.Net Core3.0 WebApi 十四：基于AOP的切面redis缓存

.Net Core3.0 WebApi 目录

什么是AOP

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面向切面编程AOP

更新Redis缓存接口

在之前的redis缓存博客中我们定义了redis操作接口和实现，在实际项目开发中，我又对它进行了修改，主要是增加了异步和批量删除的接口。修改Infrastructure下的Redis文件夹的IRedisCacheManager文件和RedisCacheManager增加以下接口和方法。

IRedisCacheManager：

//获取 Reids 缓存值
Task<string> GetValueAsync(string key);

//获取值，并序列化
Task<TEntity> GetAsync<TEntity>(string key);

//保存
Task SetAsync(string key, object value, TimeSpan cacheTime);

//判断是否存在
Task<bool> GetAsync(string key);

//移除某一个缓存值
Task RemoveAsync(string key);

//根据关键字移除
Task RemoveByKey(string key);

//全部清除
Task ClearAsync();

RedisCacheManager：

 public async Task ClearAsync()
 {
     foreach (var endPoint in this.GetRedisConnection().GetEndPoints())
     {
         var server = this.GetRedisConnection().GetServer(endPoint);
         foreach (var key in server.Keys())
         {
             await redisConnection.GetDatabase().KeyDeleteAsync(key);
         }
     }
 }

 public async Task<bool> GetAsync(string key)
 {
     return await redisConnection.GetDatabase().KeyExistsAsync(key);
 }

 public async Task<string> GetValueAsync(string key)
 {
     return await redisConnection.GetDatabase().StringGetAsync(key);
 }

 public async Task<TEntity> GetAsync<TEntity>(string key)
 {
     var value = await redisConnection.GetDatabase().StringGetAsync(key);
     if (value.HasValue)
     {
         //需要用的反序列化，将Redis存储的Byte[]，进行反序列化
         return SerializeHelper.Deserialize<TEntity>(value);
     }
     else
     {
         return default;
     }
 }

 public async Task RemoveAsync(string key)
 {
     await redisConnection.GetDatabase().KeyDeleteAsync(key);
 }

 public async Task RemoveByKey(string key)
 {
     var redisResult = await redisConnection.GetDatabase().ScriptEvaluateAsync(LuaScript.Prepare(
         //Redis的keys模糊查询：
         " local res = redis.call('KEYS', @keypattern) " +
         " return res "), new { @keypattern = key });

     if (!redisResult.IsNull)
     {
         var keys = (string[])redisResult;
         foreach (var k in keys)
             redisConnection.GetDatabase().KeyDelete(k);

     }
 }

 public async Task SetAsync(string key, object value, TimeSpan cacheTime)
 {
     if (value != null)
     {
         //序列化，将object值生成RedisValue
         await redisConnection.GetDatabase().StringSetAsync(key, SerializeHelper.Serialize(value), cacheTime);
     }
 }

 public async Task<bool> SetValueAsync(string key, byte[] value)
 {
     return await redisConnection.GetDatabase().StringSetAsync(key, value, TimeSpan.FromSeconds(120));
 }

定义缓存特性

Infrastructure层新增Attributes文件夹，并新建CachingAttribute来定义我们的redis缓存特性，有了这个特性，我们就可以控制方法是否需要缓存到redis。

namespace WebApi.Core.Infrastructure.Attributes
{
    /// <summary>
    /// 这个Attribute就是使用时候的验证，把它添加到要缓存数据的方法中，即可完成缓存的操作。
    /// </summary>
    [AttributeUsage(AttributeTargets.Method, Inherited = true)]
    public class CachingAttribute : Attribute
    {
        //过期时间
        public int AbsoluteExpiration { get; set; }
        /// <summary>
        /// 自定义key
        /// </summary>
        public string CustomKeyValue { get; set; }
        /// <summary>
        /// 是否删除
        /// </summary>
        public bool IsDelete { get; set; } = false;
    }
}

定义Redis切面拦截器

在主工程WebApi.Core.Api新加AOP文件夹，新建CacheAOPbase和RedisCacheAOP文件

namespace WebApi.Core.Api.AOP
{
    public abstract class CacheAOPbase : IInterceptor
    {
        /// <summary>
        /// AOP的拦截方法
        /// </summary>
        /// <param name="invocation"></param>
        public abstract void Intercept(IInvocation invocation);

        /// <summary>
        /// 自定义缓存的key
        /// </summary>
        /// <param name="invocation"></param>
        /// <returns></returns>
        protected string CustomCacheKey(IInvocation invocation)
        {
            var typeName = invocation.TargetType.Name;
            var methodName = invocation.Method.Name;
            var methodArguments = invocation.Arguments.Select(GetArgumentValue).Take(3).ToList();//获取参数列表，最多三个

            string key = $"{typeName}:{methodName}:";
            foreach (var param in methodArguments)
            {
                key = $"{key}{param}:";
            }

            return key.TrimEnd(':');
        }

        /// <summary>
        /// object 转 string
        /// </summary>
        /// <param name="arg"></param>
        /// <returns></returns>
        protected static string GetArgumentValue(object arg)
        {
            if (arg is DateTime || arg is DateTime?)
                return ((DateTime)arg).ToString("yyyyMMddHHmmss");

            if (arg is string || arg is ValueType || arg is Nullable)
                return arg.ToString();

            if (arg != null)
            {
                if (arg is Expression)
                {
                    var obj = arg as Expression;
                    var result = Resolve(obj);
                    return Infrastructure.Helpers.MD5Helper.MD5Encrypt16(result);
                }
                else if (arg.GetType().IsClass)
                {
                    return Infrastructure.Helpers.MD5Helper.MD5Encrypt16(Newtonsoft.Json.JsonConvert.SerializeObject(arg));
                }
            }
            return string.Empty;
        }

        private static string Resolve(Expression expression)
        {
            if (expression is LambdaExpression)
            {
                LambdaExpression lambda = expression as LambdaExpression;
                expression = lambda.Body;
                return Resolve(expression);
            }
            if (expression is BinaryExpression)
            {
                BinaryExpression binary = expression as BinaryExpression;
                if (binary.Left is MemberExpression && binary.Right is ConstantExpression)//解析x=>x.Name=="123" x.Age==123这类
                    return ResolveFunc(binary.Left, binary.Right, binary.NodeType);
                if (binary.Left is MethodCallExpression && binary.Right is ConstantExpression)//解析x=>x.Name.Contains("xxx")==false这类的
                {
                    object value = (binary.Right as ConstantExpression).Value;
                    return ResolveLinqToObject(binary.Left, value, binary.NodeType);
                }
                if ((binary.Left is MemberExpression && binary.Right is MemberExpression)
                    || (binary.Left is MemberExpression && binary.Right is UnaryExpression))//解析x=>x.Date==DateTime.Now这种
                {
                    LambdaExpression lambda = Expression.Lambda(binary.Right);
                    Delegate fn = lambda.Compile();
                    ConstantExpression value = Expression.Constant(fn.DynamicInvoke(null), binary.Right.Type);
                    return ResolveFunc(binary.Left, value, binary.NodeType);
                }
            }
            if (expression is UnaryExpression)
            {
                UnaryExpression unary = expression as UnaryExpression;
                if (unary.Operand is MethodCallExpression)//解析!x=>x.Name.Contains("xxx")或!array.Contains(x.Name)这类
                    return ResolveLinqToObject(unary.Operand, false);
                if (unary.Operand is MemberExpression && unary.NodeType == ExpressionType.Not)//解析x=>!x.isDeletion这样的 
                {
                    ConstantExpression constant = Expression.Constant(false);
                    return ResolveFunc(unary.Operand, constant, ExpressionType.Equal);
                }
            }
            if (expression is MemberExpression && expression.NodeType == ExpressionType.MemberAccess)//解析x=>x.isDeletion这样的 
            {
                MemberExpression member = expression as MemberExpression;
                ConstantExpression constant = Expression.Constant(true);
                return ResolveFunc(member, constant, ExpressionType.Equal);
            }
            if (expression is MethodCallExpression)//x=>x.Name.Contains("xxx")或array.Contains(x.Name)这类
            {
                MethodCallExpression methodcall = expression as MethodCallExpression;
                return ResolveLinqToObject(methodcall, true);
            }
            //已经修改过代码body应该不会是null值了
            if (!(expression is BinaryExpression body))
                return string.Empty;
            var Operator = GetOperator(body.NodeType);
            var Left = Resolve(body.Left);
            var Right = Resolve(body.Right);
            string Result = string.Format("({0} {1} {2})", Left, Operator, Right);
            return Result;
        }

        private static string GetOperator(ExpressionType expressiontype)
        {
            return expressiontype switch
            {
                ExpressionType.And => "and",
                ExpressionType.AndAlso => "and",
                ExpressionType.Or => "or",
                ExpressionType.OrElse => "or",
                ExpressionType.Equal => "=",
                ExpressionType.NotEqual => "<>",
                ExpressionType.LessThan => "<",
                ExpressionType.LessThanOrEqual => "<=",
                ExpressionType.GreaterThan => ">",
                ExpressionType.GreaterThanOrEqual => ">=",
                _ => throw new Exception(string.Format("不支持{0}此种运算符查找！" + expressiontype)),
            };
        }

        private static string ResolveFunc(Expression left, Expression right, ExpressionType expressiontype)
        {
            var Name = (left as MemberExpression).Member.Name;
            var Value = (right as ConstantExpression).Value;
            var Operator = GetOperator(expressiontype);
            return Name + Operator + Value ?? "null";
        }

        private static string ResolveLinqToObject(Expression expression, object value, ExpressionType? expressiontype = null)
        {
            var MethodCall = expression as MethodCallExpression;
            var MethodName = MethodCall.Method.Name;
            switch (MethodName)
            {
                case "Contains":
                    if (MethodCall.Object != null)
                        return Like(MethodCall);
                    return In(MethodCall, value);
                case "Count":
                    return Len(MethodCall, value, expressiontype.Value);
                case "LongCount":
                    return Len(MethodCall, value, expressiontype.Value);
                default:
                    throw new Exception(string.Format("不支持{0}方法的查找！", MethodName));
            }
        }

        private static string In(MethodCallExpression expression, object isTrue)
        {
            var Argument1 = (expression.Arguments[0] as MemberExpression).Expression as ConstantExpression;
            var Argument2 = expression.Arguments[1] as MemberExpression;
            var Field_Array = Argument1.Value.GetType().GetFields().First();
            object[] Array = Field_Array.GetValue(Argument1.Value) as object[];
            List<string> SetInPara = new List<string>();
            for (int i = 0; i < Array.Length; i++)
            {

                string Value = Array[i].ToString();
                SetInPara.Add(Value);
            }
            string Name = Argument2.Member.Name;
            string Operator = Convert.ToBoolean(isTrue) ? "in" : " not in";
            string CompName = string.Join(",", SetInPara);
            string Result = string.Format("{0} {1} ({2})", Name, Operator, CompName);
            return Result;
        }
        private static string Like(MethodCallExpression expression)
        {

            var Temp = expression.Arguments[0];
            LambdaExpression lambda = Expression.Lambda(Temp);
            Delegate fn = lambda.Compile();
            var tempValue = Expression.Constant(fn.DynamicInvoke(null), Temp.Type);
            string Value = string.Format("%{0}%", tempValue);
            string Name = (expression.Object as MemberExpression).Member.Name;
            string Result = string.Format("{0} like {1}", Name, Value);
            return Result;
        }


        private static string Len(MethodCallExpression expression, object value, ExpressionType expressiontype)
        {
            object Name = (expression.Arguments[0] as MemberExpression).Member.Name;
            string Operator = GetOperator(expressiontype);
            string Result = string.Format("len({0}){1}{2}", Name, Operator, value.ToString());
            return Result;
        }

    }
}

namespace WebApi.Core.Api.AOP
{
    /// <summary>
    /// 面向切面的缓存使用
    /// </summary>
    public class RedisCacheAOP : CacheAOPbase
    {
        //通过注入的方式，把缓存操作接口通过构造函数注入
        private readonly IRedisCacheManager _cache;
        public RedisCacheAOP(IRedisCacheManager cache)
        {
            _cache = cache;
        }

        //Intercept方法是拦截的关键所在，也是IInterceptor接口中的唯一定义
        //代码已经合并 ，学习pr流程
        public override void Intercept(IInvocation invocation)
        {
            var method = invocation.MethodInvocationTarget ?? invocation.Method;
            if (method.ReturnType == typeof(void) || method.ReturnType == typeof(Task))
            {
                invocation.Proceed();
                return;
            }
            //对当前方法的特性验证

            if (method.GetCustomAttributes(true).FirstOrDefault(x => x.GetType() == typeof(CachingAttribute)) is CachingAttribute qCachingAttribute)
            {
                //获取自定义缓存键
                var cacheKey = qCachingAttribute.CustomKeyValue ?? CustomCacheKey(invocation);
                //注意是 string 类型，方法GetValue
                var cacheValue = _cache.GetValue(cacheKey);
                if (cacheValue != null)
                {
                    if (qCachingAttribute.IsDelete)
                    {
                        //删除Redis里面的数据
                        _cache.Remove(cacheKey);
                    }
                    else
                    {
                        //将当前获取到的缓存值，赋值给当前执行方法
                        Type returnType;
                        if (typeof(Task).IsAssignableFrom(method.ReturnType))
                        {
                            returnType = method.ReturnType.GenericTypeArguments.FirstOrDefault();
                        }
                        else
                        {
                            returnType = method.ReturnType;
                        }
                        dynamic _result = Newtonsoft.Json.JsonConvert.DeserializeObject(cacheValue, returnType);
                        invocation.ReturnValue = (typeof(Task).IsAssignableFrom(method.ReturnType)) ? Task.FromResult(_result) : _result;
                        return;
                    }
                }
                //去执行当前的方法
                invocation.Proceed();

                //存入缓存
                if (!string.IsNullOrWhiteSpace(cacheKey) && qCachingAttribute.IsDelete == false)
                {
                    object response;

                    //Type type = invocation.ReturnValue?.GetType();
                    var type = invocation.Method.ReturnType;
                    if (typeof(Task).IsAssignableFrom(type))
                    {
                        var resultProperty = type.GetProperty("Result");
                        response = resultProperty.GetValue(invocation.ReturnValue);
                    }
                    else
                    {
                        response = invocation.ReturnValue;
                    }
                    if (response == null) response = string.Empty;

                    _cache.Set(cacheKey, response, TimeSpan.FromMinutes(qCachingAttribute.AbsoluteExpiration));
                }
            }
            else
            {
                invocation.Proceed();//直接执行被拦截方法
            }
        }
    }
}

注入到服务到 Autofac

Setup的AutofacModuleRegister文件注入redisaop缓存

测试APO缓存

User控制器新建AopTest接口

/// <summary>
/// 测试aop缓存redis
/// </summary>
/// <returns></returns>
[HttpGet]
public async Task<IActionResult> AopTest(int id)
{
    var response = await _userService.GetUserDetails(id);
    return Ok(response);
}

userService的GetUserDetails方法上方标注特性

 [Caching(AbsoluteExpiration = 1)]
 public async Task<UserResponse> GetUserDetails(int id)
 {
     //var userinfo = await userDal.QueryByID(id);
     var userinfo = new UserNew
     {
         UserId = id,
         UserName = "bingle",
         Age = 18
     };

     if (userinfo != null)
     {
         //UserResponse model = new UserResponse()
         //{
         //    UserId = userinfo.UserId,
         //    UserName = userinfo.UserName,
         //    Address = "xx市xx区xx小区",
         //    Age = userinfo.Age,
         //    Birthday = "1996-06-26",
         //    Phone = "13888888888"

         //};
         UserResponse model = iMapper.Map<UserResponse>(userinfo);
         model.Address = "xx市xx区xx小区";
         model.Birthday = "1996-06-26";
         model.Phone = "13888888888";
         return model;
     }
     else
     {
         return null;
     }
 }

运行，调试接口

 断点达到的时候可以看到没有数据

开始从数据库中查询：

  再次执行Aoptest接口，可以看到数据已经被缓存了。这样我们就实现了基于AOP的缓存