为什么Android官方废弃SoftRefrerence软引用和WeakReference弱引用，而拥抱LruCache？
一些具有Java背景的研发者喜欢使用软引用(SoftRefrerence)和弱引用(WeakReference)来缓存Java对象和数据，但是如果在Android中仍然使用软引用(SoftRefrerence)和弱引用(WeakReference)，会极易导致Android程序闪退崩溃，谷歌Android官方从Android 3.0以后，强烈建议开发者不要在Android中使用软引用(SoftRefrerence)和弱引用(WeakReference)，Android的谷歌官方解释（原文）：
Note: In the past, a popular memory cache implementation was a SoftReference or WeakReference bitmap cache, however this is not recommended. Starting from Android 2.3 (API Level 9) the garbage collector is more aggressive with collecting soft/weak references which makes them fairly ineffective. In addition, prior to Android 3.0 (API Level 11), the backing data of a bitmap was stored in native memory which is not released in a predictable manner, potentially causing an application to briefly exceed its memory limits and crash.这段内容大致翻译出来是这样的（英文对照翻译）：
Note: In the past, a popular memory cache implementation was a SoftReference or WeakReference bitmap cache, however this is not recommended. Starting from Android 2.3 (API Level 9) the garbage collector is more aggressive with collecting soft/weak references which makes them fairly ineffective. In addition, prior to Android 3.0 (API Level 11), the backing data of a bitmap was stored in native memory which is not released in a predictable manner, potentially causing an application to briefly exceed its memory limits and crash.
注意！在过去，一个非常流行的内存缓存实现是通过SoftReference或WeakReference对bitmap进行缓存，然而现在不推荐使用这种方案实施内存缓存了。从Android系统版本2.3 ( API Level 9 )以后，garbage collector（译者注：Java垃圾回收器）会更加积极的回收持有软/弱引用对象，这导致软引用和弱引用变的相当无能为力。除此之外，在Android系统版本3.0 ( API Level 11 )之前，在本地内存中缓存一个bitmap数据并不会以预期的方式释放，这可能导致一个应用在很短期间就超越它的内存上限（译者注：进而会引发OOM，Out Of Memory）而导致应用崩溃。时至今日，网上搜一搜Android缓存技术，有感于当下竟然还有一些文章在给开发者推荐使用SoftRefrerence软引用和WeakReference弱引用缓存数据，不禁令人唏嘘。
附录：
1，《使用Android新式LruCache缓存图片，基于线程池异步加载图片》链接：https://blog.csdn.net/zhangphil/article/details/44082287
2，《使用新式LruCache取代SoftReference缓存图片，Android异步加载图片》链接：https://blog.csdn.net/zhangphil/article/details/43667415
3，Android谷歌官方解释为何要极力避免在Android程序中使用WeakReference弱引用与SoftReference软引用？谷歌官方英文文档链接地址：http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
