Preload multiple images with Glide

Question

We are trying to preload images into cache memory to load them later (the images are located in the Asset folder of the application)

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Answer 1

//i can give you a solution

/**
 * 1.reflect some objects inside Glide
 */
fun prepareGlideObjects() {
    if (!enableFunctions || atomicPrepare.getAndSet(true)) {
        return
    }
    var t = LogTime.getLogTime()
    glide = Glide.get(BasicConfig.getInstance().appContext)
    if (diskCache == null) {
        val engine = getObject(glide, "engine")
        val diskCacheProvider = getObject(engine, "diskCacheProvider")
        val method = diskCacheProvider!!::class.java.getDeclaredMethod("getDiskCache")
        method.isAccessible = true
        diskCache = method.invoke(diskCacheProvider) as DiskCache
    }
    if (arrayPool == null) {
        arrayPool = getObject(glide, "arrayPool") as ArrayPool
    }
    if (decoder == null) {
        val registry = getObject(glide, "registry") as Registry
        val decoderRegistry = getObject(registry, "decoderRegistry") as ResourceDecoderRegistry
        val map = getObject(decoderRegistry, "decoders") as HashMap<*, *>
        val list = map["Bitmap"] as List<*>
        val o = list[0]
        decoder = getObject(o, "decoder") as ByteBufferBitmapDecoder
    }
    Log.debug(TAG, "prepareGlideObjects:" + LogTime.getElapsedMillis(t))
    try {
        t = LogTime.getLogTime()
        //首次打开diskCache 耗时较大，此处是提前打开文件索引
        val url = GlideUrl("http://xx.cdn.yy.com/fake_pic.jpg")
        val dataCacheKey = DataCacheKey(url, EmptySignature.obtain())
        diskCache?.get(dataCacheKey)
        Log.debug(TAG, "_load_fake_pic:" + LogTime.getElapsedMillis(t))
    } catch (e: Throwable) {
        Log.error(TAG, "cold load failed:$e")
    }
}

/**
 *2.load bitmap-file from diskCache
 */
fun loadBitmap(url: String) {
    val gUrl = GlideUrl(url:String)
    val dataCacheKey = DataCacheKey(gUrl, EmptySignature.obtain())
    val file = diskCache?.get(dataCacheKey)
}

//3.decode bitmap from file
private fun extractBitmapFromFile(url: String, file: File) {
    try {
        val dimen = getDimensionFromUrl(url)
        val result = decoder?.decode(ByteBufferUtil.fromFile(file), dimen[0], dimen[1],
                Options()) as BitmapResource?
        result!!.initialize()
        //simple bitmap cache
        bitmapMap[url] = result.get()
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            Log.debug(TAG, "allocationByteCount:" +
                    bitmapMap[url]!!.allocationByteCount / 1024.0)
        }
    } catch (e: Throwable) {
        Log.error(TAG, "init result failed:$e")
    }
}

//4.decode file from http-stream
private fun decodeHttpStream() {
    val uri = GlideUrl(call?.request()?.url().toString())
    val contentLength = Preconditions.checkNotNull(responseBody).contentLength()
    val stream = ContentLengthInputStream.obtain(responseBody.byteStream(),
            contentLength)
    if (arrayPool == null) {
        //re prepare
        arrayPool = glide?.arrayPool
    }
    val encoder = StreamEncoder(arrayPool)
    val writer = DataCacheWriter(encoder, stream, Options())
    val originalKey = DataCacheKey(uri, EmptySignature.obtain())
    //ready,此处可以用来监控文件字节流写入本地文件的时间
    diskCache?.put(originalKey, writer)
    val file = diskCache?.get(uri)
}

//5.after these jobs done, load a bitmap from diskCache,it takes just 10ms。