Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.send_img);

//初始化 WXImageObject 和 WXMediaMessage 对象

WXImageObject imgObj = new WXImageObject(bmp);

WXMediaMessage msg = new WXMediaMessage();

msg.mediaObject = imgObj;

//设置缩略图

Bitmap thumbBmp = Bitmap.createScaledBitmap(bmp, THUMB_SIZE, THUMB_SIZE, true);

bmp.recycle();

msg.thumbData = Util.bmpToByteArray(thumbBmp, true);

//构造一个Req

SendMessageToWX.Req req = new SendMessageToWX.Req();

req.transaction = buildTransaction("img");

req.message = msg;

req.scene = mTargetScene;

req.userOpenId = getOpenId();

//调用api接口，发送数据到微信

api.sendReq(req);