters[0]; 
     if (!screenParameter.isInstance(screen)) { 
      throw new IllegalArgumentException(format("Module %s for screen %s should have a " 
        + "constructor parameter that is a super class of %s", moduleClass.getName(), 
       screen.getName(), screen.getClass().getName())); 
     } 
     } else { 
     screenParameter = null; 
     } 

     try { 
     if (screenParameter == null) { 
      moduleFactory = new NoArgsFactory(constructor); 
     } else { 
      moduleFactory = new SingleArgFactory(constructor); 
     } 
     } catch (Exception e) { 
     throw new RuntimeException(
      format("Failed to instantiate module %s for screen %s", moduleClass.getName(), 
       screen.getName()), e); 
     } 
    } 

    if (moduleFactory == null) { 
     WithModuleFactory withModuleFactory = screenType.getAnnotation(WithModuleFactory.class); 
     if (withModuleFactory != null) { 
     Class<? extends ModuleFactory> mfClass = withModuleFactory.value(); 

     try { 
      moduleFactory = mfClass.newInstance(); 
     } catch (Exception e) { 
      throw new RuntimeException(format("Failed to instantiate module factory %s for screen %s", 
       withModuleFactory.value().getName(), screen.getName()), e); 
     } 
     } 
    } 

    if (moduleFactory == null) moduleFactory = NO_FACTORY; 

    moduleFactoryCache.put(screenType, moduleFactory); 

    return moduleFactory; 
    } 

    private static class NoArgsFactory extends ModuleFactory<Object> { 
    final Constructor moduleConstructor; 

    private NoArgsFactory(Constructor moduleConstructor) { 
     this.moduleConstructor = moduleConstructor; 
    } 

    @Override protected Object createDaggerModule(Resources resources, Object ignored) { 
     try { 
     return moduleConstructor.newInstance(); 
     } catch (InstantiationException | IllegalAccessException | InvocationTargetException e) { 
     throw new RuntimeException(e); 
     } 
    } 
    } 

    private static class SingleArgFactory extends ModuleFactory { 
    final Constructor moduleConstructor; 

    public SingleArgFactory(Constructor moduleConstructor) { 
     this.moduleConstructor = moduleConstructor; 
    } 

    @Override protected Object createDaggerModule(Resources resources, Object screen) { 
     try { 
     return moduleConstructor.newInstance(screen); 
     } catch (InstantiationException | IllegalAccessException | InvocationTargetException e) { 
     throw new RuntimeException(e); 
     } 
    } 
    } 
}