怎么使用中间件
假设我们做一个需要登录的 app，在浏览器访问任意页面，需要先鉴权，鉴权失败则重定向到登录页面。显然这里用中间件较好。
Egine 结构的 Mount、Handle 和 HandleFunc 方法均支持中间件，函数签名如下：
func (e *Engine) Mount(path string, component any, middlewares ...func(http.Handler) http.Handler) *Engine
func (e *Engine) Handle(path string, handler http.Handler, middlewares ...func(http.Handler) http.Handler) *Engine
func (e *Engine) HandleFunc(path string, handler http.HandlerFunc, middlewares ...func(http.Handler) http.Handler) *Engine一个简单的 demo 代码如下：
package main
import (
"fmt"
"math/rand"
"net/http"
"github.com/zrcoder/amisgo"
"github.com/zrcoder/amisgo/comp"
"github.com/zrcoder/amisgo/model"
"github.com/zrcoder/amisgo/util"
)
const (
loginUrl = "/login"
echoApiUrl = "/api/echo"
)
func main() {
index := comp.Page().InitApi(echoApiUrl).Body("${body}")
login := comp.Page().Body(
comp.Form().Body(
comp.InputEmail().Name("user"),
comp.InputPassword().Name("password"),
),
)
app := amisgo.New().
Mount("/", index, checkAuthMiddleware, testMiddleware).
Mount(loginUrl, login).
HandleFunc(echoApiUrl, echo)
panic(app.Run(":8080"))
}
func checkAuthMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// Pre-processing actions, such as logging access, authentication, etc.
fmt.Println("check auth middleware")
if r.URL.Path != loginUrl && !checkAuth(r) {
util.Redirect(w, r, loginUrl, http.StatusTemporaryRedirect)
return
}
next.ServeHTTP(w, r)
})
}
func testMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("test middleware")
w.Header().Set("test", "test heander value")
next.ServeHTTP(w, r)
// Post-processing actions, such as logging debug information
fmt.Println("response heander for [test]:", w.Header().Get("test"))
})
}
func echo(w http.ResponseWriter, r *http.Request) {
resp := model.SuccessResponse("", model.Data{"body": "Hello, amisgo!"})
w.Write(resp.Json())
}
func checkAuth(r *http.Request) bool {
// Parse the token from the request and process authentication.
// This is just a demonstration; it randomly returns the authentication result.
return rand.Intn(2) == 0
}