http4s中如何在授权路由中处理JSON？

在http4s中，我们可以使用JsonEntityDecoder和JsonEntityEncoder来处理JSON。在授权路由中，我们可以使用AuthedRoutes来对请求进行身份验证，并在请求和响应中使用这些解码器和编码器来处理JSON数据。

下面是一个示例代码：

import cats.effect.IO
import io.circe.generic.auto._
import org.http4s._
import org.http4s.circe._
import org.http4s.dsl.io._
import org.http4s.server.{AuthMiddleware, Router}
import org.http4s.server.middleware.authentication.{AuthedRoutes, BasicAuth, User}
import org.http4s.syntax.kleisli._

case class UserCredentials(username: String, password: String)

case class UserData(name: String, age: Int)

object AuthService {

  // This checks the username and password for validity
  def validateUser(userCreds: UserCredentials): IO[Option[User]] = {
    if (userCreds.username == "admin" && userCreds.password == "password") {
      IO(Some(User(userCreds.username)))
    } else {
      IO(None)
    }
  }

  // This handles the request once the user is authed
  def authedRoutes(user: User): AuthedRoutes[String, IO] = 
    AuthedRoutes.of {
      case GET -> Root / "data" as _ =>
        Ok(UserData("John", 30))
      case authReq @ POST -> Root / "data" as user =>
        authReq.req.decodeJson[UserData].flatMap { userData =>
          // Do something with the data
          Ok("Data received")
        }
    }

  // This is the middleware that handles authentication
  def authMiddleware: AuthMiddleware[IO, User] = {
    BasicAuth[IO, User]("realm", validateUser _, realmErrorHandler)
  }
  
  // This is the error handler for the authentication middleware
  private val realmErrorHandler: AuthedService[String, IO] = Kleisli(req => {
    val challenge = BasicAuth.challenge("realm", Some("Authentication failed, please try again."))
    OptionT.liftF(Unauthorized(challenge))
  })

  // This is the router that includes our authed routes and middleware