所以，在 Kotlin 中一步一步来。
我的 json 文件（在 res > raw > people.json 中）：
{
"0": {
"image_path": "https://images.unsplash.com/photo-1485199692108-c3b5069de6a0?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1000&q=80",
"title": "Girl 1"
},
"1": {
"image_path": "https://images.unsplash.com/photo-1520065949650-380765513210?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1000&q=80",
"title": "Girl 2"
},
"2": {
"image_path": "https://images.unsplash.com/photo-1547513609-d80733850d2e?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1000&q=80",
"title": "Girl 3"
},
"3": {
"image_path": "https://images.unsplash.com/photo-1550094195-2234fa4e2128?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1000&q=80",
"title": "Girl 4"
},
"size": "4"
}
活动布局 (res > layout > activity_main.xml)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layoutManager="android.support.v7.widget.GridLayoutManager"
app:spanCount="2" />
</LinearLayout>
我们应用的主要活动 (MainActivity.kt)
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
import org.json.JSONObject
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setupUi()
}
private fun setupUi() {
// Read file content
val jsonFile = resources
.openRawResource(R.raw.images)
.bufferedReader()
.readText()
// Change "String" in to "Json Object"
val root = JSONObject(jsonFile)
// Get size of the list
val size = root.getString("size").toInt()
// Create (empty) list of people
val peopleList = mutableListOf<Person>()
// Loop to read all of the people
for (position in 0 until size) {
val element = root.getJSONObject(position.toString())
// Change json in to Kotlin object
val photo = Person(
element.getString("image_path"),
element.getString("title")
)
// Add element to the list
peopleList.add(photo)
}
// Add adapter for RecyclerView
recycler_view.adapter = PeopleAdapter(this, peopleList)
}
}
列表元素 (res > layout > list_item.xml)
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/image_view"
android:layout_width="100dp"
android:layout_height="150dp"
android:layout_margin="10dp"
android:scaleType="centerCrop"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/title"
android:layout_width="0dp"
android:layout_height="50dp"
android:background="@color/colorBlack"
android:gravity="center"
android:textColor="@color/colorWhite"
app:layout_constraintBottom_toBottomOf="@id/image_view"
app:layout_constraintEnd_toEndOf="@id/image_view"
app:layout_constraintStart_toStartOf="@id/image_view" />
</android.support.constraint.ConstraintLayout>
表示列表中单个元素的模型类 (Person.kt)
class Person(
val image: String,
val title: String
)
适配器（使用ViewHolder 模式）
import android.content.Context
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.bumptech.glide.Glide
import kotlinx.android.synthetic.main.list_item.view.*
class PeopleAdapter(
private val context: Context,
private val listOfColor: List<Person>
) : RecyclerView.Adapter<PeopleAdapter.ViewHolder>() {
// Creating elements (one item from list)
override fun onCreateViewHolder(viewGroup: ViewGroup, p1: Int): ViewHolder {
val view = LayoutInflater
.from(viewGroup.context)
.inflate(R.layout.list_item, viewGroup, false)
return ViewHolder(view)
}
// Number of elements
override fun getItemCount(): Int = listOfColor.size
// Fill elements with a data
override fun onBindViewHolder(row: ViewHolder, position: Int) {
row.bind(position)
}
// Class responsible for one (single) row
inner class ViewHolder(private val item: View) : RecyclerView.ViewHolder(item) {
fun bind(position: Int) {
// Get image address
val person = listOfColor[position]
// Load image
Glide.with(context).load(person.image).into(item.image_view)
// Set text
item.title.text = person.title
}
}
}
记住大约三 (3) 个依赖项
implementation 'com.android.support:recyclerview-v7:28.0.0'
implementation "com.github.bumptech.glide:glide:4.8.0"
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
和（1）权限（清单）
<uses-permission android:name="android.permission.INTERNET" />
颜色（res > values > colors.xml）
<color name="colorWhite">#FFF</color>
<!-- Black with 50% transparency -->
<color name="colorBlack">#80000000</color>
预期输出：