标签：android picasso android-databinding
我想用绑定创建一个电影海报图像的网格视图.
我的viewmodel看起来像这样：
public class PopularMoviesViewModel extends BaseObservable {
Movie movie;
Context context;
MovieServiceComponent movieServiceComponent = DaggerMovieServiceComponent.builder()
.contextModule(new ContextModule(context))
.build();
Picasso getPicasso = movieServiceComponent.getPicasso();
public PopularMoviesViewModel(Movie movie, Context context) {
this.movie = movie;
this.context = context;
}
@Bindable
public String getImageUrl(){
return movie.posterPath();
}
@Bindable
public String getTitle(){
return movie.originalTitle();
}
@BindingAdapter({"imageUrl"})
public void setImageUrl(ImageView view, String poserPath){
getPicasso.with(view.getContext()).load("http://image.tmdb.org/t/p/w185"+ poserPath).into(view);
}
}
布局：
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android">
<data class="PopularMoviesBinding">
<variable
name="pmvm"
type="com.hartyandi.oviesm.modelviews.PopularMoviesViewModel"></variable>
</data>
<LinearLayout
android:id="@+id/row"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
android:paddingBottom="0dp"
android:paddingTop="5dp"
android:paddingRight="2.5dp"
android:paddingLeft="5dp"
android:orientation="vertical">
<ImageView
app:imageUrl="@{pmvm.imageUrl}"
android:id="@+id/popular_movies_grid_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="0dp"
android:adjustViewBounds="true"
android:elevation="20dp">
</ImageView>
<TextView
android:id="@+id/popular_movies_grid_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{pmvm.title}"
android:textColor="#000000"
android:textSize="12sp"
android:background="#FFFFFF"
>
</TextView>
</LinearLayout>
</layout>
适配器：
public class PopularMoviesAdapter extends RecyclerView.Adapter<PopularMoviesAdapter.BindingHolder> {
private List<Movie> movies;
private Context context;
public PopularMoviesAdapter(List<Movie> movies, Context context) {
this.movies = movies;
this.context = context;
}
public void add(Movie movie){
movies.add(movie);
}
@Override
public BindingHolder onCreateViewHolder(ViewGroup parent, int viewType) {
PopularMoviesBinding popularMoviesBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()),
R.layout.popular_movies_gridview_row, parent,false);
return new BindingHolder(popularMoviesBinding);
}
@Override
public void onBindViewHolder(PopularMoviesAdapter.BindingHolder holder, int position) {
PopularMoviesBinding popularMoviesBinding = holder.popularMoviesBinding;
popularMoviesBinding.setPmvm(new PopularMoviesViewModel(movies.get(position), context));
}
@Override
public int getItemCount() {
return movies.size();
}
public class BindingHolder extends RecyclerView.ViewHolder{
private PopularMoviesBinding popularMoviesBinding;
public BindingHolder(PopularMoviesBinding popularMoviesBinding) {
super(popularMoviesBinding.getRoot());
this.popularMoviesBinding = popularMoviesBinding;
}
}
}
我收到以下错误：
java.lang.IllegalStateException: Required DataBindingComponent is null in class PopularMoviesBinding.A BindingAdapter in modelviews.PopularMoviesViewModel is not static and requires an object to use, retrieved from the DataBindingComponent.
I tried to change my implementation just like this stackoverflow post suggest,我得到了相同的错误消息.
I also used the following code as example.
有人可以解释代码的问题,以及如何解决它？
解决方法:
您可能不打算为BindingAdapter使用实例方法.
如果这样做,则必须提供DataBindingComponent,以便生成的Binding类知道要使用的实例.
您有两个选项 – 提供DataBindingComponent或仅将所需的上下文作为属性传递给静态绑定适配器方法.第二个更容易理解,所以我将从那开始：
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android">
<data class="PopularMoviesBinding">
<variable name="pmvm"
type="com.hartyandi.oviesm.modelviews.PopularMoviesViewModel"/>
<variable name="picasso" type="com.whatever.Picasso"/>
</data>
<!-- ... -->
<ImageView
app:imageUrl="@{pmvm.imageUrl}"
app:picasso="@{picasso}"
... />
</ImageView>
</layout>
然后在你的BindingAdapter中：
@BindingAdapter({"imageUrl", "picasso"})
public static void setImageUrl(ImageView view, String poserPath, Picasso picasso){
picasso.with(view.getContext()).load("http://image.tmdb.org/t/p/w185"+ poserPath).into(view);
}
请注意,setImageUrl现在是静态的.
或者,由于您的Picasso实例也在ViewModel上,您可以通过为毕加索添加一个getter来传递实例：
<ImageView
app:imageUrl="@{pmvm.imageUrl}"
app:picasso="@{pmvm.picasso}"
... />
和ViewModel中的方法：
public Picasso getPicasso() { return this.getPicasso; }
另一种方式意味着您实现了DataBindingComponent.当您创建实例BindingAdapter方法时,生成的接口将为您的类提供一个getter.您需要创建一个类来实现该接口：
public class MyDataBindingComponent implements DataBindingComponent {
public PopularMoviesViewModel getPopularMoviesViewModel() {
return whateverIDoToCreateOrGetThisBindingAdapterInstance();
}
}
然后在膨胀或绑定时传递实例：
PopularMoviesBinding popularMoviesBinding =
DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()),
R.layout.popular_movies_gridview_row, parent,false,
new MyDataBindingComponent());
标签：android,picasso,android-databinding 来源： https://codeday.me/bug/20190611/1218136.html
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