首先檢查app包名、安裝在手機上的簽名和微信開放平臺上面填寫的包名、簽名是否一致，如果不一致請改成一致。
public class MyApp extends Application {
    public static IWXAPI api;//此物件是專門用來向微信傳送資料的一個重要介面,使用強引用持有,所有的資訊傳送都是基於這個物件的

    @Override
    public void onCreate() {
        super.onCreate();
        api = WXAPIFactory.createWXAPI(this, ShareKeys.WX_APPID, false);
        api.registerApp(ShareKeys.WX_APPID);
    }
}

在微信登陸、分享、支付時統一用 MyApp.api.xxx();

比如

    微信登陸

final SendAuth.Req req = new SendAuth.Req();
req.scope = "snsapi_userinfo";//
req.state = "mcl";
MyApp.api.sendReq(req);

   微信分享

WXWebpageObject webpage=new WXWebpageObject();
webpage.webpageUrl="https://www.baidu.com/";
WXMediaMessage msg = new WXMediaMessage(webpage);
msg.title = "app名稱";
msg.description = "mcl";
Bitmap thumb = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
msg . thumbData = bmpToByteArray (thumb, true) ;

SendMessageToWX.Req req = new SendMessageToWX.Req();
req.transaction = buildTransaction("webpage");
req.message = msg;
req.scene = wechat;
MyApp.api.sendReq(req);
 

  微信支付

MyApp.api.registerApp(weChatPayResult.getAppid());
PayReq request = new PayReq();
request.appId = weChatPayResult.getAppid();
request.partnerId = weChatPayResult.getPartnerid();
request.prepayId = weChatPayResult.getPrepayid();
request.packageValue = weChatPayResult.getPackageX();
request.nonceStr = weChatPayResult.getNoncestr();
request.timeStamp = String.valueOf(weChatPayResult.getTimestamp());
request.sign = weChatPayResult.getSign();
MyApp.api.sendReq(request);