.Net Core Aop之IActionFilter

一、简介

在.net core 中Filter分为以下六大类：

1、AuthorizeAttribute（权限验证）

2、IResourceFilter（资源缓存）

3、IActionFilter（执行方法前后的记录）

4、IResultFilter（结果生成前后扩展）

5、IAlwaysRun（响应结果的补充）

6、IExceptionFilter（异常处理）

 二、IActionFilter（同步）

1、定义Filter

public class CustomerActionFilterAttribute : Attribute, IActionFilter
{
/// <summary>
/// 在XXAction执行之前
/// </summary>
/// <param name="context"></param>
public void OnActionExecuting(ActionExecutingContext context)
{
Console.WriteLine("CustomerActionFilterAttribute.OnActionExecuting");
}

/// <summary>
/// 在XXAction执行之后
/// </summary>
/// <param name="context"></param>
public void OnActionExecuted(ActionExecutedContext context)
{
Console.WriteLine("CustomerActionFilterAttribute.OnActionExecuted");
}

}

2、使用Filter

public class Home1Controller : Controller
{
private readonly ILogger<HomeController> _logger;

public Home1Controller(ILogger<HomeController> logger)
{
_logger = logger;
Console.WriteLine($"执行 {this.GetType().Name} 构造函数");
}

[CustomerActionFilter]
public IActionResult Index()
{
Console.WriteLine($"执行 Index 方法");
return View();
}
}

 3、扩展记录日志

public class CustomerActionFilterAttribute : Attribute, IActionFilter
{

private readonly ILogger<CustomerActionFilterAttribute> _logger;

public CustomerActionFilterAttribute(ILogger<CustomerActionFilterAttribute> logger)
{
_logger = logger;
}
/// <summary>
/// 在XXAction执行之前
/// </summary>
/// <param name="context"></param>
public void OnActionExecuting(ActionExecutingContext context)
{
var para = context.HttpContext.Request.QueryString.Value;
var controllerName = context.ActionDescriptor.RouteValues["controller"];
var actionName = context.ActionDescriptor.RouteValues["action"];

_logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求参数是{JsonConvert.SerializeObject(para)}");

}

/// <summary>
/// 在XXAction执行之后
/// </summary>
/// <param name="context"></param>
public void OnActionExecuted(ActionExecutedContext context)
{
var para = context.Result;
var controllerName = context.ActionDescriptor.RouteValues["controller"];
var actionName = context.ActionDescriptor.RouteValues["action"];
_logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求结果是{JsonConvert.SerializeObject(para)}");

}
}

public class Home1Controller : Controller
{
private readonly ILogger<HomeController> _logger;

public Home1Controller(ILogger<HomeController> logger)
{
_logger = logger;
Console.WriteLine($"执行 {this.GetType().Name} 构造函数");
}

[TypeFilter(typeof(CustomerActionFilterAttribute))]
public IActionResult Index(int id)
{
Console.WriteLine($"执行 Index 方法");
ViewBag.Data = new { name = "11111" };
return View();
}
}

 三、IAsyncActionFilter（异步）

public class CustomerAsyncActionFilterAttribute : Attribute, IAsyncActionFilter
{

private readonly ILogger<CustomerAsyncActionFilterAttribute> _logger;

public CustomerAsyncActionFilterAttribute(ILogger<CustomerAsyncActionFilterAttribute> logger)
{
_logger = logger;
}
public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
{

var para = context.HttpContext.Request.QueryString.Value;
var controllerName = context.ActionDescriptor.RouteValues["controller"];
var actionName = context.ActionDescriptor.RouteValues["action"];

_logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求参数是{JsonConvert.SerializeObject(para)}");

var excuteContext = await next.Invoke(); // 这句话就是去执行Action

_logger.LogInformation($"当前请求的控制器是{controllerName},方法名{actionName},请求结果是{JsonConvert.SerializeObject(excuteContext.Result)}");

}
}

public class Home1Controller : Controller
{
private readonly ILogger<HomeController> _logger;

public Home1Controller(ILogger<HomeController> logger)
{
_logger = logger;
Console.WriteLine($"执行 {this.GetType().Name} 构造函数");
}

//[TypeFilter(typeof(CustomerActionFilterAttribute))]
[TypeFilter(typeof(CustomerAsyncActionFilterAttribute))]
public IActionResult Index(int id)
{
Console.WriteLine($"执行 Index 方法");
ViewBag.Data = new { name = "11111" };
return View();
}
}

四、总结

作用：该Filter可以记录Action执行前后的参数和结果

执行顺序：
1、执行控制器的构造函数
2、执行CustomerActionFilterAttribute.OnActionExecuting
3、执行Action方法
4、执行CustomerActionFilterAttribute.OnActionExecuted