Android Open source Framework Imageloader: three-level caching mechanism for loading images

Preface:An open source framework that can download a level three cache mechanism from Https://github.com/nostra13/Android-Universal-Image-Loader. The following is a brief introduction to the main common methods in this framework, and mastering these methods will basically deal with the needs of most image downloads.
Note:The following code is a schematic snippet, read it carefully and you should know how to use it. Blue is represented as a class in the open source framework.

1. Initialize the Imageloader class object:

Imageloader Imageloader = Imageloader.getinstance (); Imageloader.stop ();     Stop loading picture Imageloader.clearmemorycache ();     Clear Memory cache Imageloader.cleardisccache ();       Clear the cache from the SD card

2. In the adapter GetView () method, display the Imageloader.displayimage () method of the ImageView Picture:

  Imageloadinglistener Animatefirstlistener = new Animatefirstdisplaylistener (); /** * Show Picture * parameter 1: Picture URL * Parameter 2: Control showing picture * Parameter 3: Display picture Settings * Parameter 4: Listener */Imageloader.displayimage (imag    Eurl, Holder.image, Options, Animatefirstlistener);      Add the picture display task to the execution pool, and the picture will be displayed to ImageView when it turns to this imageView imageloader.displayimage (IMAGEURL, ImageView, Options);                  Parameters passed in anonymous inner class imageloader.displayimage (IMAGEURL, ImageView, Options, new Simpleimageloadinglistener () {                  @Override public void onloadingstarted (String imageuri, view view) {//To display a progress bar } @Override public void onloadingfailed (String imageuri, view view, Failre                      Ason Failreason) {String message = NULL;                              Switch (Failreason.gettype ()) {//Get Picture failure type Case IO_ERROR://File I/O error    Message = "Input/output error";                          Break                              Case DECODING_ERROR://Decoding error message = "Image can ' t be decoded";                          Break                              Case network_denied://Network delay message = "Downloads is DENIED";                          Break                              Case Out_of_memory://Insufficient memory message = "Out of the memory error";                          Break                              Case UNKNOWN://reason unknown message = "UNKNOWN error";                      Break                   } toast.maketext (context, message, Toast.length_short). Show (); } @Override public void Onloadingcomplete (String imageuri, view view, Bitmap Loadedimag   e) {//Do not show circular progress bar}});

3. The parameters of the above 2. Imageloader.displayimage () method are options:

Displayimageoptions options;        Displayimageoptions is the class for setting up picture display options = new Displayimageoptions.builder ()      . Showstubimage (r.drawable.ic_stub )          //Set the picture to be displayed during picture download      . Showimageforemptyuri (R.drawable.ic_empty)  //Set the picture to be displayed when the image URI is empty or wrong.      Showimageonfail (R.drawable.ic_error)       //sets the picture to display when an error occurs during picture loading or decoding          . Cacheinmemory (True)                        // Sets whether the downloaded picture is in memory      . Cacheondisc (True)                          //sets whether the downloaded picture is slow to exist on the SD card  . Bitmapconfig (Bitmap.Config.RGB_565)     Sets the decoding type of the picture      . Displayer (new Roundedbitmapdisplayer)  //Set rounded picture      . Build ();                                   To create a configured Displayimageoption object

4. Parameter Animatefirstlistener of the above 2. Imageloader.displayimage () Method:

/*** picture loading the first time the listener is displayed * @author administrator**/  private static class Animatefirstdisplaylistener extends Simpleimageloadinglistener {      static final list<string> displayedimages = collections.synchronizedlist (new Linkedlist<string> ());      @Override public      void Onloadingcomplete (String imageuri, view view, Bitmap loadedimage) {          if (loadedimage! = null {              ImageView ImageView = (ImageView) view;              Whether to display the              boolean firstdisplay =!displayedimages.contains (Imageuri) for the first time;              if (firstdisplay) {                  //Picture fade-                  in effect fadeinbitmapdisplayer.animate (ImageView, n);                  Displayedimages.add (Imageuri);}}}      

5. The framework is primarily the above approach, which can also be understood below:

Listview.setonscrolllistener (New Pauseonscrolllistener (Imageloader, True, false));// A bunch of picture links com.nostra13.example.universalimageloader.constants.images;//the keys for passing extra parameters in intent: " Com.nostra13.example.universalimageloader.IMAGES "; com.nostra13.example.universalimageloader.constants.extra.images//the key to pass the Extra parameter in intent: " Com.nostra13.example.universalimageloader.IMAGE_POSITION " Com.nostra13.example.universalimageloader.Constants.Extra.IMAGE_POSITION

Android Open source Framework Imageloader: three-level caching mechanism for loading images