前言
Viz，是个基于RUst的，快速、健壮、灵活、轻量级的 Web 框架。
特点
- 安全，禁止不安全代码
- 轻量
- 简单 + 灵活的处理器和中间件
- 链式操作
- 强大的Routing路由
一、Hello Viz
1. 创建项目
正如学习编程语言一样，我们先从官方入门案例学起，首先我们创建一个新项目
cargo new viz_hello
然后使用vscode打开
2. 引入viz
在Cargo.toml中写入，如下图
tokio = { version = "1.20.1", features = ["full"] } viz = "0.3.1"
然后使用build来下载依赖
cargo build
安装完成
3. 运行Hello Viz
复制以下代码到main.rs，
use std::net::SocketAddr; use viz::{Request, Result, Router, Server, ServiceMaker}; async fn index(_: Request) -> Result<&'static str> { Ok("Hello Viz") } #[tokio::main] async fn main() -> Result<()> { let addr = SocketAddr::from(([127, 0, 0, 1], 3000)); println!("listening on {}", addr); let app = Router::new().get("/", index); if let Err(err) = Server::bind(&addr) .serve(ServiceMaker::from(app)) .await { println!("{}", err); } Ok(()) }
4. 运行结果
如果你以上步骤没有出错，那么在终端中运行
cargo run
效果如下图
最后一行的意思是正在监听本地的127.0.0.1的3000端口，说明程序没有出错
此时在浏览器打开网址
http://localhost:3000/
注意
localhost指向127.0.0.1
此时页面应该是这个样子的
二、Hello Viz代码详解
从整体上来看，这块代码主要分为3个部分，分别是导入组件，处理index请求和主程序
导入组件
首先导入了SocketAddr，用来表示socket地址，然后导入了Viz的一些组件
- Request 请求
- Result 响应
- Router 路由
- Server 服务器
- ServiceMaker 服务
处理请求
这里使用异步函数来实现index的处理，传入Request，这个过程系统会自动为我们处理。然后响应的是字符串类型，在函数体中返回了字符串“Hello Viz”
主函数
在Viz中，主函数也是异步函数，使用addr表示本地地址和监听的端口，然后挂载Router，使与index处理器相联系，再开启服务器。
三、常见用法
简单的处理程序
async fn index(_: Request) -> Result<Response> { Ok(Response::text("Hello, World!")) } async fn about(_: Request) -> Result<&'static str> { Ok("About Me!") } async fn not_found(_: Request) -> Result<impl IntoResponse> { Ok("Not Found!") }
实现处理程序特质
#[derive(Clone)] struct MyHandler { code: Arc<AtomicUsize>, } #[async_trait] impl Handler<Request> for MyHandler { type Output = Result<Response>; async fn call(&self, req: Request) -> Self::Output { let path = req.path().clone(); let method = req.method().clone(); let code = self.code.fetch_add(1, Ordering::SeqCst); Ok(format!("code = {}, method = {}, path = {}", code, method, path).into_response()) } }
路由传参
Viz 允许更灵活地组织代码。
async fn show_user(mut req: Request) -> Result<Response> { let Params(id) = req.extract::<Params<u64>>().await?; Ok(format!("post {}", id).into_response()) } async fn show_user_ext(Params(id): Params<u64>) -> Result<impl IntoResponse> { Ok(format!("Hi, NO.{}", id)) } async fn show_user_wrap(req: Request) -> Result<impl IntoResponse> { // https://github.com/rust-lang/rust/issues/48919 // show_user_ext.call(req).await FnExt::call(&show_user_ext, req).await } let app = Router::new() .get("/users/:id", show_user) .get("/users_wrap/:id", show_user_wrap) .get("/users_ext/:id", show_user_ext.into_handler());
链式组合程序
HandlerExt是Handler的拓展特质，它提供了各种方便的组合函数。比如FutureExt和StreamExt特质。
async fn index(_: Request) -> Result<Response> { Ok(Response::text("hyper")) } async fn before(req: Request) -> Result<Request> { if req.method() == Method::POST { Ok(req) } else { Err(StatusCode::METHOD_NOT_ALLOWED.into_error()) } } async fn around<H>((req, handler): Next<Request, H>) -> Result<Response> where H: Handler<Request, Output = Result<Response>> + Clone, { // before ... let result = handler.call(req).await; // after ... result } async fn after(result: Result<Response>) -> Result<Response> { result.map(|mut res| { *res.status_mut() = StatusCode::NO_CONTENT; res }) } let routing = Router::new() .get("/", index.before(before).around(around).after(after));
中间件
Viz 的中间件和处理程序具有共同的Handler特质，因此它很容易实现和扩展中间件。
我们可以将中间件添加到单个处理程序或所有处理程序。
我们还可以在构造过程中使用Transform特质 trait 来包装内部处理程序。
async fn index(_: Request) -> Result<Response> { Ok(StatusCode::OK.into_response()) } async fn not_found(_: Request) -> Result<impl IntoResponse> { Ok(StatusCode::OK) } async fn show_user(Params(id): Params<u64>) -> Result<impl IntoResponse> { Ok(format!("post {}", id)) } // middleware fn async fn around<H>((req, handler): Next<Request, H>) -> Result<Response> where H: Handler<Request, Output = Result<Response>>, { // before ... let result = handler.call(req).await; // after ... result } // middleware struct #[derive(Clone)] struct MyMiddleware {} #[async_trait] impl<H> Handler<Next<Request, H>> for MyMiddleware where H: Handler<Request>, { type Output = H::Output; async fn call(&self, (i, h): Next<Request, H>) -> Self::Output { h.call(i).await } } // A configuration for Timeout Middleware struct Timeout { delay: Duration, } impl Timeout { pub fn new(secs: u64) -> Self { Self { delay: Duration::from_secs(secs) } } } impl<H: Clone> Transform<H> for Timeout { type Output = TimeoutMiddleware<H>; fn transform(&self, h: H) -> Self::Output { TimeoutMiddleware(h, self.delay) } } // Timeout Middleware #[derive(Clone)] struct TimeoutMiddleware<H>(H, Duration); #[async_trait] impl<H> Handler<Request> for TimeoutMiddleware<H> where H: Handler<Request> + Clone, { type Output = H::Output; async fn call(&self, req: Request) -> Self::Output { self.0.call(req).await } } let app = Router::new() .get("/", index // handler level .around(around) .around(MyMiddleware {}) .with(Timeout::new(1)) ) .route("/users/:id", get( show_user .into_handler() .map_into_response() // handler level .around(around) .with(Timeout::new(0)) ) .post( (|_| async { Ok(Response::text("update")) }) // handler level .around(around) .with(Timeout::new(0)) ) // route level .with_handler(MyMiddleware {}) .with(Timeout::new(2)) ) .get("/*", not_found .map_into_response() // handler level .around(around) .around(MyMiddleware {}) ) // router level .with_handler(around) .with_handler(MyMiddleware {}) .with(Timeout::new(4));
参数接收器
从Request中提取参数。
struct Counter(u16); #[async_trait] impl FromRequest for Counter { type Error = Infallible; async fn extract(req: &mut Request) -> Result<Self, Self::Error> { let c = get_query_param(req.query_string()); Ok(Counter(c)) } } fn get_query_param(query: Option<&str>) -> u16 { let query = query.unwrap_or(""); let q = if let Some(pos) = query.find('q') { query.split_at(pos + 2).1.parse().unwrap_or(1) } else { 1 }; cmp::min(500, cmp::max(1, q)) }
路由
识别URL和分配处理器。
一个简单的路由
async fn index(_: Request) -> Result<Response> { Ok(().into_response()) } let root = Router::new() .get("/", index) .route("/about", get(|_| async { Ok("about") })); let search = Router::new() .route("/", Route::new().get(|_| async { Ok("search") }));
CRUD操作
添加带请求方式的方法。
async fn index_todos(_: Request) -> Result<impl IntoResponse> { Ok(()) } async fn create_todo(_: Request) -> Result<&'static str> { Ok("created") } async fn new_todo(_: Request) -> Result<Response> { Ok(Response::html(r#" <form method="post" action="/"> <input name="todo" /> <button type="submit">Create</button> </form> "#)) } async fn show_todo(mut req: Request) -> Result<Response> { let Params(id): Params<u64> = req.extract().await?; Ok(Response::text(format!("todo's id is {}", id))) } async fn update_todo(_: Request) -> Result<()> { Ok(()) } async fn destroy_todo(_: Request) -> Result<()> { Ok(()) } async fn edit_todo(_: Request) -> Result<()> { Ok(()) } let todos = Router::new() .route("/", get(index_todos).post(create_todo)) .post("/new", new_todo) .route("/:id", get(show_todo).patch(update_todo).delete(destroy_todo)) .get("/:id/edit", edit_todo);
资源
// GET `/search` async fn search_users(_: Request) -> Result<Response> { Ok(Response::json::<Vec<u64>>(vec![])?) } // GET `/` async fn index_users(_: Request) -> Result<Response> { Ok(Response::json::<Vec<u64>>(vec![])?) } // GET `/new` async fn new_user(_: Request) -> Result<&'static str> { Ok("User Form") } // POST `/` async fn create_user(_: Request) -> Result<&'static str> { Ok("Created User") } // GET `/user_id` async fn show_user(_: Request) -> Result<&'static str> { Ok("User ID 007") } // GET `/user_id/edit` async fn edit_user(_: Request) -> Result<&'static str> { Ok("Edit User Form") } // PUT `/user_id` async fn update_user(_: Request) -> Result<&'static str> { Ok("Updated User") } // DELETE `/user_id` async fn delete_user(_: Request) -> Result<&'static str> { Ok("Deleted User") } let users = Resources::default() .named("user") .route("/search", get(search_users)) .index(index_users) .new(new_user) .create(create_user) .show(show_user) .edit(edit_user) .update(update_user) .destroy(delete_user);
总结
本期主要是对Rust的轻量级Web框架Viz进行了入门级的了解，并且给出了Viz官方的示例代码，包括中间件，响应处理，路由等组件的用法，可以看出Viz是个纯web框架，非常的简洁。在后续的文章中，将会陆续为大家介绍rust的数据库操作，json操作等相关技术，rust做web后端的相关技术补齐就开始项目实战。如果你对rust感兴趣，请关注本系列文章。
