update examples to v4 (#258)

examples/responder-trait/Cargo.toml

@@ -4,7 +4,7 @@ version = "1.0.0"
 edition = "2018"
 
 [dependencies]
-actix-web = "3"
+actix-web = "4"
 futures = "0.3.1"
 serde = "1.0"
 serde_json = "1.0"

examples/responder-trait/src/main.rs

@@ -1,6 +1,7 @@
 // <responder-trait>
-use actix_web::{Error, HttpRequest, HttpResponse, Responder};
-use futures::future::{ready, Ready};
+use actix_web::{
+    body::BoxBody, http::header::ContentType, HttpRequest, HttpResponse, Responder,
+};
 use serde::Serialize;
 
 #[derive(Serialize)]
@@ -10,16 +11,15 @@ struct MyObj {
 
 // Responder
 impl Responder for MyObj {
-    type Error = Error;
-    type Future = Ready<Result<HttpResponse, Error>>;
+    type Body = BoxBody;
 
-    fn respond_to(self, _req: &HttpRequest) -> Self::Future {
+    fn respond_to(self, _req: &HttpRequest) -> HttpResponse<Self::Body> {
         let body = serde_json::to_string(&self).unwrap();
 
         // Create response and set content type
-        ready(Ok(HttpResponse::Ok()
-            .content_type("application/json")
-            .body(body)))
+        HttpResponse::Ok()
+            .content_type(ContentType::json())
+            .body(body)
     }
 }
 
@@ -33,7 +33,7 @@ async fn main() -> std::io::Result<()> {
     use actix_web::{web, App, HttpServer};
 
     HttpServer::new(|| App::new().route("/", web::get().to(index)))
-        .bind("127.0.0.1:8080")?
+        .bind(("127.0.0.1", 8080))?
         .run()
         .await
 }