google obb（三）从自己cdn上下载(支持断点续传)

支持断点续传

参考网址

https://www.twblogs.net/a/5b8b35ad2b717718832e0bb6/zh-cn

https://blog.csdn.net/AnYuanLzh/article/details/70848442

当然还需要判断

网络是否连接、当前非wifi提示是否手机下载、obb下载完毕校验obb是否正确

你可能还需要了解：

1、修改Unity导出Android工程启动时黑屏，启动时间过长

2、obb下载完毕重启Activity读取obb数据文件

    /**
     * 重启Activity
     * @param context
     */
    public static void restartApplication(Activity context) {
        PackageManager packageManager = context.getPackageManager();
        Intent intent = packageManager.getLaunchIntentForPackage(context.getPackageName());
        ComponentName componentName = intent.getComponent();
        Intent mainIntent = IntentCompat.makeRestartActivityTask(componentName);
        mainIntent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
        context.startActivity(mainIntent);
        System.exit(0);
    }

可能报错： 

System.Net.WebException: Error getting response stream (Write: The authentication or decryption has failed.): SendFailure ---> 
System.IO.IOException: The authentication or decryption has failed. ---> 
Mono.Security.Protocol.Tls.TlsException: Invalid certificate received from server. Error code: 0xffffffff800b010ay

报错原因：

1、下载地址https，证书失效导致报错(我这边出现的问题，http没问题)

解决方式：

参考地址：https://linxinfa.blog.csdn.net/article/details/93190303 (简单测试可行)

参考文档：https://github.com/swagger-api/swagger-codegen/issues/3505