Add 404 page example (#97)

examples/404.rs

@@ -0,0 +1,46 @@
+//! Run with
+//!
+//! ```not_rust
+//! cargo run --example 404
+//! ```
+
+use axum::{
+    body::{box_body, Body, BoxBody},
+    prelude::*,
+};
+use http::{Response, StatusCode};
+use std::net::SocketAddr;
+use tower::util::MapResponseLayer;
+
+#[tokio::main]
+async fn main() {
+    tracing_subscriber::fmt::init();
+
+    // build our application with a route
+    let app = route("/", get(handler))
+        // make sure this is added as the very last thing
+        .layer(MapResponseLayer::new(map_404));
+
+    // run it
+    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
+    tracing::debug!("listening on {}", addr);
+    hyper::Server::bind(&addr)
+        .serve(app.into_make_service())
+        .await
+        .unwrap();
+}
+
+async fn handler() -> response::Html<&'static str> {
+    response::Html("<h1>Hello, World!</h1>")
+}
+
+fn map_404(response: Response<BoxBody>) -> Response<BoxBody> {
+    if response.status() != StatusCode::NOT_FOUND {
+        return response;
+    }
+
+    Response::builder()
+        .status(StatusCode::NOT_FOUND)
+        .body(box_body(Body::from("nothing to see here")))
+        .unwrap()
+}

examples/README.md

@@ -16,3 +16,4 @@
 - [`sessions`](../examples/sessions.rs) - Sessions and cookies using [`async-session`](https://crates.io/crates/async-session).
 - [`tls_rustls`](../examples/tls_rustls.rs) - TLS with [`tokio-rustls`](https://crates.io/crates/tokio-rustls).
 - [`chat`](../examples/chat.rs) - Chat application example.
+- [`404`](../examples/404.rs) - Custom 404 page.