使用 Android 中的数据绑定在 android:src 中为 ImageView 设置可绘制资源 ID

问题描述

我正在尝试使用数据绑定将可绘制资源 ID 设置为 ImageView 的 android:src

这是我的对象:

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;
    }

    // ...
}

这是我的布局:

<?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>

最后是活动类:

// ...

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?

It doesn't display image at all. What am I doing wrong?

顺便说一句，它与标准方式完美配合:

BTW, it was perfectly working with standard way:

@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);

}

推荐答案

截至 2016 年 11 月 10 日的答复

下面的Splash评论强调了没有必要使用自定义属性类型(如imageResource)，我们可以像这样为android:src创建多个方法:

Splash's comment below has highlighted that it is not necessary to use a custom property type (like imageResource), we can instead create multiple methods for android:src like so:

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

您可以随时尝试使用适配器:

You could always try to use an adapter:

public class DataBindingAdapters {

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

然后您可以像这样在 xml 中使用适配器

You can then use the adapter in your xml like so

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

一定要注意xml里面的名字要匹配BindingAdapter注解(imageResource)

DataBindingAdapters 类不需要在任何地方特别声明，DataBinding 机制无论如何都会找到它(我相信)

The DataBindingAdapters class doesn't need to be declared anywhere in particular, the DataBinding mechanics will find it no matter (i believe)

这篇关于使用 Android 中的数据绑定在 android:src 中为 ImageView 设置可绘制资源 ID的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！