为什么android-inapp-billing-v3库需要两次购买？

我正在尝试使用android-inapp-billing-v3库在我的简单应用程序中实现应用内购买 . 我正在使用这个库（https://github.com/anjlab/android-inapp-billing-v3）

我遇到了一个奇怪的问题：您需要点击“购买”按钮两次才能购买此产品 . 让我一步一步解释我的意思 .

我们的产品未被购买，我们点击“购买”按钮，Google Play窗口出现在此处，我们点击“购买”并看到我们的交易成功完成，然后我们点按任意位置以使Google Play窗口消失，而不是输入onProductPurchased（ . . ）nothnig hapens . 好的，我们点击了“购买”按钮，并且没有任何其他Google Play窗口onProductPUrchased被访问 . 我不知道这是图书馆或我的实施中的某种错误 . （对不起我的英语不好）

这是我的代码：

public class BillingActivity extends Activity implements BillingProcessor.IBillingHandler {
    BillingProcessor bp;


    public final static String EXTRA_MESSAGE = "kepardvpn.client.MESSAGE";
    private String LOG_TAG = "BillingActivity";


    int mFlag;
    private String mResult;
    private String mEmail;
    private String mPassword;
    private Functions mFunctions;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Intent intent = getIntent();
        mFlag = intent.getFlags();
        mEmail = intent.getStringExtra(MainActivity.EMAIL);
        mFunctions = Globals.mFunctions;


        mPassword = intent.getStringExtra(MainActivity.PASSWORD);

        bp = new BillingProcessor(this, null, this);

        mFunctions.AddLog(2, LOG_TAG, "onCreate");
    }

    // IBillingHandler implementation

    @Override
    public void onBillingInitialized() {
        /*
         * Called then BillingProcessor was initialized and its ready to purchase
         */
        mFunctions.AddLog(2, LOG_TAG, "onBillignInitilized ");
        try {
            switch (mFlag) {
                case 0: {
                    mFunctions.AddLog(2, LOG_TAG, "pay_per_month");
                    bp.purchase(this, "pay_per_month");
                }
                break;
                case 1: {
                    mFunctions.AddLog(2, LOG_TAG, "pay_per_month");
                    bp.purchase(this, "pay_per_year");
                }
                break;
            }
        } catch (Exception e) {
            mFunctions.AddLog(2, LOG_TAG, "onBillingInitialized exception:" + e.getMessage());
        }
    }

    @Override
    public void onProductPurchased(String productId, TransactionDetails details) {
          /*
           * Called then requested PRODUCT ID was successfully purchased
           */
        mFunctions.AddLog(2, LOG_TAG, "Product successfully puchased");
        try {
            if (bp.consumePurchase(productId))  // imediatly after puchase consume product
            {
                mFunctions.AddLog(2, LOG_TAG, "onProductPurchased " + "product have been consumed");
                String obj = StringToJsonObject("action", "checkPayment", "email", mEmail, "password", mPassword,
                        "d", "android", "responseData", java.net.URLEncoder.encode(details.purchaseInfo.responseData, "utf-8"),
                        "signature", java.net.URLEncoder.encode(details.purchaseInfo.signature, "utf-8"), "response", "text");

                mFunctions.setPaymentResponseData(details.purchaseInfo.responseData);
                mFunctions.setPaymentSignature(details.purchaseInfo.signature);
                mFunctions.ActivatePayAccountTask(obj);
                //mFunctions.updatePreferences();

            } else // product could not have been consumed
            {
                mFunctions.AddLog(2, LOG_TAG, "onProductPurchased " + "product could not have been consumed");
            }
        } catch (Exception e) {
            mFunctions.AddLog(2, LOG_TAG, "onProductPurchased exception:" + e.getMessage());

        }
        ;

    }

    @Override
    public void onBillingError(int errorCode, Throwable error) {

        switch (errorCode) {
            case Constants.BILLING_RESPONSE_RESULT_DEVELOPER_ERROR:

                mFunctions.AddLog(2, LOG_TAG, "onBillingError," + "Invalid arguments provided to the API." + "Error code:" + errorCode);
                break;
            case Constants.BILLING_RESPONSE_RESULT_BILLING_UNAVAILABLE:
                sendMessage(getString(R.string.billing_not_supported_message));
                break;
            case Constants.BILLING_RESPONSE_RESULT_USER_CANCELED:
                mFunctions.AddLog(2, LOG_TAG, "onBillingError," + "User canceled purchase");
                break;
        }
        mFunctions.AddLog(2, LOG_TAG, "Error code:" + errorCode);
    }


    @Override
    public void onDestroy() {
        if (bp != null)
            bp.release();
        mFunctions.AddLog(2, LOG_TAG, "onDestroy");
        super.onDestroy();
    }

    @Override
    public void onPurchaseHistoryRestored() {
        /*
         * Called then purchase history was restored and the list of all owned PRODUCT ID's
         * was loaded from Google Play
         */
        mFunctions.AddLog(2, LOG_TAG, "onPurchasedHistoryRestored");
    }

    void sendMessage(String message) {        
        mFunctions.ShowError(message);
    }

    public String StringToJsonObject(String... val) {
        JSONObject obj = new JSONObject();
        try {
            for (int i = 0; i < val.length - 1; i += 2) {
                obj.put(val[i], val[i + 1]);
            }
        } catch (Exception e) {
        }
        return obj.toString();
    }

}