java - 使用数据绑定(bind)更改背景图像

Question

在 gradle 中我启用了数据绑定(bind)。尝试更改背景图片后，当我运行应用程序时，我在日志中观察到以下错误:

Error:Execution failed for task ':app:compileDebugJavaWithJavac'.
java.lang.RuntimeException: Found data binding errors.
****/ data binding error ****msg:Identifiers must have user defined types from the XML file. ImageBacground is missing it
file:D:\Bogv\Android project\Pote\app\src\main\res\layout\fragment1.xml
loc:13:19 - 13:32
****\ data binding error ****

我的 View 类:

    public class ImageBacground {
    private ImageView imageView;

    public ImageBacground(ImageView imageView) {
        this.imageView = imageView;

    }
   @BindingAdapter({"android:src"})
    public static void loadImage(ImageView view, String imageUrl) {
        Picasso.with(view.getContext())
                .load(imageUrl)
                .placeholder(R.drawable.potehki_fon)
                .into(view);
    }

    public ImageView getImageView() {
        return imageView;
    }

    public void setImageView(ImageView imageView) {
        this.imageView = imageView;
    }
}

XML

    <?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <import type="android.view.View" />
        <variable name="images" type="com.retrofa.potehkilulibalse.images.ImageBacground"/>
    </data>
<LinearLayout
    android:id="@+id/first_activity"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="2dp"
    android:gravity="center"
    android:orientation="horizontal"
    android:src="@{ImageBacground.loadImage,default=@drawable/potehki_fon}"
    android:theme="@style/AppTheme.NoActionBar"

    >

    <ImageView

        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="50dp"
        android:layout_weight="1"
        android:clickable="true"
        android:src="@drawable/eda" />

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="70dp"
        android:layout_weight="1"
        android:clickable="true"
        android:src="@drawable/umivanie" />

    <ImageView
        android:id="@+id/imageView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="50dp"
        android:layout_weight="1"
        android:clickable="true"
        android:src="@drawable/son" />
</LinearLayout>
</layout>

Answer 1

您需要创建自定义绑定(bind)适配器

 public class CustomBinding {

   @BindingAdapter({"imageUrl"})
   public static void loadImage(LinearLayout layout, Drawable drawable) {
       if (drawable != null) {
           if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
               layout.setBackground(drawable);
           } else {
               layout.setBackgroundDrawable(drawable);
           }
       }
   }
}

然后在xml中你可以这样使用

activity_main.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto">
     <LinearLayout
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:orientation="vertical"
       app:imageUrl="@{@drawable/ic_android_black_24dp}">
    </LinearLayout>
 </layout>

现在，在 Activity 文件的onCreate()方法中绑定(bind)xml布局

DataBindingUtil.setContentView(this, R.layout.activity_main);