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kotlin学习日志4 - 在android中的应用

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kotlin在AndroidStudio的环境配置

java代码转化kotlin

AndroidStudio中，help->FindAction->Convert Java File to Kotlin File
如果快捷键是android studio默认的(ctrl+shift+A)

可视化操作

  1. android studio中，Tools->Kotlin->Configure kotlin in project->Android with Gradle
  2. 选择所有模块配置还是单模块配置
  3. 选择kotlin版本号

    直接修改代码

  4. 修改项目根目录下的build.gradle文件
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    buildscript {
        ext.kotlin_version = '1.1.2-5'
        ext.anko_version= '0.8.2'
        repositories {
            jcenter()
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:2.3.3'
            classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
            classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
            // NOTE: Do not place your application dependencies here; they belong
            // in the individual module build.gradle files
        }
    }

    allprojects {
        repositories {
            jcenter()
        }
    }


    repositories {
        mavenCentral()
    }
  5. 修改app下的build.gradle文件
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    apply plugin: 'com.android.application'
    apply plugin: 'kotlin-android'
    apply plugin: 'kotlin-android-extensions'

    android {
        compileSdkVersion 25
        buildToolsVersion "25.0.3"
        defaultConfig {
            applicationId "kotlinstudy.jessie.com.kotlinstudy"
            minSdkVersion 15
            targetSdkVersion 25
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

        }



        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            }
        }
        compileOptions {
            sourceCompatibility JavaVersion.VERSION_1_7
            targetCompatibility JavaVersion.VERSION_1_7
        }
    }

    dependencies {
        compile fileTree(include: ['*.jar'], dir: 'libs')
        androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
            exclude group: 'com.android.support', module: 'support-annotations'
        })
        compile 'com.android.support:appcompat-v7:25.3.1'
        compile 'com.android.support.constraint:constraint-layout:1.0.2'
        testCompile 'junit:junit:4.12'
        compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
        compile "org.jetbrains.anko:anko-common:$anko_version"
    }

    findViewById

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    val forecastList: RecyclerView = find(R.id.forecast_list)

    activity的跳转

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    startActivity<DetailActivity>(DetailActivity.ID to it.id,
                      DetailActivity.CITY_NAME to weekForecast.city)

数据类的封装

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data class ForecastList(val id: Long, val city: String, val country: String,
        val dailyForecast: List<Forecast>) {

    val size: Int
        get() = dailyForecast.size

    operator fun get(position: Int) = dailyForecast[position]
}

data class Forecast(val id: Long, val date: Long, val description: String, val high: Int,val low: Int,val iconUrl: String)

扩展函数

dp与px的转换

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fun Int.dpToPx(): Int {
    if (toInt() in intArrayOf(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT)) 	 {
        return this
    }
    return (this * Global.density).toInt() //这里的Gloabl.density是在应用启动时获取的
}
//params.topMargin = 16.dpTpPx()

设置view的宽高

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fun View.setSize(width: Int, height: Int) {
    val params = layoutParams
    params.width = width
    params.height = height
    layoutParams = params
}
//yourView.setSize(100, 100)

设置imageview的图片加载

使用glide做图片加载

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object GlideUtils {
    /*
        当fragment或者activity失去焦点或者destroyed的时候，Glide会自动停止加载相关资源，确保资源不会被浪费
     */
    fun loadUrlImage(context: Context, url: String, imageView: ImageView){
        get(context, url).placeholder(R.drawable.icon_back).error(R.drawable.icon_back).centerCrop().into(
                object : SimpleTarget<GlideDrawable>() {
                    override fun onResourceReady(resource: GlideDrawable,
                                                 glideAnimation: GlideAnimation<in GlideDrawable>) {
                        imageView.setImageDrawable(resource)
                    }
                })
    }

    /**
     * 加载圆形图片
     */
    fun loadCircleImage(context: Context,url: String,imageView: ImageView){
        get(context, url)
                .asBitmap()  //这句不能少，否则下面的方法会报错
                .centerCrop()
                .into(object :BitmapImageViewTarget(imageView){
                    override fun setResource(resource: Bitmap?) {
                        super.setResource(resource)
                        var circularBitmapDrawable = RoundedBitmapDrawableFactory.create(context.resources, resource)
                        circularBitmapDrawable.isCircular=true
                        imageView.setImageDrawable(circularBitmapDrawable)

                    }
                } )
    }

    fun loadRoundImage(context: Context,url: String,size:Int,imageView: ImageView){
        get(context, url)
                .transform(CenterCrop(context),GlideRoundTransform(context, size))
                .into(imageView)
    }

    fun get(context: Context, url: String): DrawableTypeRequest<String> =  Glide.with(context).load(url)
}


fun ImageView.loadUrl(url: String) {
    GlideUtils.loadUrlImage(context, url, this)
}

内联函数关闭io流

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inline fun <T : Closeable?> T.use(block: (T) -> Unit) {
       var closed = false
       try {
           block(this)
       } catch (e: Exception) {
           closed = true
           try {
               this?.close()
           } catch (closeException: Exception) {
           }
           throw e
       } finally {
           if (!closed) {
               this?.close()
           }
       }
   }
 // 使用
fun testIo(bitmap: Bitmap) {
       val file = File("/pic/")
       val fileOutputStream: FileOutputStream? = FileOutputStream(file)
       fileOutputStream.use { t ->
           bitmap.compress(Bitmap.CompressFormat.PNG, 100, t)
       }
}

with函数块

with函数块,用对象作为函数的参数,内部通过 this 指代该对象,直接调用对象的方法或者属性
典型用法,在onBindViewHolder中捆绑数据

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 with(model){
     //是否选中
     holder.itemView.checkedCb.isChecked = isSelected
     //加载商品图片
     holder.itemView.goodsIconIv.loadUrl(goodsIcon)
     //商品描述
     holder.itemView.goodsDescTv.text = goodsDesc
     //商品SKU
     holder.itemView.goodsSkuTv.text = goodsSku
}

kotlin代码埋点

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fun <T : View> T.clickWithTrack(eventName: String, time: Long = 600, block: (T) -> Unit) = this.clickWithTrigger(time) {
    TrackAgent.currentEvent().customEvent(eventName)//自定义埋点逻辑
    block(it as T) //正常逻辑
}

fun <T : View> T.clickWithTrack(eventName: String, trackMap: HashMap<String, String>, time: Long = 600, block: (T) -> Unit) = this.clickWithTrigger(time) {
    TrackAgent.currentEvent().customEvent(eventName, trackMap)//自定义埋点逻辑
    block(it as T)//正常逻辑
}
// 使用
view.clickWithTrack(key) {}
view.clickWithTrack(key,trackMap) {}

重复点击过滤

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/***
 * 设置有效点击时间范围和点击事件
 * @param delay Long 有效点击时间，默认600毫秒后
 */
fun <T : View> T.clickWithTrigger(time: Long = 600, block: (T) -> Unit){
    triggerDelay = time
    setOnClickListener {
        if (clickEnable()) {
            block(it as T)
        }
    }
}

/*
* 最后一次点击时间属性扩展
*/
private var <T : View> T.triggerLastTime: Long
    // 从tag取出
    get() = if (getTag(1123460103) != null) getTag(1123460103) as Long else 0
    // 保存到tag
    set(value) {
        setTag(1123460103, value)
    }

/*
* 有效点击时间属性扩展
*/
private var <T : View> T.triggerDelay: Long
    // 从tag取出
    get() = if (getTag(1123461123) != null) getTag(1123461123) as Long else -1
    // 保存到tag
    set(value) {
        setTag(1123461123, value)
    }

/**
* 点击是否有效判断
*/
private fun <T : View> T.clickEnable(): Boolean {
    var flag = false
    val currentClickTime = System.currentTimeMillis()
    if (currentClickTime - triggerLastTime >= triggerDelay) {
        flag = true
    }
    triggerLastTime = currentClickTime
    return flag
}

// 使用
view.clickWithTrigger(700) {}

sharedPreferences封装

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class Preference<T>(val context: Context, val name: String?, val default: T) : ReadWriteProperty<Any?, T> {
    val prefs by lazy {
        context.getSharedPreferences("xxxx", Context.MODE_PRIVATE)
    }

    override fun getValue(thisRef: Any?, property: KProperty<*>): T = with(prefs) {
        val res: Any = when (default) {
            is Long -> {
                getLong(name, 0)
            }
            is String -> {
                getString(name, default)
            }
            is Float -> {
                getFloat(name, default)
            }
            is Int -> {
                getInt(name, default)
            }
            is Boolean -> {
                getBoolean(name, default)
            }
            else -> {
                throw IllegalArgumentException("This type can't be saved into Preferences")
            }
        }
        res as T
    }

    override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) = with(prefs.edit()) {
        when (value) {
            is Long -> putLong(name, value)
            is String -> putString(name, value)
            is Float -> putFloat(name, value)
            is Int -> putInt(name, value)
            is Boolean -> putBoolean(name, value)
            else -> {
                throw IllegalArgumentException("This type can't be saved into Preferences")
            }
        }.apply()
    }
}

//调用例子
class EntranceActivity : BaseActivity() {

    private var userId: String by Preference(this, "userId", "")

    override fun onCreate(savedInstanceState: Bundle?) {
        testUserId()
    }

    fun testUserId() {
        if (userId.isEmpty()) {
            println("userId is empty")
            userId = "default userId"
        } else {
            println("userId is $userId")
        }
    }
}

getExtra封装

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class ExtrasDelegate <out T>(private val extraName: String, private val defaultValue: T){
    private var extra: T? = null

    // 适配AppCompatActivity
    operator fun getValue(thisRef: AppCompatActivity, property: KProperty<*>): T {
        extra = getExtra(extra, extraName, thisRef)
        return extra ?: defaultValue
    }

    // 适配Fragment
    operator fun getValue(thisRef: Fragment, property: KProperty<*>): T {
        extra = getExtra(extra, extraName, thisRef)
        return extra ?: defaultValue
    }
}

// 调用委托类
fun <T> extraDelegate(extra: String, default: T) = ExtrasDelegate(extra, default)

// 委托调用入口
fun extraDelegate(extra: String) = extraDelegate(extra, null)

// 根据key取值,适配AppCompatActivity
@Suppress("UNCHECKED_CAST")
private fun <T> getExtra(oldExtra: T?, extraName: String, thisRef: AppCompatActivity): T? =
        oldExtra ?: thisRef.intent?.extras?.get(extraName) as T?

// 根据key取值,适配Fragment
@Suppress("UNCHECKED_CAST")
private fun <T> getExtra(oldExtra: T?, extraName: String, thisRef: Fragment): T? =
        oldExtra ?: thisRef.arguments?.get(extraName) as T?

// 调用例子
startActivity<GoodsDetailActivity>(GoodsConstant.KEY_GOODS_ID to item.id)
class GoodsDetailActivity : BaseActivity() {
private val goodsId: Int? by extraDelegate(GoodsConstant.KEY_GOODS_ID)
}
    override fun onCreate(savedInstanceState: Bundle?) {
        testGoodsId()
    }

    fun testGoodsId() {
        if (goodsId.isEmpty()) {
            println("goodsId is empty")
            userId = "default goodsId"
        } else {
            println("goodsId is $goodsId")
        }
    }

Application 的单例

使用not null 委托模式

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class App : Application() {
    companion object {
        var instance: App by Delegates.notNull()
    }

    override fun onCreate() {
            super.onCreate()
            instance = this
    }
}

recyclerview的使用

初始化recyclerview,设置layoutManager和adapter

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lateinit var mAdapter: MyAdapter
recyclerView.layoutManager = LinearLayoutManager(context)
mAdapter = MyAdapter(context, mList,{ data: DataBean -> Toast.makeText(activity,data.type, Toast.LENGTH_SHORT).show()})
recyclerView.adapter = mAdapter

自定义adapter

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class MyAdapter(context: Context, list: ArrayList<DataBean>, val itemClick: (DataBean) -> Unit) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
    var context: Context? = null;
    var list: ArrayList<DataBean>? = null
    var inflater: LayoutInflater? = null

    init {
        this.context = context
        this.list = list
        this.inflater = LayoutInflater.from(context)
    }

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): MyViewHolder {
        return MyViewHolder(inflater?.inflate(R.layout.item_rank, parent, false), context!!,itemClick)
    }

    override fun getItemCount(): Int {
        return list?.size ?: 0
    }

    override fun onBindViewHolder(holder: MyViewHolder?, position: Int) {
        var photoUrl : String? = list?.get(position)?.cover?.feed
        photoUrl?.let { ImageLoadUtils.display(context!!,holder?.iv_photo, it) }
        var title : String? = list?.get(position)?.title
        holder?.tv_title?.text = title
        var category = list?.get(position)?.category
        var duration = list?.get(position)?.duration
        var minute =duration?.div(60)
        var second = duration?.minus((minute?.times(60)) as Long )
        var realMinute : String
        var realSecond : String
        if(minute!!<10){
            realMinute = "0"+minute
        }else{
            realMinute = minute.toString()
        }
        if(second!!<10){
            realSecond = "0"+second
        }else{
            realSecond = second.toString()
        }
        holder?.tv_time?.text = "$category / $realMinute'$realSecond''"
        holder?.itemView?.setOnClickListener {
            //跳转视频详情页
            var intent : Intent = Intent(context, VideoDetailActivity::class.java)
            var desc = list?.get(position)?.description
            var playUrl = list?.get(position)?.playUrl
            var blurred = list?.get(position)?.cover?.blurred
            var collect = list?.get(position)?.consumption?.collectionCount
            var share = list?.get(position)?.consumption?.shareCount
            var reply = list?.get(position)?.consumption?.replyCount
            var time = System.currentTimeMillis()
            var videoBean  = VideoBean(photoUrl,title,desc,duration,playUrl,category,blurred,collect ,share ,reply,time)
            var url = SPUtils.getInstance(context!!,"beans").getString(playUrl!!)
            if(url.equals("")){
                var count = SPUtils.getInstance(context!!,"beans").getInt("count")
                if(count!=-1){
                    count = count.inc()
                }else{
                    count = 1
                }
                SPUtils.getInstance(context!!,"beans").put("count",count)
                SPUtils.getInstance(context!!,"beans").put(playUrl!!,playUrl)
                ObjectSaveUtils.saveObject(context!!,"bean$count",videoBean)
            }
            intent.putExtra("data",videoBean as Parcelable)
            context?.let { context -> context.startActivity(intent) }
        }
    }


    inner class MyViewHolder(itemView: View?, context: Context, val itemClick: (DataBean) -> Unit) : RecyclerView.ViewHolder(itemView) {
        var iv_photo: ImageView = itemView?.findViewById(R.id.iv_photo) as ImageView
        var tv_title: TextView = itemView?.findViewById(R.id.tv_title) as TextView
        var tv_time: TextView = itemView?.findViewById(R.id.tv_time) as TextView
        init {
            tv_title?.typeface = Typeface.createFromAsset(context?.assets, "fonts/FZLanTingHeiS-L-GB-Regular.TTF")
        bind()
        }
      fun bind() {
            itemView.setOnClickListener {
                itemClick(list?.get(layoutPosition) as DataBean)
            }
        }
    }
}

封装操作符

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// 自定义Run方法
fun <T,R> T.myRun(m:() -> R): R{
    return m()
}
common().myRun{
    println("A")
}
fun <T> T.myRunOk(mm:() -> Boolean){
    mm()
}
common().myRunOk{
    true
}
// 自定义with方法
fun<T,R> myWith(input:T, mm:T.() -> R):R {
    return input.mm()
}
myWith("123"){length}
// 自定义let方法
fun <T,R> T.myLet(mm: (T) -> R):R {
    return mm(this)
}
"123".myLet {print(it)}

封装线程

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// 封装线程
fun ktRun(start: Boolean = true, name: String ? = null, myRunAction: () -> Unit): Thread {
    val thread = object: Thread(){
        override fun run(){
            super.run()
            myRunAction()
        }
    }

    name ?: "MyThread"
    if (start){
        thread.start()
    }
    return thread
}

ktRun{}

封装循环

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// 封装循环
fun countLoop(count: Int,myFun: (Int) -> Unit){
    for (i in 0 .. count){
        myFun(i)
    }
}
countLoop(4){}