使用自定义方法

mBmpDial = decodeResource( getResources(),
                R.drawable.android_clock_dial );

private Bitmap decodeResource(Resources resources, int id) {
        TypedValue value = new TypedValue();
        resources.openRawResource( id, value );
        BitmapFactory.Options opts = new BitmapFactory.Options();
        opts.inTargetDensity = value.density;//获取当前手机运行环境的手机密度
        opts.inScaled = false;
        return BitmapFactory.decodeResource( resources, id, opts );
    }

``