【40】kotlin 協程異步下載圖片3

改爲異步新建async包

新建AsyncTask.kt

package com.yzdzy.kotlin.chapter7.async

import java.util.concurrent.Executors

//線程池
private val pool by lazy {
    Executors.newCachedThreadPool()
}
class AsyncTask(val block: () -> Unit) {
    fun execute() = pool.execute(block)
}

修改BaseCoroutines.kt

package com.yzdzy.kotlin.chapter7.basic

import cn.kotliner.coroutine.common.HttpError
import cn.kotliner.coroutine.common.HttpException
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import cn.kotliner.coroutine.ui.LOGO_URL
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import java.lang.Exception
import javax.xml.ws.http.HTTPException
import kotlin.coroutines.resume
import kotlin.coroutines.resumeWithException
import kotlin.coroutines.startCoroutine
import kotlin.coroutines.suspendCoroutine

fun 我要開始協程了(block: suspend () -> Unit) {
    block.startCoroutine(BaseCoroutines())
}

suspend fun 我要開始加載圖片了(url: String) = suspendCoroutine<ByteArray> { continuation ->

    AsyncTask {

        log("耗時下載圖片")
        try {
            val reponseBody = HttpService.service.getLogo(LOGO_URL).execute()
            if (reponseBody.isSuccessful) {
                reponseBody.body()?.byteStream()?.readBytes()?.let(continuation::resume)
            } else {
                continuation.resumeWithException(HttpException(reponseBody.code()))
            }
        } catch (e: Exception) {
            continuation.resumeWithException(e)
        }
    }.execute()
}

運行看log

異步已經完成了。

但是main setLogo應該在主線程執行。而不是子線程。。如何操作呢

繼續修改BaseCoroutines.kt 下面的第一段代碼是講如何切換到ui線程第二段是整個BaseCoroutines.kt

      //切換ui線程
                SwingUtilities.invokeLater{
                    continuation.resumeWithException(HttpException(reponseBody.code()))
                }

package com.yzdzy.kotlin.chapter7.basic

import cn.kotliner.coroutine.common.HttpError
import cn.kotliner.coroutine.common.HttpException
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import cn.kotliner.coroutine.ui.LOGO_URL
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import java.lang.Exception
import javax.swing.SwingUtilities
import javax.xml.ws.http.HTTPException
import kotlin.coroutines.resume
import kotlin.coroutines.resumeWithException
import kotlin.coroutines.startCoroutine
import kotlin.coroutines.suspendCoroutine

fun 我要開始協程了(block: suspend () -> Unit) {
    block.startCoroutine(BaseCoroutines())
}

suspend fun 我要開始加載圖片了(url: String) = suspendCoroutine<ByteArray> { continuation ->

    AsyncTask {

        log("耗時下載圖片")
        try {
            val reponseBody = HttpService.service.getLogo(LOGO_URL).execute()
            if (reponseBody.isSuccessful) {
                reponseBody.body()?.byteStream()?.readBytes()?.let{
                    //切換ui線程
                    SwingUtilities.invokeLater{
                        continuation.resume(it)
                    }
                }

            } else {
                //切換ui線程
                SwingUtilities.invokeLater{
                    continuation.resumeWithException(HttpException(reponseBody.code()))
                }

            }
        } catch (e: Exception) {
            SwingUtilities.invokeLater{
                continuation.resumeWithException(e)
            }

        }
    }.execute()
}

可以看到上面用了三次的

SwingUtilities.invokeLater{

爲了簡化

繼續在 async 包中新建 UiCotinuationWrapper.kt

package com.yzdzy.kotlin.chapter7.async

import javax.swing.SwingUtilities
import kotlin.coroutines.Continuation

/**
 * Created by benny on 5/29/17.
 */
class UiCotinuationWrapper<T>(val continuation: Continuation<T>): Continuation<T>{
    override val context = continuation.context

    override fun resumeWith(result: Result<T>) {
        SwingUtilities.invokeLater { continuation.resumeWith(result) }
    }

}

BaseCoroutines.kt 就可以寫成

package com.yzdzy.kotlin.chapter7.basic

import cn.kotliner.coroutine.common.HttpException
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import cn.kotliner.coroutine.ui.LOGO_URL
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import com.yzdzy.kotlin.chapter7.async.UiCotinuationWrapper
import java.lang.Exception
import javax.swing.SwingUtilities
import kotlin.coroutines.resume
import kotlin.coroutines.resumeWithException
import kotlin.coroutines.startCoroutine
import kotlin.coroutines.suspendCoroutine

fun 我要開始協程了(block: suspend () -> Unit) {
    block.startCoroutine(BaseCoroutines())
}

suspend fun 我要開始加載圖片了(url: String) = suspendCoroutine<ByteArray> { continuation ->
    AsyncTask {
        val uiCotinuationWrapper = UiCotinuationWrapper(continuation)
        log("耗時下載圖片")
        try {
            val reponseBody = HttpService.service.getLogo(LOGO_URL).execute()
            if (reponseBody.isSuccessful) {
                reponseBody.body()?.byteStream()?.readBytes()?.let {
                    //切換ui線程

                    uiCotinuationWrapper.resume(it)

                }

            } else {
                //切換ui線程

                uiCotinuationWrapper.resumeWithException(HttpException(reponseBody.code()))


            }
        } catch (e: Exception) {

            uiCotinuationWrapper.resumeWithException(e)


        }
    }.execute()
}

運行下效果不變

但是仍然定義了 val uiCotinuationWrapper = UiCotinuationWrapper(continuation)

然後再使用 uiCotinuationWrapper 調用其他方法感覺仍然不方便

啊哦上面log錯了一個地方這個地方改一下

package cn.kotliner.coroutine.ui


import cn.kotliner.coroutine.common.HttpError
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import com.yzdzy.kotlin.chapter7.basic.我要開始加載圖片了
import com.yzdzy.kotlin.chapter7.basic.我要開始協程了
import okhttp3.ResponseBody
import retrofit2.Call
import retrofit2.Callback
import retrofit2.HttpException
import retrofit2.Response
import javax.swing.JFrame.EXIT_ON_CLOSE
import javax.swing.SwingUtilities

/**
 * Created by benny on 5/20/17.
 */
const val LOGO_URL = "http://www.imooc.com/static/img/index/logo.png?t=1.1"

fun main(args: Array<String>) {
    val frame = MainWindow()
    frame.title = "Coroutine@Bennyhuo"
    frame.setSize(200, 150)
    frame.isResizable = true
    frame.defaultCloseOperation = EXIT_ON_CLOSE
    frame.init()
    frame.isVisible = true

    frame.onButtonClick {

        log("協程之前")
        我要開始協程了 {
            log("協程開始")
            val imageDate = 我要開始加載圖片了(LOGO_URL)
            log("拿到圖片")
            frame.setLogo(imageDate)
        }
        log("協程之後")
    }


}

就是

log("協程之後")
的位置錯了

繼續剛纔不方便的問題。這次通過攔截器實現

在async包中新建 AsyncContext.kt

package com.yzdzy.kotlin.chapter7.async

import kotlin.coroutines.AbstractCoroutineContextElement
import kotlin.coroutines.Continuation
import kotlin.coroutines.ContinuationInterceptor

class AsyncContext :AbstractCoroutineContextElement(ContinuationInterceptor),ContinuationInterceptor{
    override fun <T> interceptContinuation(continuation: Continuation<T>): Continuation<T> {
        return UiCotinuationWrapper(continuation.context.fold(continuation){
            continuation, element ->
            if(element!=this&&element is ContinuationInterceptor){
                element.interceptContinuation(continuation)
            }else continuation
        })
    }

}

修改Corutines.kt

package com.yzdzy.kotlin.chapter7.basic

import kotlin.coroutines.Continuation
import kotlin.coroutines.CoroutineContext
import kotlin.coroutines.EmptyCoroutineContext


class BaseCoroutines(val content: CoroutineContext = EmptyCoroutineContext) : Continuation<Unit> {
    override val context: CoroutineContext
        get() = EmptyCoroutineContext

    override fun resumeWith(result: Result<Unit>) {
    }

}

修改BaseCoroutines.kt

package com.yzdzy.kotlin.chapter7.basic

import cn.kotliner.coroutine.common.HttpException
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import cn.kotliner.coroutine.ui.LOGO_URL
import com.yzdzy.kotlin.chapter7.async.AsyncContext
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import com.yzdzy.kotlin.chapter7.async.UiCotinuationWrapper
import java.lang.Exception
import javax.swing.SwingUtilities
import kotlin.coroutines.resume
import kotlin.coroutines.resumeWithException
import kotlin.coroutines.startCoroutine
import kotlin.coroutines.suspendCoroutine

fun 我要開始協程了(block: suspend () -> Unit) {
    block.startCoroutine(BaseCoroutines(AsyncContext() ))
}

suspend fun 我要開始加載圖片了(url: String) = suspendCoroutine<ByteArray> { continuation ->
    AsyncTask {
        log("耗時下載圖片")
        try {
            val reponseBody = HttpService.service.getLogo(LOGO_URL).execute()
            if (reponseBody.isSuccessful) {
                reponseBody.body()?.byteStream()?.readBytes()?.let {
                    //切換ui線程

                    continuation.resume(it)

                }

            } else {
                //切換ui線程

                continuation.resumeWithException(HttpException(reponseBody.code()))


            }
        } catch (e: Exception) {

            continuation.resumeWithException(e)


        }
    }.execute()
}

運行看效果

完美

還可以接續優化把異步部分提取處理啊

修改BaseCoroutines.kt

package com.yzdzy.kotlin.chapter7.basic

import cn.kotliner.coroutine.common.HttpError
import cn.kotliner.coroutine.common.HttpException
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import cn.kotliner.coroutine.ui.LOGO_URL
import com.yzdzy.kotlin.chapter7.async.AsyncContext
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import com.yzdzy.kotlin.chapter7.async.UiCotinuationWrapper
import java.lang.Exception
import javax.swing.SwingUtilities
import kotlin.coroutines.*

fun 我要開始協程了(block: suspend () -> Unit) {
    block.startCoroutine(BaseCoroutines(AsyncContext()))
}

suspend fun <T> 我要開始耗時操作了(block: () -> T) = suspendCoroutine<T> { continuation ->
    AsyncTask {
        log("異步操作開始前")
        try {
            continuation.resume(block())
        } catch (e: Exception) {
            continuation.resumeWithException(e)
        }
    }.execute()
}


fun 我要開始加載圖片了(url: String): ByteArray {
    log("下載圖片開始")
    val reponseBody = HttpService.service.getLogo(url).execute()
    if (reponseBody.isSuccessful) {
        reponseBody.body()?.byteStream()?.readBytes()?.let {
            return it
        }
        throw HttpException(HttpError.HTTP_ERROR_NO_DATA)
    } else {
        //切換ui線程
        throw HttpException(reponseBody.code())
    }

}

修改main

package cn.kotliner.coroutine.ui


import cn.kotliner.coroutine.common.HttpError
import cn.kotliner.coroutine.common.HttpService
import cn.kotliner.coroutine.common.log
import com.yzdzy.kotlin.chapter7.async.AsyncTask
import com.yzdzy.kotlin.chapter7.basic.我要開始加載圖片了
import com.yzdzy.kotlin.chapter7.basic.我要開始協程了
import com.yzdzy.kotlin.chapter7.basic.我要開始耗時操作了
import okhttp3.ResponseBody
import retrofit2.Call
import retrofit2.Callback
import retrofit2.HttpException
import retrofit2.Response
import javax.swing.JFrame.EXIT_ON_CLOSE
import javax.swing.SwingUtilities

/**
 * Created by benny on 5/20/17.
 */
const val LOGO_URL = "http://www.imooc.com/static/img/index/logo.png?t=1.1"

fun main(args: Array<String>) {
    val frame = MainWindow()
    frame.title = "Coroutine@Bennyhuo"
    frame.setSize(200, 150)
    frame.isResizable = true
    frame.defaultCloseOperation = EXIT_ON_CLOSE
    frame.init()
    frame.isVisible = true

    frame.onButtonClick {

        log("協程之前")
        我要開始協程了 {
            log("協程開始")
            val imageDate = 我要開始耗時操作了 {
                我要開始加載圖片了(LOGO_URL)
            }
            log("拿到圖片")
            frame.setLogo(imageDate)
        }
        log("協程之後")
    }


}

效果不變

【40】kotlin 協程異步下載圖片3

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git 批量解決。both modified:

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結

【40】kotlin 協程 異步下載圖片3

【40】kotlin 協程異步下載圖片3