fix(rust): 🐛 missing about handler.rs notes

docs/rust/base/26-构建多线程web服务器.md

@@ -884,6 +884,97 @@ impl Router {
 }
 ```
 
+### src/handler.rs
+
+```rust
+use crate::request;
+use crate::{request::Request, response::Response};
+use colored::Colorize;
+use std::collections::HashMap;
+use std::time::Duration;
+use std::{env, fs, thread};
+
+// 定义处理器特性(接口)
+pub trait Handler {
+    fn handle(req: &Request) -> Response;
+    fn load_file(file_name: &str) -> Option<String> {
+        // use the CARGO_MANIFEST_DIR constant to get the root path of the current package
+        let default_path = format!("{}/public", env!("CARGO_MANIFEST_DIR"));
+        let public_path = env::var("PUBLIC_PATH").unwrap_or(default_path);
+        let file_path = format!("{}/{}", public_path, file_name);
+
+        println!("{}", format!("file_path:{}", file_path).purple());
+
+        let contents = fs::read_to_string(file_path);
+
+        // convert Result to Option
+        contents.ok()
+    }
+}
+
+pub struct ApiHandler;
+pub struct StaticFileHandler;
+pub struct NotFoundHandler;
+
+// Not Found
+impl Handler for NotFoundHandler {
+    fn handle(_: &Request) -> Response {
+        Response::new("404", None, Self::load_file("404.html"))
+    }
+}
+
+// static file
+impl Handler for StaticFileHandler {
+    fn handle(req: &Request) -> Response {
+        let request::Resource::Path(s) = &req.resource;
+        let route: Vec<&str> = s.split("/").collect();
+        println!("{}:{:?}", "route".cyan(), route);
+        match route[1] {
+            "" | "index.html" => Response::new("200", None, Self::load_file("index.html")),
+            "health" => Response::new("200", None, Self::load_file("health.html")),
+            "sleep.html" => {
+                // for test multiple threads
+                thread::sleep(Duration::from_secs(5));
+                Response::new("200", None, Self::load_file("sleep.html"))
+            }
+            path => {
+                if let Some(contents) = Self::load_file(path) {
+                    let mut headers: HashMap<&str, &str> = HashMap::new();
+                    if path.ends_with(".css") {
+                        headers.insert("Content-Type", "text/css");
+                    } else if path.ends_with(".js") {
+                        headers.insert("Content-Type", "text/javascript");
+                    } else if path.ends_with(".html") {
+                        headers.insert("Content-Type", "text/html");
+                    } else {
+                        headers.insert("Content-Type", "text/plain");
+                    }
+                    return Response::new("200", Some(headers), Some(contents));
+                }
+                return NotFoundHandler::handle(req);
+            }
+        }
+    }
+}
+
+// api service handler
+// TODO: 应该根据请求方法和路径再次分发到
+// 不同的 cntroller, 实现类似 Rest 的 api 风格
+// 比如 get /api/user -> UserApi::index
+// 比如 post /api/user -> UserApi::cerate
+// 这里就不实现了, 直接返回一个固定的 json 字符串
+impl Handler for ApiHandler {
+    fn handle(_req: &Request) -> Response {
+        let mut headers: HashMap<&str, &str> = HashMap::new();
+        headers.insert("Content-Type", "application/json");
+
+        let json_str = String::from("{\"errno\":0,\"msg\":\"success\", \"data\": null}");
+
+        Response::new("200", Some(headers), Some(json_str))
+    }
+}
+```
+
 ### src/response.rs
 
 ```rust