1、RecyclerView列表布局
在item_view_linear_vertical.xml中:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:orientation="vertical"
android:layout_height="80dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_weight="1"
android:orientation="horizontal"
android:layout_height="0dp">
<ImageView
android:id="@+id/item_image"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_gravity="center_vertical"
android:src="@drawable/ic_launcher_foreground"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:orientation="vertical">
<TextView
android:id="@+id/item_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="地东段减肥标题课程"
android:textColor="#000000"
android:textStyle="bold"
android:singleLine="true"
android:maxLines="10"
android:ellipsize="end"
android:textSize="18dp"/>
<TextView
android:id="@+id/item_message"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="6dp"
android:text="内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容内容呢绒内容"
android:textColor="#666666"
android:textStyle="normal"
android:singleLine="true"
android:ellipsize="end"
android:textSize="14dp"/>
</LinearLayout>
</LinearLayout>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#f3f3f3"/>
</LinearLayout>
在fragment_study.xml中:
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".ui.study.StudyFragment">
<TextView
android:id="@+id/text_home"
android:layout_width="match_parent"
android:layout_height="80dp"
android:gravity="center"
android:background="@color/purple_700"
android:textAlignment="center"
android:textSize="20sp"
android:text="LinerLayoutManager列表布局"
android:textColor="@color/white" />
<!-- 要使用RecyclerView, 首先要确保项目–>app–>build.gradle里面
dependencies {
implementation 'androidx.recyclerview:recyclerview:1.0.2'
...
}
-->
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<!-- <androidx.recyclerview.widget.RecyclerView/>-->
</LinearLayout>
在ui-->study-->StudyFragment中:
package com.dbc.bckotlinall.ui.study
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.dbc.bckotlinall.R
import kotlinx.android.synthetic.main.fragment_study.*
import kotlinx.android.synthetic.main.item_view_linear_vertical.view.*
class StudyFragment: Fragment(R.layout.fragment_study) {//关联布局
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
// 需要先安装扩展插件, 就可以直接通过id名访问控件了
recycler_view.layoutManager = LinearLayoutManager(context,LinearLayoutManager.VERTICAL,false)
recycler_view.adapter = StudyAdapter()
}
// inner 用于声明StudyAdapter是StudyFragment的内部类
inner class StudyAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
val itemView = LayoutInflater.from(context).inflate(R.layout.item_view_linear_vertical, parent, false)
return StudyViewHolder(itemView)
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
/// 在代码中给image控件设置图片的三种方式:
holder.itemView.item_image.setImageResource(R.drawable.ic_dashboard_black_24dp)//✅
holder.itemView.item_image.setImageDrawable(
ContextCompat.getDrawable(
context!!,// !!表示说明此对象不为空
R.drawable.icon_jetpack
)
)
holder.itemView.item_image.setImageBitmap(BitmapFactory.decodeResource(context!!.resource, R.drawable.icon_jetpack))
holder.itemView.item_title.text="标题$position"
holder.itemView.item_message.text="内容${position} 能接收到分离焦虑世纪东方垃圾水电费拉伸点击分类计数法 打开了施法距离卡机士大夫撒的发生撒旦法阿斯顿发安达市 发"
}
override fun getItemCount(): Int {
return 20
}
inner class StudyViewHolder(view: View):RecyclerView.ViewHolder(view){
}
}
}
2、GradLayoutManager网格布局
class HomeFragment : Fragment(R.layout.fragment_home){
override fun onViewCreated(view: View, savedInstanceState: Bundle?){
super.onViewCreated(View, savedInstanceState)
recycler_view.layoutManager = LinearLayoutManager(context, 3)//3表示3列
recycler_view.adapter = MyAdapter()
}
// inner: 声明MyAdapter为HomeFragment的内部类
inner class MyAdapter: RecyclerView.Adapter<MyViewHolder>(){
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyVIewHolder{
//访问外部类的context对象
val itemView = LayoutInflater.from(context)
.inflate(R.layout.item_view_grid, parent, false)
return MyViewHolder(itemView)
}
// 告诉列表有多少条数据
override fun getItemCount(): Int{
return 20
}
//数据绑定
override fun onBindViewHolder(holder: MyViewHolder, position: Int){
/// 在代码中给image控件设置图片的三种方式:
holder.itemView.item_image.setImageResource(R.drawable.icon_jetpack)//✅
holder.itemView.item_image.setImageDrawable(
ContextCompat.getDrawable(
context!!,// !!表示说明此对象不为空
R.drawable.icon_jetpack
)
)
holder.itemView.item_image.setImageBitmap(BitmapFactory.decodeResource(context!!.resource, R.drawable.icon_jetpack))
}
}
class MyViewHolder(view: View): RecyclerView.ViewHolder(view){
}
}
3、StaggeredGridLayoutManager瀑布流
recycleView.adapter = MyAdapter()
class HomeFragment : Fragment(R.layout.fragment_home){
override fun onViewCreated(view: View, savedInstanceState: Bundle?){
super.onViewCreated(View, savedInstanceState)
recycler_view.layoutManager = StaggeredGridLayoutMananger(2, StaggeredGridLayoutMananger.VERTICAL)//2表示2列, VERTICAL表示纵向瀑布流
recycler_view.adapter = MyAdapter()
}
// inner: 声明MyAdapter为HomeFragment的内部类
inner class MyAdapter: RecyclerView.Adapter<MyViewHolder>(){
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyVIewHolder{
//访问外部类的context对象
val itemView = LayoutInflater.from(context)
.inflate(R.layout.item_view_grid, parent, false)
return MyViewHolder(itemView)
}
// 告诉列表有多少条数据
override fun getItemCount(): Int{
return 20
}
//数据绑定
override fun onBindViewHolder(holder: MyViewHolder, position: Int){
/// 在代码中给image控件设置图片的三种方式:
holder.itemView.item_image.setImageResource(R.drawable.icon_jetpack)//✅
if(position == 0||position == 3||position == 4||position == 7||position == 9){
holder.itemView.item_message.setSingleLine(false)//取消设置单行显示
} else {
holder.itemView.item_message.setSingleLine(true)//单行显示
}
holder.itemView.item_message.text = "xxxxx"
}
}
class MyViewHolder(view: View): RecyclerView.ViewHolder(view){
}
}
4、快速实现圆角阴影的组件
// 这一行代码, 放在顶部layout标签中声明
xmlns:app="http://schemas.android.com/apk/res-auto"
<androidx.cardview.widget.CardView
android: layout_width = "match_parent"
app:cardBackgroundColor="@color/white"//设置背景色
app:CardCornerRadius="10dp"//设置圆角
Android: layout_marginLeft="16dp"
Android: layout_marginRight="16dp"
android: layout_height="140dp">
<LinerLayout
android:layout_width="match_parent"
androdi:layout_height="match_parent"
android:orientation="horizontal">
<com.google.android.material.button.MaterialButton
android:id="@+id/item_collect"
android: layout_width="0dp"
style="@style/Widget.MaterialComponents.Button.UnelevatedButton"//去除按钮默认描边阴影效果
androdi:layout_height="match_parent"
android:layout_weight="1"
android:backgroundTint="@color/white"
android:text="收藏"
app:icon="@drawable/main_component_my_course_collect"
app:iconGravity="textTop"//icon位于文字的上方
app:iconSize="25dp"
app:iconTint="@null"//icon默认颜色为白色, 设置为空显示原有颜色
android:padding="0dp"//去除默认内间距
android:insetTop="0dp"//去除默认留白
android:insetBottom="0dp"//去除默认留白
android:textColor="#333333"/>
...
</LinerLayout>
</androidx.cardview.widget.CardView>
AndroidStudio配置阿里云镜像 2021.02.25 10:46 2020浏览
https://www.imooc.com/article/315290
Mac IDEA配置阿里云国内镜像 发布于 2020-07-30
https://segmentfault.com/a/1190000023086534
警告:You have JVM property “https.proxyHost“ set to “127.0.0.1“
https://www.jianshu.com/p/9cec82d9498e
5、网络请求框架OKHTTP--GET请求
在app->manifests->AndroidManifest.xml添加网络访问权限:
<!-- 请求权限-->
<uses-permission android:name="android.permission.INTERNET" />
<!-- 写入权限-->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<!-- 读取权限-->
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
...
android:usesCleartextTraffic="true" //允许发起Http请求
....>
</application>
在app/build.gradle的dependencies中添加下面的依赖
dependencies {
...
implementation("com.squareup.okhttp3:okhttp:4.9.0")
// 网络请求日志打印
implementation("com.squareup.okhttp3:logging-interceptor:4.9.0")
}
在http->HiOkHttp中
package com.dbc.bckotlinall.http
import android.util.Log
import okhttp3.Call
import okhttp3.OkHttpClient
import okhttp3.Request
import java.util.concurrent.TimeUnit
// 使用class需要创建实例对象
// 使用object的声明方式, 就没有必要构建它的实例对象了, 直接可以类.方法调用
object HiOkHttp {
private val BASE_URL="http://123.56.232.18:8080/serverdemo"
//全局中只有一份
val client = OkHttpClient.Builder() //builder构造者设计模式
.connectTimeout(10, TimeUnit.SECONDS) //连接超时时间
.readTimeout(10, TimeUnit.SECONDS) //读取超时
.writeTimeout(10, TimeUnit.SECONDS) //写超时，也就是请求超时
.build();
// Android分为主线程和子线程
// 主线程就是APP一启动后, Android framework层会启动一个线程, 主线程(UI线程)
// 子线程 -- 可以通过new Thread().start()创建
//方式一: 同步GET请求
fun get(url: String) {//网络请求接口
Thread(Runnable {//开启子线程
//构造请求体
val request: Request = Request.Builder()
// .url(url)
.url("$BASE_URL/user/query?userId=1600932269")
.build()
//构造请求对象
val call: Call = client.newCall(request)
// 通过.execute()发起同步请求--同步执行
val response = call.execute()
val body = response.body?.string()
// println("get response :${body}")
Log.e("OKHTTP","get response :${body}")
}).start()
}
//方式二: 异步GET请求
fun getAsync(url: String) {//网络请求接口
//构造请求体
val request: Request = Request.Builder()
// .url(url)
.url("$BASE_URL/user/query?userId=1600932269")
.build()
//构造请求对象
val call: Call = client.newCall(request)
// 通过.enqueue()发起异步请求--异步执行
call.enqueue(object: Callback {//异步请求没有返回值
override fun onFailure(call: Call, e: IOException) {
Log.e("OKHTTP","失败原因 :${e}")
}
override fun onResponse(call: Call, response: Response) {
val body = response.body?.string()
Log.e("OKHTTP","get response :${body}")
}
})
}
}
在MainActivity.kt中使用:
HiOkHttp.get()
6、网络请求框架OKHTTP--POST请求
http://123.56.232.18:8080/serverdemo/swagger-ui.html#/tag-list-controller/toggleTagFollowUsingPOST
/// 同步表达提交
fun post(){
val body = FormBody.Builder()
.add("userId","1600932269")
.add("tagId","71")
.build()
val request = Request.Builder().url("$BASE_URL/tag/toggleTagFollow")
.post(body)
.build()
val call = client.newCall(request)
Thread(Runnable {
val response = call.execute()
Log.e("OKHTTP","post response: ${response.body?.string()}")
}).start()
}
/// 异步表单提交
fun postAsync(){
val body = FormBody.Builder()
.add("userId","1600932269")
.add("tagId","71")
.build()
val request = Request.Builder().url("$BASE_URL/tag/toggleTagFollow")
.post(body)
.build()
val call = client.newCall(request)
call.enqueue(object :Callback{
override fun onFailure(call: Call, e: IOException) {
Log.e("OKHTTP","失败原因 :${e}")
}
override fun onResponse(call: Call, response: Response) {
val body = response.body?.string()
Log.e("OKHTTP","post response :${body}")
}
})
}
/// 异步多表单文件上传, 在Android6.0以后, 读取外部存储卡文件都是需要动态申请权限的
fun postAsyncMultipart(context: Context) {
val file = File(Environment.getExternalStorageDirectory(), "1.png")// 文件目录, 文件名称
if (!file.exists()) {
Toast.makeText(context, "文件不存在", Toast.LENGTH_SHORT).show()
return
}
val body = MultipartBody.Builder()
.addFormDataPart("key","value")
.addFormDataPart("key1","value1")
.addFormDataPart(
"file",
"1.png",
RequestBody.create("application/octet-stream".toMediaType(), file)
)
.build()
val request = Request.Builder().url("接口是需要支持文件上传才可以使用的")
.post(body)
.build()
val call = client.newCall(request)
call.enqueue( object : Callback{
override fun onFailure(call: Call, e: IOException) {
Log.e("OKHTTP","失败原因 :${e}")
}
override fun onResponse(call: Call, response: Response) {
val body = response.body?.string()
Log.e("OKHTTP","postAsyncMultipart response :${body}")
}
})
}
/// 异步POST请求---提交字符串
fun postString(){
///可以是JSON字符串, 也可以是纯文本字符串
//纯文本
// val textPlain = "text/plain;charset=utf-8".toMediaType()
// val textObj = "{username:admin, password:admin}"
// val body = RequestBody.create(textPlain,textObj)
//Json字符串
val jsonObj = JSONObject()
jsonObj.put("key1","value1")
jsonObj.put("key2",100)
val applicationJson = "application/json;charset=utf-8".toMediaType()
val body = RequestBody.create(applicationJson,jsonObj.toString())
val request = Request.Builder().url("$BASE_URL")
.post(body)
.build()
val call = client.newCall(request)
call.enqueue( object : Callback{
override fun onFailure(call: Call, e: IOException) {
Log.e("OKHTTP","失败原因 :${e}")
}
override fun onResponse(call: Call, response: Response) {
val body = response.body?.string()
Log.e("OKHTTP","postString response :${body}")
}
})
}
7、拦截器LoggingInterceptor
使用OkHttp默认拦截器
object HiOkHttp {
private val BASE_URL="http://123.56.232.18:8080/serverdemo"
private val client: OkHttpClient
init {
val httpLoggingInterceptor = HttpLoggingInterceptor()
httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY)
client = OkHttpClient.Builder() //builder构造者设计模式
.connectTimeout(10, TimeUnit.SECONDS) //连接超时时间
.readTimeout(10, TimeUnit.SECONDS) //读取超时
.writeTimeout(10, TimeUnit.SECONDS) //写超时，也就是请求超时
.addInterceptor(httpLoggingInterceptor)//使用默认拦截器
.build();
}
....
}
使用自定义拦截器:
/// ①在LoggingInterceptor.kt中:
package com.dbc.bckotlinall.http
import android.util.Log
import okhttp3.Interceptor
import okhttp3.Response
import okhttp3.ResponseBody
import okio.Buffer
/// 拦截器要做的事: 打印拦截请求时的接口、携带哪些参数
class LoggingInterceptor: Interceptor {
override fun intercept(chain: Interceptor.Chain): Response {
val time_start = System.nanoTime()
val request = chain.request() //获取request对象
val response = chain.proceed(request)//获取response对象
val buffer = Buffer()
request.body?.writeTo(buffer)
val requestBodyStr = buffer.readUtf8()//把request.body转换成字符串
//打印请求前的: 地址 和 请求参数
Log.e("OKHTTP",String.format("Sending request %s with params %s",request.url, requestBodyStr))
val bussinessData = response.body?.string()?:"response body null" //读取输出流,获取接口返回的数据
/*由于OKHTTP的工作原理: 一旦调用了response.body?.string()方法, 今后再也不能用response去读取它的响应流了.
*
* 这也就意味着: onResponse回调函数中,再次读取response.body?.string()就会报错. 这是OKHTTP的工作原理决定的.
*
* 对于Response响应流只能读取一次的解决办法是: 返回一个新的Response.
* */
val mediaType = response.body?.contentType()
val newBody = ResponseBody.create(mediaType, bussinessData)
val newResponse = response.newBuilder().body(newBody).build()
val time_end = System.nanoTime()
//打印请求后的结果
Log.e("OKHTTP", String.format("Received response for %s in %.1fms >>> %s", request.url,(time_end-time_start)/1e6,bussinessData))
return newResponse
}
}
///②在HiOkHttp中使用:
object HiOkHttp {
private val BASE_URL="http://123.56.232.18:8080/serverdemo"
val client = OkHttpClient.Builder()
.connectTimeout(10, TimeUnit.SECONDS)
.readTimeout(10, TimeUnit.SECONDS)
.writeTimeout(10, TimeUnit.SECONDS)
.addInterceptor(LoggingInterceptor()) //添加自定义拦截器
.build();
...
}
8、使用Gson来解析网络请求响应
在app/build.gradle中添加以下依赖配置
dependencies {
implementation 'com.google.code.gson:gson:2.8.6'
}
在Account.kt中使用:
package com.dbc.bckotlinall.ui.study
import com.google.gson.Gson
import com.google.gson.reflect.TypeToken
fun main() {
/// 把JSON转换成对象
val json ="{\"uid\":\"00001\",\"userName\":\"Freeman\",\"telNumber\":\"13000000000\"}"
val gson = Gson()//构建gson对象
// 在kotlin中传入class类型, 需要xxx::class.java 格式
val account:Account = gson.fromJson<Account>(json, Account::class.java)
println("fromJson: ${account.toString()}")
/// 把对象转换成JSON
val accountJson = gson.toJson(account)
println("toJson: ${accountJson}")
/// 将JSON转换成集合
val jsonList= "[{\"uid\":\"00001\",\"userName\":\"Freeman\",\"telNumber\":\"13000000000\"}]"
val accountList: List<Account> = gson.fromJson(jsonList, object:TypeToken<List<Account>>(){}.type)
println("fromJson to List:${accountList.size}")
/// 将集合转化成JSON
val accountJsonList = gson.toJson(accountList)
println("list to json: ${accountJsonList}")
}
class Account {
/// 在kotlin中必须指定初始值
var uid:String=""
var userName:String=""
var password:String=""
var telNumber:String=""
//✅快速生成toString: 首先选中这几个字段-->右键"Generate"-->选择"toString()"-->全选
override fun toString(): String {
return "Account(uid='$uid', userName='$userName', password='$password', telNumber='$telNumber')"
}
}
如果对象模型使用data class, 就可以不用指定初始值了:
data class Account(
var uid:String = "111",
var userName:String,
var password:String,
var telNumber:String
)
使用插件快速生成复杂的数据模型 -- JsonToKotlin插件:
sp1.在网站 https://github.com/wuseal/JsonToKotlinClass/releases/ 下载最新版本zip包
sp2.在AS-->Preferences-->Plugins-->点击"设置"按钮, 选择"install Plugin from Disk..."--->选择下载的包,点击"OK", 重启IDE
使用插件:
在空白的地方, 右键选择"Generate"-->选择"Kotlin data classes from JSON"-->将JSON字符串拷贝到这里-->点击"Format", 输入"Class Name: xxx", 选择"Generate" --> 就生成了xxx对象模型
val userModelJson = "{ ... }"
val userResponse:UserResponse! = gson.fromJson<UserResponse>(userModelJson, UserResponse::class.java)
println("userResponse: $userResponse")
9、RESTFUL网络请求框架Retrofit
retrofit注解驱动型上层网络请求框架, 使用注解来简化请求, 大体分为以下几类:
- 用于标注网络请求的注解
- 标记网络请求参数的注解
- 用于标记网络请求和响应格式的注解
添加依赖:
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0' //json转换
在HiRetrofit.kt中, 封装Retrofit&定义接口:
package com.dbc.bckotlinall.http
import okhttp3.OkHttpClient
import retrofit2.Call
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import retrofit2.http.GET
import retrofit2.http.Query
import java.util.concurrent.TimeUnit
object HiRetrofit {
// https://www.cnblogs.com/hanma/p/14942740.html
private val client = OkHttpClient.Builder() //builder构造者设计模式
.connectTimeout(10, TimeUnit.SECONDS) //连接超时时间
.readTimeout(10, TimeUnit.SECONDS) //读取超时
.writeTimeout(10, TimeUnit.SECONDS) //写超时，也就是请求超时
.addInterceptor(LoggingInterceptor())
.build();
private val retrofit = Retrofit.Builder()
.client(client)//配置OKHTTP网络请求的一个对象
.baseUrl("http://123.56.232.18:8080/serverdemo/")//配置网络请求的域名
.addConverterFactory(GsonConverterFactory.create())//数据转换器: 自动转换成数据模型
.build();
///定义一个泛型方法
fun <T> create(clazz: Class<T>): T {
return retrofit.create(clazz)
}
}
/// 定义一个接口文件, 编写网络请求方法
interface APIService{
@GET(value="user/query")
fun queryUser(@Query(value="userId",encoded = true) userId: String):Call<UserResponse>
//UserResponse: 要转换的数据模型对象类
}
在MainActivity.kt中使用:
val apiService = HiRetrofit.create(APIService::class.java)
// 此时onFailure 和 onResponse的回调都是在主线程的; 但OKHTTP的回调是在子线程的,如果UI操作还需要回到主线程.
apiService.queryUser("1600932269").enqueue(object: Callback<UserResponse>{
override fun onFailure(call: Call<UserResponse>, t: Throwable) {
Log.e("Retrofit","失败原因 :${t.message}")
}
override fun onResponse(call: Call<UserResponse>, response: Response<UserResponse>) {
val body = response.body?.string()
Log.e("Retrofit","get response :${body}")
}
})
10、网络图片的加载
在app/build.gradle中添加以下配置。使用Glide加载图片
plugins {
...
id 'kotlin-kapt'
}
dependencies {
...
implementation 'com.github.bumptech.glide:glide:4.9.0'
kapt 'com.github.bumptech.glide:compiler:4.9.0'
}
11、数据请求与绑定
class StudyFragment: Fragment(R.layout.fragment_study) {//关联布局
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val adapter = StudyAdapter()
recycler_view.layoutManager = LinearLayoutManager(context,LinearLayoutManager.VERTICAL,false)
recycler_view.adapter = adapter
HiRetrofit.create(ApiService::class.java)
.getStudy().enqueue(object: CallBack<List<Course>>{
override fun onFailure(call: Call<List<Course>>, t: Throwable){
Log.e("onFailure:", t.message ?: "unknown error")
}
override fun onResponse(
call: Call<List<Course>>,
response: Response<List<Course>>
){
Log.e("onResponse:", response.body()?.toString() ?: "unknown error")
response.body()?.let{
adapter.setDatas(it)//更新UI
}
}
})
}
inner class StudyAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
private val courses = mutableListOf<Course>()
fun setDatas(datas: List<Course>) {
if (datas.isNotEmpty()){
courses.addAll(datas)
notifyDataSetChanged() //这个命令会重新执行getItemCount和onBindViewHolder
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
val itemView = LayoutInflater.from(context).inflate(R.layout.item_view_linear_vertical, parent, false)
return StudyViewHolder(itemView)
}
// 重写执行这里才会刷新
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
val course = courses[position]
// holder.itemView.item_image.setImageResource(R.drawable.ic_dashboard_black_24dp)//本地图片
//设置圆角
val options = RequestOptions()
.transform(RoundedCorners(10))//设置圆角
//添加网络图片
Glide.with(context!!)
.load(course.poster)//设置图片地址
.apply ( options )
.into(holder.itemView.item_course_poster)//绑定控件
holder.itemView.item_title.text = course.title
holder.itemView.item_message.text="内容${position} "
}
override fun getItemCount(): Int {
return courses.size
}
inner class StudyViewHolder(view: View):RecyclerView.ViewHolder(view){
}
}
}
12、列表的增删改查
class StudyFragment: Fragment(R.layout.fragment_study) {//关联布局
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val adapter = StudyAdapter()
recycler_view.layoutManager = LinearLayoutManager(context,LinearLayoutManager.VERTICAL,false)
recycler_view.adapter = adapter
//点击增加按钮
tab_add_course.setOnClickListener{
val course = Course(
label = "Android学习基础",
poster = "https://www.songyubao.com/static/book/assets/icon-android.jpeg",
progress = "100%",
title = "Android RecyclerView基础学习"
)
adapter.addCourse(course)
recycler_view.scrollToPosition(0)//滑动到第0个位置
}
//点击删除按钮
tab_delete_course.setOnClickListener{
adapter.deleteCourse(0)
}
//点击更新按钮
tab_update_course.setOnClickListener{
adapter.updateCourse(0, "80%")
}
...
}
inner class StudyAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
private val courses = mutableListOf<Course>()
fun setDatas(datas: List<Course>) {
if (datas.isNotEmpty()){
courses.addAll(datas)
notifyDataSetChanged() //这个命令会重新执行getItemCount和onBindViewHolder
}
}
fun addCourse(course: Course){
// courses.add(0, course)
// notifyItemChanged(0)
courses.add(course)
//notifyDataSetChanged()//更新整个列表
notifyItemChanged(courses.size - 1)
}
fun deleteCourse(position: Int){
courses.removeAt(position)
//notifyDataSetChanged()//更新整个列表
notifyItemRemoved(position)
}
fun updateCourse(position: Int, progress:String){
val course = courses[position]
course.progress = progress
//notifyDataSetChanged()//更新整个列表
notifyItemChanged(position)
}
...
AS操作小技巧
- 查看Kotlin编译之后的字节码, 有助于我们深入理解kotlin语言, 有两种方式:
- Shift键两次, 输入Show kotlin
- Tools->Kotlin->Show Kotlin Bytecode
