使用Android中的数据绑定在Android：src中为ImageView设置可提取的资源ID

Question

我试图使用数据绑定将可提取的资源ID设置为ImageView的Android：src

下面是我的目标：

public class Recipe implements Parcelable {
    public final int imageResource; // resource ID (e.g. R.drawable.some_image)
    public final String title;
    // ...

    public Recipe(int imageResource, String title /* ... */) {
        this.imageResource = imageResource;
        this.title = title;
    }

    // ...
}

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <variable
            name="recipe"
            type="com.example.android.fivewaystocookeggs.Recipe" />
    </data>

    <!-- ... -->

    <ImageView
        android:id="@+id/recipe_image_view"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:scaleType="centerCrop"
        android:src="@{recipe.imageResource}" />

    <!-- ... -->

</layout>

// ...

public class RecipeActivity extends AppCompatActivity {

    public static final String RECIPE_PARCELABLE = "recipe_parcelable";
    private Recipe mRecipe;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mRecipe = getIntent().getParcelableExtra(RECIPE_PARCELABLE);
        ActivityRecipeBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_recipe);
        binding.setRecipe(mRecipe);
    }

    // ...

}

它根本不显示图像。我做错了什么？

顺便说一句，它完美地使用了标准方式：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_recipe);

    final ImageView recipeImageView = (ImageView) findViewById(R.id.recipe_image_view);
    recipeImageView.setImageResource(mRecipe.imageResource);

}

Answer 1

截至2016年11月10日的答复

Splash下面的注释强调了不必使用自定义属性类型（如ImageResource)，我们可以为Android:src创建多个方法，如下所示：

public class DataBindingAdapters {

    @BindingAdapter("android:src")
    public static void setImageUri(ImageView view, String imageUri) {
        if (imageUri == null) {
            view.setImageURI(null);
        } else {
            view.setImageURI(Uri.parse(imageUri));
        }
    }

    @BindingAdapter("android:src")
    public static void setImageUri(ImageView view, Uri imageUri) {
        view.setImageURI(imageUri);
    }

    @BindingAdapter("android:src")
    public static void setImageDrawable(ImageView view, Drawable drawable) {
        view.setImageDrawable(drawable);
    }

    @BindingAdapter("android:src")
    public static void setImageResource(ImageView imageView, int resource){
        imageView.setImageResource(resource);
    }
}

旧答案

public class DataBindingAdapters {

    @BindingAdapter("imageResource")
    public static void setImageResource(ImageView imageView, int resource){
        imageView.setImageResource(resource);
    }
}

<ImageView
    android:id="@+id/recipe_image_view"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:scaleType="centerCrop"
    imageResource="@{recipe.imageResource}" />

DataBindingAdapters类不需要在任何地方声明，数据绑定机制无论如何都会找到它（我相信）