中间件 (Middleware)

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

// 如果内部使用 `await`，此函数可标记为 `async`
export function middleware(request: NextRequest) {
  return NextResponse.redirect(new URL('/home', request.url))
}

// 查看下方的"路径匹配"了解更多
export const config = {
  matcher: '/about/:path*',
}

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

export function middleware(request: NextRequest) {
  if (request.nextUrl.pathname.startsWith('/about')) {
    return NextResponse.rewrite(new URL('/about-2', request.url))
  }

  if (request.nextUrl.pathname.startsWith('/dashboard')) {
    return NextResponse.rewrite(new URL('/dashboard/user', request.url))
  }
}

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

export function middleware(request: NextRequest) {
  // 假设传入请求中存在 "Cookie:nextjs=fast" 头
  // 使用 `RequestCookies` API 从请求中获取cookie
  let cookie = request.cookies.get('nextjs')
  console.log(cookie) // => { name: 'nextjs', value: 'fast', Path: '/' }
  const allCookies = request.cookies.getAll()
  console.log(allCookies) // => [{ name: 'nextjs', value: 'fast' }]

  request.cookies.has('nextjs') // => true
  request.cookies.delete('nextjs')
  request.cookies.has('nextjs') // => false

  // 使用 `ResponseCookies` API 在响应上设置cookie
  const response = NextResponse.next()
  response.cookies.set('vercel', 'fast')
  response.cookies.set({
    name: 'vercel',
    value: 'fast',
    path: '/',
  })
  cookie = response.cookies.get('vercel')
  console.log(cookie) // => { name: 'vercel', value: 'fast', Path: '/' }
  // 传出响应将包含 `Set-Cookie:vercel=fast;path=/` 头。

  return response
}

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

export function middleware(request: NextRequest) {
  // 克隆请求头并设置新头 `x-hello-from-middleware1`
  const requestHeaders = new Headers(request.headers)
  requestHeaders.set('x-hello-from-middleware1', 'hello')

  // 您也可以在 NextResponse.rewrite 中设置请求头
  const response = NextResponse.next({
    request: {
      // 新请求头
      headers: requestHeaders,
    },
  })

  // 设置新响应头 `x-hello-from-middleware2`
  response.headers.set('x-hello-from-middleware2', 'hello')
  return response
}

import { NextRequest, NextResponse } from 'next/server'

const allowedOrigins = ['https://acme.com', 'https://my-app.org']

const corsOptions = {
  'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
  'Access-Control-Allow-Headers': 'Content-Type, Authorization',
}

export function middleware(request: NextRequest) {
  // 检查请求中的来源
  const origin = request.headers.get('origin') ?? ''
  const isAllowedOrigin = allowedOrigins.includes(origin)

  // 处理预检请求
  const isPreflight = request.method === 'OPTIONS'

  if (isPreflight) {
    const preflightHeaders = {
      ...(isAllowedOrigin && { 'Access-Control-Allow-Origin': origin }),
      ...corsOptions,
    }
    return NextResponse.json({}, { headers: preflightHeaders })
  }

  // 处理简单请求
  const response = NextResponse.next()

  if (isAllowedOrigin) {
    response.headers.set('Access-Control-Allow-Origin', origin)
  }

  Object.entries(corsOptions).forEach(([key, value]) => {
    response.headers.set(key, value)
  })

  return response
}

export const config = {
  matcher: '/api/:path*',
}

import { NextRequest } from 'next/server'
import { isAuthenticated } from '@lib/auth'

// 将中间件限制为以 `/api/` 开头的路径
export const config = {
  matcher: '/api/:function*',
}

export function middleware(request: NextRequest) {
  // 调用身份验证函数检查请求
  if (!isAuthenticated(request)) {
    // 返回 JSON 格式的错误消息
    return Response.json(
      { success: false, message: 'authentication failed' },
      { status: 401 }
    )
  }
}