Cargo.toml 依赖如下：

actix-web = "4.5.1"
actix-session = { version = "0.9.0", features = ["redis-actor-session"] }

main.rs 代码如下：

use actix_session::{storage::RedisActorSessionStore, Session, SessionExt, SessionMiddleware};
use actix_web::{cookie::Key, dev::Service, web, App, HttpResponse, HttpServer};

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    let secret_key = Key::generate();
    HttpServer::new(move || {
        App::new()
            .wrap(
                SessionMiddleware::builder(
                    RedisActorSessionStore::new("127.0.0.1:6379"),
                    secret_key.clone(),
                )
                .build(),
            )
            .wrap_fn(|req, srv| {
                if let Ok(Some(user)) = req.get_session().get::<i32>("user") {
                    println!("middleware: {}", user);
                } else {
                    println!("middleware: {}", 0);
                }
                srv.call(req)
            })
            .route(
                "/set",
                web::to(|session: Session| {
                    let _ = session.insert("user", 1);
                    HttpResponse::Ok()
                }),
            )
            .route(
                "/get",
                web::to(|session: Session| {
                    if let Ok(Some(user)) = session.get::<i32>("user") {
                        println!("get: {}", user);
                    } else {
                        println!("get: {}", 0);
                    }
                    HttpResponse::Ok()
                }),
            )
    })
    .bind(("0.0.0.0", 8000))?
    .run()
    .await
}

先执行 http://127.0.0.1:8000/set 设置 session 值

再执行 http://127.0.0.1:8000/get 打印 session 值

路由 “/get” 中可以获取 session 值，但是 wrap_fn(middleware) 中无法获取 session 值，出题出在哪？请高手给指点下。

感谢 liusen-adalab 的帮忙，原来是因为两个中间件位置反了，已经把正确的代码也加上了，方便和我一样遇到这个问题的人

main.rs 正确代码如下：

use actix_session::{storage::RedisActorSessionStore, Session, SessionExt, SessionMiddleware};
use actix_web::{cookie::Key, dev::Service, web, App, HttpResponse, HttpServer};

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    let secret_key = Key::generate();
    HttpServer::new(move || {
        App::new()
            .wrap_fn(|req, srv| {
                if let Ok(Some(user)) = req.get_session().get::<i32>("user") {
                    println!("middleware: {}", user);
                } else {
                    println!("middleware: {}", 0);
                }
                srv.call(req)
            })
            .wrap(
                SessionMiddleware::builder(
                    RedisActorSessionStore::new("127.0.0.1:6379"),
                    secret_key.clone(),
                )
                .build(),
            )
            .route(
                "/set",
                web::to(|session: Session| {
                    let _ = session.insert("user", 1);
                    HttpResponse::Ok()
                }),
            )
            .route(
                "/get",
                web::to(|session: Session| {
                    if let Ok(Some(user)) = session.get::<i32>("user") {
                        println!("get: {}", user);
                    } else {
                        println!("get: {}", 0);
                    }
                    HttpResponse::Ok()
                }),
            )
    })
    .bind(("0.0.0.0", 8000))?
    .run()
    .await
}