Simplify 404 example using `or`

examples/global-404-handler/src/main.rs

@@ -5,14 +5,11 @@
 //! ```
 
 use axum::{
-    body::{box_body, Body, BoxBody},
-    handler::get,
-    http::{Response, StatusCode},
+    handler::{get, Handler},
     response::Html,
     Router,
 };
 use std::net::SocketAddr;
-use tower::util::MapResponseLayer;
 
 #[tokio::main]
 async fn main() {
@@ -23,10 +20,10 @@ async fn main() {
     tracing_subscriber::fmt::init();
 
     // build our application with a route
-    let app = Router::new()
-        .route("/", get(handler))
-        // make sure this is added as the very last thing
-        .layer(MapResponseLayer::new(map_404));
+    let app = Router::new().route("/", get(handler));
+
+    // make sure this is added as the very last thing
+    let app = app.or(handler_404.into_service());
 
     // run it
     let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
@@ -41,15 +38,6 @@ async fn handler() -> Html<&'static str> {
     Html("<h1>Hello, World!</h1>")
 }
 
-fn map_404(response: Response<BoxBody>) -> Response<BoxBody> {
-    if response.status() == StatusCode::NOT_FOUND
-        || response.status() == StatusCode::METHOD_NOT_ALLOWED
-    {
-        return Response::builder()
-            .status(StatusCode::NOT_FOUND)
-            .body(box_body(Body::from("nothing to see here")))
-            .unwrap();
-    }
-
-    response
+async fn handler_404() -> &'static str {
+    "nothing to see here"
 }