在使用Kotlin的Android数据绑定中无法将图像与图像url绑定

在Kotlin中使用数据绑定将图像url设置为图像视图时,我遇到了一些问题。

我的数据类如下:

 data class ItemInfo(val img:String,val fname:String,val lname:String){

   companion object {
    @BindingAdapter("img")
    @JvmStatic
    fun loadImage(imageView: ImageView, url: String) {
    if (url != "") {
        // Picasso.with(imageView.getContext()).load(url).resize(200, 200).into(imageView).
        Picasso.get().load(url).into(imageView)
    }

}


}
 }

我的布局如下:

<?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"
    xmlns:tools="http://schemas.android.com/tools" >

<data>
    <variable name="item"
              type="com.example.jetpackmvvmdemos.DataBindingAdapter.models.ItemInfo">
    </variable>
</data>

<androidx.cardview.widget.CardView 
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:layout_marginTop="8dp"
     android:layout_marginStart="8dp"
     android:layout_marginEnd="8dp">

   <androidx.constraintlayout.widget.ConstraintLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_margin="10dp">

   <ImageView
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:id="@+id/imageView"
        android:scaleType="fitXY"
        app:img="@{item.img}"
        app:layout_constraintStart_toStartOf="parent" 
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp" 
        app:layout_constraintEnd_toEndOf="parent" 
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp" 
        android:layout_marginTop="8dp" 
        app:layout_constraintTop_toTopOf="parent"/>
    <TextView
        android:text="@{item.fname}"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textView3" 
        app:layout_constraintStart_toStartOf="parent" 
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp" 
        app:layout_constraintEnd_toEndOf="parent" 
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp" 
        android:layout_marginTop="8dp"
        app:layout_constraintTop_toBottomOf="@+id/imageView"/>
    <TextView
        android:text="@{item.lname}"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textView4" 
        app:layout_constraintStart_toStartOf="parent" 
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp" 
        app:layout_constraintEnd_toEndOf="parent" 
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp" 
        android:layout_marginTop="8dp"
        app:layout_constraintTop_toBottomOf="@+id/textView3"/>
    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.cardview.widget.CardView>
</layout>

视图模型:

class EmpViewModel:ViewModel() {
    var empInfoList:MutableList<ItemInfo>
    init {
        empInfoList = mutableListOf<ItemInfo>()
        empInfoList.add(ItemInfo("https://via.placeholder.com/50x50.png?text=1","ABC","DEF"))
        empInfoList.add(ItemInfo("https://via.placeholder.com/50x50.png?text=2","GHI","JKL"))
        empInfoList.add(ItemInfo("https://via.placeholder.com/50x50.png?text=3","MNO","PQR"))
        empInfoList.add(ItemInfo("https://via.placeholder.com/50x50.png?text=4","STU","VWX"))

    }

}

class ListInfoAdapter(var context: Context) : RecyclerView.Adapter<ListInfoAdapter.ViewHolder>() {
    private var list: List<ItemInfo> = emptyList<ItemInfo>()

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {

        val binding: ListItemBinding = DataBindingUtil.inflate(LayoutInflater.from(context), R.layout.list_item, parent, false)
        return ListInfoAdapter.ViewHolder(binding)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
       // Log.d("ADapter", "Info:::" + list.get(position).body)
        holder.bind(list.get(position))
    }

    fun setAdapterList(list: List<ItemInfo>) {
        this.list = list
        notifyDataSetChanged()
    }
    override fun getItemCount(): Int = list.size

    class ViewHolder(val binding: ListItemBinding) : RecyclerView.ViewHolder(binding.root) {
        fun bind(data: Any) {
            binding.setVariable(BR.item, data) // BR - generated class; BR.item - 'item' is variable name declared in layout
            binding.executePendingBindings()
        }
    }
}

碎片:

class DataBindingListFragment: Fragment() {

    var fragmentView: View? = null
    private var listAdapter: ListInfoAdapter? = null
    private var listLayoutBinding: com.example.jetpackmvvmdemos.databinding.EmpInfoListFragmentLayoutBinding? = null
   // lateinit var empViewModel: EmpViewModel
    val empViewModel: EmpViewModel by lazy { ViewModelProviders.of(this).get(EmpViewModel::class.java) }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

    }


    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        listLayoutBinding = DataBindingUtil.inflate(inflater, R.layout.emp_info_list_fragment_layout, container, false)
        fragmentView = listLayoutBinding?.root
        initAdapter()
        setAdapter()
        fetchEmpInfo()
        return fragmentView
    }




    fun fetchEmpInfo() {
        listAdapter?.setAdapterList(empViewModel.empInfoList)

    }


    fun setAdapter(){
        fragmentView?.emprecyclerView?.apply {
            layoutManager = LinearLayoutManager(activity)
            addItemDecoration(DividerItemDecoration(activity, DividerItemDecoration.VERTICAL))
            adapter = listAdapter
        }
    }

    private fun initAdapter() {
        listAdapter = ListInfoAdapter(this@DataBindingListFragment.requireActivity())
    }
}

Build.Gradle(应用程序级)

     apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.2"
    defaultConfig {
        applicationId "com.example.jetpackmvvmdemos"
        minSdkVersion 15
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    dataBinding {
        enabled = true
    }
}

dependencies {
    ext.compiler_version = '3.3.1'
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.0.0-beta01'
    implementation 'androidx.core:core-ktx:1.2.0-rc01'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.1.0-alpha4'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha4'
    kapt "com.android.databinding:compiler:$compiler_version"
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'androidx.cardview:cardview:1.0.0'
    def lifecycle_version = "2.1.0"
    // ViewModel and LiveData
    implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
    implementation 'com.squareup.picasso:picasso:2.71828'
}
kapt {
    generateStubs = true
}