asp.Net Core 改变响应值的几种方法

1.中间件

using Microsoft.AspNetCore.Mvc;
using System.Text;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers();
var app = builder.Build();
app.UseMiddleware<ReplaceMiddleware>();
app.MapControllers();
app.Run();

public class HomeController : Controller
{
    [HttpGet("/")]
    public IActionResult Index() => Content("XXX%%%%%%%%%%%%%%");
}

public class ReplaceMiddleware
{
    private readonly RequestDelegate _next;

    public ReplaceMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        string content;
        var originalBody = context.Response.Body;
        using (var memStream = new MemoryStream())
        {
            context.Response.Body = memStream;
            await _next(context);

            memStream.Position = 0;
            string responseBody = await new StreamReader(memStream).ReadToEndAsync();
            content = responseBody.Replace("XXX", "YYY");

            context.Response.Body = originalBody;
            await context.Response.Body.WriteAsync(Encoding.UTF8.GetBytes(content));
        }
    }
}

2.ResultFilter

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using System.Text;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers();
var app = builder.Build();
//app.UseMiddleware<ReplaceMiddleware>();
app.MapControllers();
app.Run();

public class HomeController : Controller
{
    [HttpGet("/")]
    [ReplaceFilter]
    public IActionResult Index() => Content("XXX%%%%%%%%%%%%%%");
}

public class ReplaceFilterAttribute : ResultFilterAttribute
{
    public override async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
    {
        string content;
        var originalBody = context.HttpContext.Response.Body;
        using (var memStream = new MemoryStream())
        {
            context.HttpContext.Response.Body = memStream;
            await base.OnResultExecutionAsync(context, next);

            memStream.Position = 0;
            string responseBody = await new StreamReader(memStream).ReadToEndAsync();
            content = responseBody.Replace("XXX", "YYY");

            context.HttpContext.Response.Body = originalBody;
            await context.HttpContext.Response.Body.WriteAsync(Encoding.UTF8.GetBytes(content));
        }
    }
}

3.ActionFilter

public class ReplaceFilterAttribute : ActionFilterAttribute
{
    public override async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
    {
        string content;
        var originalBody = context.HttpContext.Response.Body;
        using (var memStream = new MemoryStream())
        {
            context.HttpContext.Response.Body = memStream;
            await base.OnResultExecutionAsync(context, next);

            memStream.Position = 0;
            string responseBody = await new StreamReader(memStream).ReadToEndAsync();
            content = responseBody.Replace("XXX", "YYY");

            context.HttpContext.Response.Body = originalBody;
            await context.HttpContext.Response.Body.WriteAsync(Encoding.UTF8.GetBytes(content));
        }
    }
}