从URL中保存图库图像的状态？

Question

我有两个图像从一个URL到我的画廊视图。但是当我去其他活动时，图像再次从网上重新加载。我想每个应用程序实例请求一次。我将如何去拯救这个状态？

/** Simple Constructor saving the 'parent' context. */ 
       public ImageAdapter(Context c) { this.myContext = c; } 

       /** Returns the amount of images we have defined. */ 
       public int getCount() { return this.myRemoteImages.length; } 

       /* Use the array-Positions as unique IDs */ 
       public Object getItem(int position) { return position; } 
       public long getItemId(int position) { return position; } 

       /** Returns a new ImageView to 
       * be displayed, depending on 
       * the position passed. */ 
       public View getView(int position, View convertView, ViewGroup parent) { 
       ImageView i = new ImageView(this.myContext); 

       try { 
           /* Open a new URL and get the InputStream to load data from it. */ 
           URL aURL = new URL(myRemoteImages[position]); 
           URLConnection conn = aURL.openConnection(); 
           conn.connect(); 
           InputStream is = conn.getInputStream(); 
           /* Buffered is always good for a performance plus. */ 
           BufferedInputStream bis = new BufferedInputStream(is); 
           /* Decode url-data to a bitmap. */ 
           Bitmap bm = BitmapFactory.decodeStream(bis); 
           bis.close(); 
           is.close(); 

           /* Apply the Bitmap to the ImageView that will be returned. */ 
           i.setImageBitmap(bm); 
         } catch (IOException e) { 

           Log.e("DEBUGTAG", "Remtoe Image Exception", e); 
         } 

       /* Image should be scaled as width/height are set. */ 
       i.setScaleType(ImageView.ScaleType.FIT_CENTER); 
       /* Set the Width/Height of the ImageView. */ 
       i.setLayoutParams(new Gallery.LayoutParams(150, 150)); 
       return i; 
       } 

       /** Returns the size (0.0f to 1.0f) of the views 
       * depending on the 'offset' to the center. */ 
       public float getScale(boolean focused, int offset) { 
       /* Formula: 1/(2^offset) */ 
       return Math.max(0, 1.0f/(float)Math.pow(2, Math.abs(offset))); 
       } 
       } 
      public class ImageAdapter2 extends BaseAdapter { 
       /** The parent context */ 
       private Context myContext;public ImageAdapter2() { 
        // TODO Auto-generated constructor stub 
       } 
       /** URL-Strings to some remote images. */ 

       private String[] myRemoteImages = {imageUrl2}; 






       /** Simple Constructor saving the 'parent' context. */ 
       public ImageAdapter2(Context c) { this.myContext = c; } 

       /** Returns the amount of images we have defined. */ 
       public int getCount() { return this.myRemoteImages.length; } 

       /* Use the array-Positions as unique IDs */ 
       public Object getItem(int position) { return position; } 
       public long getItemId(int position) { return position; } 

       /** Returns a new ImageView to 
       * be displayed, depending on 
       * the position passed. */ 
       public View getView(int position, View convertView, ViewGroup parent) { 
       ImageView i = new ImageView(this.myContext); 

       try { 
           /* Open a new URL and get the InputStream to load data from it. */ 
           URL aURL = new URL(myRemoteImages[position]); 
           URLConnection conn = aURL.openConnection(); 
           conn.connect(); 
           InputStream is = conn.getInputStream(); 
           /* Buffered is always good for a performance plus. */ 
           BufferedInputStream bis = new BufferedInputStream(is); 
           /* Decode url-data to a bitmap. */ 
           Bitmap bm = BitmapFactory.decodeStream(bis); 
           bis.close(); 
           is.close(); 

           /* Apply the Bitmap to the ImageView that will be returned. */ 
           i.setImageBitmap(bm); 
         } catch (IOException e) { 

           Log.e("DEBUGTAG", "Remtoe Image Exception", e); 
         } 

       /* Image should be scaled as width/height are set. */ 
       i.setScaleType(ImageView.ScaleType.FIT_CENTER); 
       /* Set the Width/Height of the ImageView. */ 
       i.setLayoutParams(new Gallery.LayoutParams(150, 150)); 
       return i; 
       } 

       /** Returns the size (0.0f to 1.0f) of the views 
       * depending on the 'offset' to the center. */ 
       public float getScale(boolean focused, int offset) { 
       /* Formula: 1/(2^offset) */ 
       return Math.max(0, 1.0f/(float)Math.pow(2, Math.abs(offset))); 




       } 
} 

Answer 1

您可以在单独的图像保存为静态的，或者你可以把他们的HashMap（键URL，值图像的位图）以备后用，或者你可以做图片的懒惰下载或最后你可以使用应用程序（请参阅http://developer.android.com/reference/android/app/Application.html以维护全局状态），但存储图像并不是件好事（通常会造成内存问题），请每次使用延迟加载下载它们。