在我们的业务中,经常存在需要通过发送验证码、校验验证码来完成的一些业务逻辑,比如账号注册、找回密码、用户身份确认等。
在该类业务中,发送验证码的方式可以有各种各样,比如最常见的手机验证,最古老的邮箱验证,到现在相对少见的微信公众号、钉钉通知等;而验证码服务端存储的方式也可以各式各样,比如存储在关系型数据库中,当然也可以如本文标题所示,存储在Redis
中。
既然已经预见到了各式各样的发送方式,也预见到了各式各样的存储方式,所以,虽然本文标题是基于Redis
,但Redis
其实只是其中的一种存储方式,如果需要,我们也应该可以和方便的切换到其它存储方式。
上代码前,我们先看下设计中的接口关系
ICodeHelper
是最终提供发送验证码和校验验证码的最终接口,其关联了ICodeSender
和ICodeStorage
,ICodeSender
即为验证码发送方式的约定接口,ICodeStorage
则为验证码服务端持久化方式的约定接口。我们可以看到ICodeSender
同样关联了IContentFormatter
,因为作为发送方ICodeSender
其实是不知道如何将要发送的内容组织成一段完整的文本内容的,这时候就需要IContentFormatter
来组织文本内容,至于继承自IContentFormatter
的IComplexContentFormatter
,则只是IContentFormatter
一个容器封装,毕竟对于不同的业务类型,我们需要组织成不同的文本内容,通过IComplexContentFormatter
,我们可以将不同业务类型文本内容的组织过程,分散到不同的IContentFormatter
中。
下面我们来看下上述接口的规范约定,考虑到代码的简便性,此处我们简单的将receiver
接收方定义为了string
,而不是泛型<T>
;业务标志bizFlag
为了方便接入时无需调整代码,所以此处也没有将该值定义为枚举,而是同样定义成了通用性最强的string
。
ICodeStorage
/// <summary> /// 校验码信息存储接口 /// </summary> public interface ICodeStorage { /// <summary> /// 将校验码进行持久化,如果接收方和业务标志组合已经存在,则进行覆盖 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <returns></returns> Task<bool> SetCode(string receiver, string bizFlag, string code, TimeSpan effectiveTime); /// <summary> /// 校验码错误次数+1,如果校验码已过期,则不进行任何操作 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <returns></returns> Task IncreaseCodeErrors(string receiver, string bizFlag); /// <summary> /// 校验码发送次数周期持久化,如果接收方和业务标志组合已经存在,则进行覆盖 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="period">周期时间范围</param> /// <returns></returns> Task<bool> SetPeriod(string receiver, string bizFlag, TimeSpan? period); /// <summary> /// 校验码周期内发送次数+1,如果周期已到,则不进行任何操作 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <returns></returns> Task IncreaseSendTimes(string receiver, string bizFlag); /// <summary> /// 获取校验码及已尝试错误次数,如果校验码不存在或已过期,则返回null /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <returns></returns> Task<Tuple<string, int>> GetEffectiveCode(string receiver, string bizFlag); /// <summary> /// 获取校验码周期内已发送次数,如果周期已到或未发送过任何验证码,则返回0 /// </summary> /// <param name="receiver"></param> /// <param name="bizFlag"></param> /// <returns></returns> Task<int> GetAreadySendTimes(string receiver, string bizFlag); }
ICodeSender
,请注意IsSupport
方法约定。
/// <summary> /// 校验码实际发送接口 /// </summary> public interface ICodeSender { /// <summary> /// 发送校验码内容模板 /// </summary> IContentFormatter Formatter { get; } /// <summary> /// 判断接收者是否符合发送条件,例如当前发送者只支持邮箱,而接收方为手机号,则返回结果应当为false /// </summary> /// <param name="receiver">接收方</param> /// <returns></returns> bool IsSupport(string receiver); /// <summary> /// 发送校验码信息 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <returns></returns> Task<bool> Send(string receiver, string bizFlag, string code, TimeSpan effectiveTime); }
IContentFormatter
/// <summary> /// 发送校验码内容模板接口 /// </summary> public interface IContentFormatter { /// <summary> /// 将指定参数组织成待发送的文本内容 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <returns></returns> string GetContent(string receiver, string bizFlag, string code, TimeSpan effectiveTime); }
IComplexContentFormatter
/// <summary> /// 基于业务标志的多内容模板 /// </summary> public interface IComplexContentFormatter : IContentFormatter { /// <summary> /// 设置指定业务对应的内容模板 /// </summary> /// <param name="bizFlag">业务标志</param> /// <param name="formatter">内容模板</param> void SetFormatter(string bizFlag, IContentFormatter formatter); /// <summary> /// 移除指定业务对应的内容模板,如果没有,则返回null /// </summary> /// <param name="bizFlag">业务标志</param> /// <returns></returns> IContentFormatter RemoveFormatter(string bizFlag); }
ICodeHelper
/// <summary> /// 业务校验码辅助接口 /// </summary> public interface ICodeHelper { /// <summary> /// 校验码实际发送者 /// </summary> ICodeSender Sender { get; } /// <summary> /// 校验码信息存储者 /// </summary> ICodeStorage Storage { get; } /// <summary> /// 发送校验码 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <param name="maxSendLimit">周期内最大允许发送配置,为null则表示无限制</param> /// <returns></returns> Task<SendResult> SendCode(string receiver, string bizFlag, string code, TimeSpan effectiveTime, PeriodLimit maxSendLimit); /// <summary> /// 验证校验码是否正确 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="maxErrorLimit">最大允许错误次数</param> /// <returns></returns> Task<VerificationResult> VerifyCode(string receiver, string bizFlag, string code, int maxErrorLimit); }
下面则是接口约定中的一些定义的类和枚举。
/// <summary> /// 校验码发送周期设置 /// </summary> public class PeriodLimit { /// <summary> /// 周期内允许的最大次数 /// </summary> public int MaxLimit { get; set; } /// <summary> /// 周期时间,如果不设置,则表示无周期,此时<see cref="MaxLimit"/>代表总共只允许发送多少次 /// </summary> public TimeSpan? Period { get; set; } } /// <summary> /// 校验码发送结果 /// </summary> public enum SendResult { /// <summary> /// 发送成功 /// </summary> [Description("成功")] Success = 0, /// <summary> /// 超出最大发送次数 /// </summary> [Description("超出最大发送次数")] MaxSendLimit = 11, /// <summary> /// 发送失败,指<see cref="ICodeSender"/>的发送结果为false /// </summary> [Description("发送失败")] FailInSend = 12, /// <summary> /// 无法发送,<see cref="ICodeSender.IsSupport(string)"/>结果为false /// </summary> [Description("无法发送")] NotSupprot = 13, } /// <summary> /// 校验码校验结果 /// </summary> public enum VerificationResult { /// <summary> /// 校验成功 /// </summary> [Description("成功")] Success = 0, /// <summary> /// 校验码已过期 /// </summary> [Description("校验码已过期")] Expired = 31, /// <summary> /// 校验码不一致,校验失败 /// </summary> [Description("校验失败")] VerificationFailed = 32, /// <summary> /// 已经达到了最大错误尝试次数,需重新发送新的校验码 /// </summary> [Description("超出最大错误次数")] MaxErrorLimit = 33, }
再下来就是具体的接口实现了,当然这些实现也是通用实现
ContentFormatter
/// <summary> /// 通用的内容模板 /// </summary> public class ContentFormatter : IContentFormatter { private Func<string, string, string, TimeSpan, string> _func; /// <summary> /// 通用实现,这样就无需每种业务类型都要实现<see cref="IContentFormatter"/> /// </summary> /// <param name="func">传递的委托,参数顺序与<see cref="GetContent(string, string, string, TimeSpan)"/>一致</param> public ContentFormatter(Func<string, string, string, TimeSpan, string> func) { this._func = func ?? throw new ArgumentNullException(nameof(func)); } /// <summary> /// 将指定参数组织成待发送的文本内容 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <returns></returns> public string GetContent(string receiver, string bizFlag, string code, TimeSpan effectiveTime) { return this._func.Invoke(receiver, bizFlag, code, effectiveTime); } }
ComplexContentFormatter
using System.Collections.Concurrent; /// <summary> /// 基于业务标志的多内容模板实现 /// </summary> public class ComplexContentFormatter : IComplexContentFormatter { private ConcurrentDictionary<string, IContentFormatter> _dic = new ConcurrentDictionary<string, IContentFormatter>(); /// <summary> /// 设置指定业务对应的内容模板 /// </summary> /// <param name="bizFlag">业务标志</param> /// <param name="formatter">内容模板</param> public void SetFormatter(string bizFlag, IContentFormatter formatter) { if (!string.IsNullOrWhiteSpace(bizFlag) && formatter != null) { this._dic.AddOrUpdate(bizFlag, formatter, (k, v) => formatter); } } /// <summary> /// 移除指定业务对应的内容模板,如果没有,则返回null /// </summary> /// <param name="bizFlag">业务标志</param> /// <returns></returns> public IContentFormatter RemoveFormatter(string bizFlag) { if (!string.IsNullOrWhiteSpace(bizFlag) && this._dic.TryRemove(bizFlag, out IContentFormatter formatter)) { return formatter; } return null; } /// <summary> /// 将指定参数组织成待发送的文本内容 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <returns></returns> public string GetContent(string receiver, string bizFlag, string code, TimeSpan effectiveTime) { if (string.IsNullOrWhiteSpace(bizFlag)) { throw new ArgumentNullException(nameof(bizFlag)); } this._dic.TryGetValue(bizFlag, out IContentFormatter formatter); if (formatter == null) { throw new KeyNotFoundException(nameof(formatter)); } return formatter.GetContent(receiver, bizFlag, code, effectiveTime); } }
CodeHelper
,注意该类除了实现ICodeHelper
外,还提供了一个用于生成随机验证码的静态方法GetRandomNumber
。
/// <summary> /// 业务校验码辅助接口实现 /// </summary> public class CodeHelper : ICodeHelper { /// <summary> /// 基于接口实现,可依赖注入 /// </summary> /// <param name="sender"></param> /// <param name="storage"></param> public CodeHelper(ICodeSender sender, ICodeStorage storage) { this.Sender = sender ?? throw new ArgumentNullException(nameof(sender)); this.Storage = storage ?? throw new ArgumentNullException(nameof(storage)); } /// <summary> /// 校验码实际发送者 /// </summary> public ICodeSender Sender { get; } /// <summary> /// 校验码信息存储者 /// </summary> public ICodeStorage Storage { get; } /// <summary> /// 发送校验码 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <param name="maxSendLimit">周期内最大允许发送配置,为null则表示无限制</param> public async Task<SendResult> SendCode(string receiver, string bizFlag, string code, TimeSpan effectiveTime, PeriodLimit maxSendLimit) { var result = SendResult.NotSupprot; if (this.Sender.IsSupport(receiver)) { result = SendResult.MaxSendLimit; bool canSend = maxSendLimit == null; int sendTimes = 0; if (!canSend) { sendTimes = await this.Storage.GetAreadySendTimes(receiver, bizFlag).ConfigureAwait(false); canSend = sendTimes < maxSendLimit.MaxLimit; } if (canSend) { result = SendResult.FailInSend; if (await this.Sender.Send(receiver, bizFlag, code, effectiveTime).ConfigureAwait(false) && await this.Storage.SetCode(receiver, bizFlag, code, effectiveTime).ConfigureAwait(false)) { result = SendResult.Success; if (maxSendLimit != null) { if (sendTimes == 0) { await this.Storage.SetPeriod(receiver, bizFlag, maxSendLimit.Period).ConfigureAwait(false); } else { await this.Storage.IncreaseSendTimes(receiver, bizFlag).ConfigureAwait(false); } } } } } return result; } /// <summary> /// 验证校验码是否正确 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="maxErrorLimit">最大允许错误次数</param> /// <returns></returns> public async Task<VerificationResult> VerifyCode(string receiver, string bizFlag, string code, int maxErrorLimit) { var result = VerificationResult.Expired; var vCode = await this.Storage.GetEffectiveCode(receiver, bizFlag).ConfigureAwait(false); if (vCode != null && !string.IsNullOrWhiteSpace(vCode.Item1)) { result = VerificationResult.MaxErrorLimit; if (vCode.Item2 < maxErrorLimit) { result = VerificationResult.Success; if (!string.Equals(vCode.Item1, code, StringComparison.OrdinalIgnoreCase)) { result = VerificationResult.VerificationFailed; await this.Storage.IncreaseCodeErrors(receiver, bizFlag).ConfigureAwait(false); } } } return result; } /// <summary> /// 获取由数字组成的校验码 /// </summary> /// <param name="maxLength">校验码长度</param> /// <returns></returns> public static string GetRandomNumber(int maxLength = 6) { if (maxLength <= 0 || maxLength >= 10) { throw new ArgumentOutOfRangeException($"{nameof(maxLength)} must between {1} and {9}."); } var rd = Math.Abs(Guid.NewGuid().GetHashCode()); var tmpX = (int)Math.Pow(10, maxLength); return (rd % tmpX).ToString().PadLeft(maxLength, '0'); } }
除了上述标准通用实现,还有一些半通用实现,比如本文标题中的Redis
,所谓半通用,就是指你可以直接拿来用,但有可能不符合你的技术场景,此时你需要自己重写一份。
CodeStorageWithRedisCache
,注意该类库采用了StackExchange.Redis.Extensions.Core
,你可以在nuget
上下载该类库,如果你对默认的Redis
键值生成方式不满意,你也可以通过重写GetKey
方法来指定新的键值生成方式。当然,因为实际存储在Redis
中的数据都只是一些简单数据,并不需要额外的序列化过程,实际你也可以直接使用StackExchange.Redis
。
/// <summary> /// 校验码信息存储到Redis /// </summary> public class CodeStorageWithRedisCache : ICodeStorage { private readonly IRedisCacheClient _client; private const string CodeValueHashKey = "Code"; private const string CodeErrorHashKey = "Error"; private const string PeriodHashKey = "Period"; /// <summary> /// Code缓存Key值前缀 /// </summary> public string CodeKeyPrefix { get; set; } = "CC"; /// <summary> /// Period缓存Key值前缀 /// </summary> public string PeriodKeyPrefix { get; set; } = "CCT"; /// <summary> /// 缓存写入Redis哪个库 /// </summary> public int DbNumber { get; set; } = 8; /// <summary> /// 基于RedisCacheClient的构造函数 /// </summary> /// <param name="client"></param> public CodeStorageWithRedisCache(IRedisCacheClient client) { this._client = client; } /// <summary> /// 获取校验码周期内已发送次数,如果周期已到或未发送过任何验证码,则返回0 /// </summary> /// <param name="receiver"></param> /// <param name="bizFlag"></param> /// <returns></returns> public async Task<int> GetAreadySendTimes(string receiver, string bizFlag) { var db = this.GetDatabase(); var key = this.GetPeriodKey(receiver, bizFlag); var times = await db.HashGetAsync<int>(key, PeriodHashKey).ConfigureAwait(false); #if DEBUG Console.WriteLine("Method:{0} Result:{1}", nameof(GetAreadySendTimes), times); #endif return times; } /// <summary> /// 获取校验码及已尝试错误次数,如果校验码不存在或已过期,则返回null /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <returns></returns> public async Task<Tuple<string, int>> GetEffectiveCode(string receiver, string bizFlag) { var db = this.GetDatabase(); var key = this.GetCodeKey(receiver, bizFlag); if (await db.ExistsAsync(key).ConfigureAwait(false)) { var code = await db.HashGetAsync<string>(key, CodeValueHashKey).ConfigureAwait(false); var errors = await db.HashGetAsync<int>(key, CodeErrorHashKey).ConfigureAwait(false); #if DEBUG Console.WriteLine("Method:{0} Result: Code {1} Errors {2} ", nameof(GetEffectiveCode), code, errors); #endif return Tuple.Create(code, errors); } return null; } /// <summary> /// 校验码错误次数+1,如果校验码已过期,则不进行任何操作 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <returns></returns> public async Task IncreaseCodeErrors(string receiver, string bizFlag) { var db = this.GetDatabase(); var key = this.GetCodeKey(receiver, bizFlag); if (await db.ExistsAsync(key).ConfigureAwait(false)) { var errors = await db.HashGetAsync<int>(key, CodeErrorHashKey).ConfigureAwait(false); await db.HashSetAsync(key, CodeErrorHashKey, errors + 1).ConfigureAwait(false); } } /// <summary> /// 校验码周期内发送次数+1,如果周期已到,则不进行任何操作 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <returns></returns> public async Task IncreaseSendTimes(string receiver, string bizFlag) { var db = this.GetDatabase(); var key = this.GetPeriodKey(receiver, bizFlag); if (await db.ExistsAsync(key).ConfigureAwait(false)) { var times = await db.HashGetAsync<int>(key, PeriodHashKey).ConfigureAwait(false); await db.HashSetAsync(key, PeriodHashKey, times + 1).ConfigureAwait(false); } } /// <summary> /// 将校验码进行持久化,如果接收方和业务标志组合已经存在,则进行覆盖 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="code">校验码</param> /// <param name="effectiveTime">校验码有效时间范围</param> /// <returns></returns> public async Task<bool> SetCode(string receiver, string bizFlag, string code, TimeSpan effectiveTime) { var db = this.GetDatabase(); var key = this.GetCodeKey(receiver, bizFlag); await db.RemoveAsync(key).ConfigureAwait(false); var ret = await db.HashSetAsync(key, CodeValueHashKey, code).ConfigureAwait(false) && await db.HashSetAsync(key, CodeErrorHashKey, 0).ConfigureAwait(false) && await db.UpdateExpiryAsync(key, effectiveTime); #if DEBUG Console.WriteLine("Method:{0} Result:{1}", nameof(SetCode), ret); #endif return ret; } /// <summary> /// 校验码发送次数周期持久化,如果接收方和业务标志组合已经存在,则进行覆盖 /// </summary> /// <param name="receiver">接收方</param> /// <param name="bizFlag">业务标志</param> /// <param name="period">周期时间范围</param> /// <returns></returns> public async Task<bool> SetPeriod(string receiver, string bizFlag, TimeSpan? period) { var db = this.GetDatabase(); var key = this.GetPeriodKey(receiver, bizFlag); await db.RemoveAsync(key).ConfigureAwait(false); var ret = await db.HashSetAsync(key, PeriodHashKey, 1).ConfigureAwait(false); if (period.HasValue) { ret = ret && await db.UpdateExpiryAsync(key, period.Value); } #if DEBUG Console.WriteLine("Method:{0} Result:{1}", nameof(SetPeriod), ret); #endif return ret; } /// <summary> /// 组织Redis键值 /// </summary> /// <param name="receiver"></param> /// <param name="bizFlag"></param> /// <param name="prefix"></param> /// <returns></returns> protected virtual string GetKey(string receiver, string bizFlag, string prefix) { return string.Format("{0}:{1}:{2}", prefix, bizFlag, receiver); } private string GetPeriodKey(string receiver, string bizFlag) { return this.GetKey(receiver, bizFlag, this.PeriodKeyPrefix); } private string GetCodeKey(string receiver, string bizFlag) { return this.GetKey(receiver, bizFlag, this.CodeKeyPrefix); } private IRedisDatabase GetDatabase() { return this._client.GetDb(this.DbNumber); } }
最后,就是不可能通用的实现了,对于ICodeSender
而言,先不说发送方式不同,就算相同,比如都是手机,那也还有不同的短信供应商,所以此处必须要使用者按自己的实际业务来实现,为了方便举例,这里我写了一个在控制台输出验证码内容的实现。
ConsoleSender
,注意IsSupport
在此处输出true
,代表支持任意receiver
/// <summary> /// 在控制台输出校验码 /// </summary> public class ConsoleSender : ICodeSender { public ConsoleSender(IContentFormatter formatter) { this.Formatter = formatter ?? throw new ArgumentNullException(nameof(formatter)); } public IContentFormatter Formatter { get; } public bool IsSupport(string receiver) => true; public Task<bool> Send(string receiver, string bizFlag, string code, TimeSpan effectiveTime) { var content = this.Formatter.GetContent(receiver, bizFlag, code, effectiveTime); Console.WriteLine("发送内容:{0}", content); return Task.FromResult(true); } }
最后则是如何使用的代码例子,注意此处Redis
序列化方式采用了StackExchange.Redis.Extensions.Newtonsoft
,你可以根据实际需要采用其它序列化方式,比如StackExchange.Redis.Extensions.Protobuf
等,你同样可以在nuget
上下载到这些类库。
static void CheckCodeHelperDemo() { var redisConfig = new RedisConfiguration { Hosts = new RedisHost[] { new RedisHost{ Host="127.0.0.1", Port=6379 } } }; var bizFlag = "forgetPassword"; var receiver = "Receiver"; var effectiveTime = TimeSpan.FromMinutes(1); var redisManager = new RedisCacheConnectionPoolManager(redisConfig); var redisClient = new RedisCacheClient(redisManager, new NewtonsoftSerializer(), redisConfig);//new ProtobufSerializer(); var storage = new CodeStorageWithRedisCache(redisClient); var simpleFormatter = new ContentFormatter( (r, b, c, e) => $"{r}您好,您的忘记密码验证码为{c},有效期为{(int)e.TotalSeconds}秒."); var formatter = new ComplexContentFormatter(); formatter.SetFormatter(bizFlag, simpleFormatter); var sender = new ConsoleSender(formatter); //如果就一个业务场景,也可以直接用simpleFormatter //var tmp = storage.SetPeriod(receiver, bizFlag, TimeSpan.FromMinutes(20)).Result; var helper = new CodeHelper(sender, storage); var code = CodeHelper.GetRandomNumber(); var sendResult = helper.SendCode(receiver, bizFlag, code, effectiveTime, new PeriodLimit { MaxLimit = 5, Period = TimeSpan.FromMinutes(20) }).Result; Console.WriteLine("发送结果:{0}", sendResult); if (sendResult == SendResult.Success) { Console.WriteLine("*****************************"); while (true) { Console.WriteLine("请输入校验码:"); var vCode = Console.ReadLine(); var vResult = helper.VerifyCode(receiver, bizFlag, vCode, 3).Result; Console.WriteLine("校验码 {0} 校验结果:{1}", vCode, vResult); if (vResult != VerificationResult.VerificationFailed) { break; } } } redisManager.Dispose(); }
最后则是不同测试场景的一些截图
验证码校验失败达到允许次数上限
校验码已过期
校验码验证成功
校验码周期内允许的发送次数已达到上限
最后,上述完整的代码可见github。