Android Studio中获取versionCode一直是1

/**
     * @return
     * 获取本地包
     */
    public int getVerCode()
    {
        int verCode = -1;
        try
        {
            verCode = getPackageManager().getPackageInfo(
                    "这里是应用的包名", 0).versionCode;
        } catch (PackageManager.NameNotFoundException e)
        {
        }
        return verCode;
    }

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.huaxin.yunnan.environment"
    android:versionCode="2"
    android:versionName="2.0">

defaultConfig {
        versionCode 2
        versionName "2.0"
    }