Android 缓存位图代码

有谁能注释掉这段代码，让我更好地了解这段代码中发生了什么

谢谢

private void putBitmapInDiskCache(Uri url, Bitmap avatar) {     
File cacheDir = new   File(context.getCacheDir(), "thumbnails");   
File cacheFile = new File(cacheDir, ""+url.hashCode());    
 try {      
  cacheFile.createNewFile();       
  FileOutputStream fos = new FileOutputStream(cacheFile);      
 avatar.compress(CompressFormat.PNG, 100, fos);       
 fos.flush();       
 fos.close();    
 } catch (Exception e) {      
Log.e(LOG_TAG, "Error when saving image to cache. ", e);     
}  
 } 

阅读它们时，它们是相似的：

fis = new FileInputStream(cacheFile);   
Bitmap local = BitmapFactory.decodeStream(fis); 

第二部分：

// Open input stream to the cache file
fis = new FileInputStream(cacheFile); 
// Read a bitmap from the file (which presumable contains bitmap in PNG format, since
// that's how files are created)
Bitmap local = BitmapFactory.decodeStream(fis); 

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更新为包含第二部分在第二部分中，CachFile部分中包含什么？我如何知道缓存文件的名称？大概该文件的名称仍然是url的哈希，字符串cacheFile=“”+url.hashCode（）；/“+int是将int转换为string的缩写。您能回答这个问题吗？必须添加以下代码行。如果（！cacheDir.exists（））cacheDir.mkdir（）；

// Open input stream to the cache file
fis = new FileInputStream(cacheFile); 
// Read a bitmap from the file (which presumable contains bitmap in PNG format, since
// that's how files are created)
Bitmap local = BitmapFactory.decodeStream(fis);