结合实例讲解Glide资源回收与复用的常见场景应用

// RecyclerView.Adapter 中的 ViewHolder
class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    fun bind(url: String) {
        Glide.with(itemView)
            .load(url)
            .into(itemView.imageView)
    }

    fun clear() {
        Glide.with(itemView).clear(itemView.imageView) // 手动释放资源
    }
}

// 在 Adapter 中回收资源
override fun onViewRecycled(holder: MyViewHolder) {
    holder.clear()
    super.onViewRecycled(holder)
}

// Activity 或 Fragment 中
override fun onDestroy() {
    // 释放当前页面所有请求
    Glide.with(this).pauseRequests()
    // 或者直接清除所有关联请求
    Glide.with(this).clear(imageView)
    super.onDestroy()
}

class CustomTransformation : BitmapTransformation() {
    override fun transform(
        pool: BitmapPool,
        source: Bitmap,
        outWidth: Int,
        outHeight: Int
    ): Bitmap {
        // 从 BitmapPool 中复用内存
        val recycledBitmap = pool.get(outWidth, outHeight, Bitmap.Config.ARGB_8888)

        // 在复用的 Bitmap 上绘制内容（示例：灰度处理）
        val canvas = Canvas(recycledBitmap)
        val paint = Paint()
        val matrix = ColorMatrix().apply { setSaturation(0f) }
        paint.colorFilter = ColorMatrixColorFilter(matrix)
        canvas.drawBitmap(source, 0f, 0f, paint)

        return recycledBitmap
    }

    override fun updateDiskCacheKey(messageDigest: MessageDigest) {
        messageDigest.update("custom_transformation".toByteArray())
    }
}

// 手动清理内存缓存（需在主线程调用）
Glide.get(context).clearMemory()

// 在 Application 中监听内存压力
class MyApp : Application() {
    override fun onTrimMemory(level: Int) {
        super.onTrimMemory(level)
        if (level >= ComponentCallbacks2.TRIM_MEMORY_MODERATE) {
            Glide.get(this).clearMemory()
        }
    }
}

@GlideModule
class CustomGlideModule : AppGlideModule() {
    override fun applyOptions(context: Context, builder: GlideBuilder) {
        // 创建支持大尺寸 ARGB_8888 的 BitmapPool
        val bitmapPool = LruBitmapPool(
            maxSize = 1024 * 1024 * 100, // 100MB
            allowedConfigs = mutableListOf(Bitmap.Config.ARGB_8888),
            trackMutableBitmaps = true
        )
        builder.setBitmapPool(bitmapPool)
    }
}

// 自定义 Target
val target = object : CustomTarget<Bitmap>() {
    override fun onResourceReady(resource: Bitmap, transition: Transition<in Bitmap>?) {
        customView.setBitmap(resource)
    }

    override fun onLoadCleared(placeholder: Drawable?) {
        // 主动释放资源
        customView.setBitmap(null)
    }
}

// 加载并绑定生命周期
Glide.with(context)
    .asBitmap()
    .load(url)
    .into(target)

// 在适当时候释放
fun onDestroy() {
    Glide.with(context).clear(target)
}

// 存储资源
Glide.with(context)
    .load(url)
    .into(object : CustomTarget<Drawable>() {
        override fun onResourceReady(resource: Drawable, transition: Transition<in Drawable>?) {
            val key = Glide.get(context).memoryCache.generateKey(url, 100, 100)
            Glide.get(context).memoryCache.put(key, resource)
        }
    })

// 读取复用资源
val key = Glide.get(context).memoryCache.generateKey(url, 100, 100)
val cachedResource = Glide.get(context).memoryCache.get(key)
if (cachedResource != null) {
    imageView.setImageDrawable(cachedResource)
} else {
    Glide.with(context).load(url).into(imageView)
}