加载asset文件夹下边的图片

将asset中的图片文件加载到ImageView中

// load image          try {              // get input stream              InputStream ims = getAssets().open("avatar.jpg");              // load image as Drawable              Drawable d = Drawable.createFromStream(ims, null);              // set image to ImageView              mImage.setImageDrawable(d);          }          catch(IOException ex) {              return;          }  
将asset中的图片文件绘制到自定义View中。
Bitmap bitmap;		try {              InputStream ims = this.getContext().getAssets().open("fl.jpg");              // 读入图片并将其强转为 BitmapDrawable类型            BitmapDrawable bd = (BitmapDrawable) Drawable.createFromStream(ims, null);            bitmap = bd.getBitmap();            ims.close();        }          catch(IOException ex) {              return;          } 		//canvas.drawBitmap(bitmap, -200, -200, new Paint());		canvas.drawBitmap(bitmap, null, new Rect(-30,-40,30,40), new Paint());//null表示原图尺寸，第二个rect表示显示区域（位图会拉伸填充该区域）
在onDraw()中绘制位图需要用到的方法(源码):
    /**     * Draw the specified bitmap, scaling/translating automatically to fill     * the destination rectangle. If the source rectangle is not null, it     * specifies the subset of the bitmap to draw.     *     * <p>Note: if the paint contains a maskfilter that generates a mask which     * extends beyond the bitmap's original width/height (e.g. BlurMaskFilter),     * then the bitmap will be drawn as if it were in a Shader with CLAMP mode.     * Thus the color outside of the original width/height will be the edge     * color replicated.     *     * <p>This function <em>ignores the density associated with the bitmap</em>.     * This is because the source and destination rectangle coordinate     * spaces are in their respective densities, so must already have the     * apPRopriate scaling factor applied.     *     * @param bitmap The bitmap to be drawn     * @param src    May be null. The subset of the bitmap to be drawn     * @param dst    The rectangle that the bitmap will be scaled/translated     *               to fit into     * @param paint  May be null. The paint used to draw the bitmap     */    public void drawBitmap(@NonNull Bitmap bitmap, @Nullable Rect src, @NonNull RectF dst,            @Nullable Paint paint) {      if (dst == null) {          throw new NullPointerException();      }      throwIfCannotDraw(bitmap);      final long nativePaint = paint == null ? 0 : paint.getNativeInstance();      float left, top, right, bottom;      if (src == null) {          left = top = 0;          right = bitmap.getWidth();          bottom = bitmap.getHeight();      } else {          left = src.left;          right = src.right;          top = src.top;          bottom = src.bottom;      }      native_drawBitmap(mNativeCanvasWrapper, bitmap, left, top, right, bottom,              dst.left, dst.top, dst.right, dst.bottom, nativePaint, mScreenDensity,              bitmap.mDensity);  }