原代码

// src/middleware.js
import { NextResponse } from 'next/server'export function middleware(request) {handleLocale(request)
}// 处理国际化
const handleLocale = (request) => {const locales = ['zh_CN', 'en_US', 'ja_JP']const { pathname } = request.nextUrlconst pathnameHasLocale = locales.some(locale => pathname.startsWith(`/${locale}/`) || pathname === `/${locale}`)// 正确进入到匹配语言的目录，不做处理if (pathnameHasLocale) {// ...}// 没有进入到匹配的语言目录，设置默认语言，重定向到对应的语言目录else {const locale = locales[0]request.nextUrl.pathname = `/${locale}${pathname}`return NextResponse.redirect(request.nextUrl)}
}export const config = {// 中间件运行的路径matcher: [// NEXT.js内部资源路径 /_next// e.g. /_next/static/chunks/webpack.js |  /_next/static/chunks/main-app.js |  /_next/static/chunks/app-pages-internals.js// 不匹配内部资源，内容资源不需要国际化'/((?!_next|favicon.ico).*)',],
}

修改后

NextResponse.redirect 必须要在middleware 方法里执行，不然不生效

// src/middleware.js
export function middleware(request) {const localeStatus = handleLocale(request);if (localeStatus === 'locale redirect') {return NextResponse.redirect(request.nextUrl)}
}// 是否包含国际化的资源路径
const handleLocale = (request) => {const locales = ['zh_CN', 'en_US', 'ja_JP']const { pathname } = request.nextUrlconst pathnameHasLocale = locales.some(locale => pathname.startsWith(`/${locale}/`) || pathname === `/${locale}`)// 正确进入到匹配语言的目录，不做处理if (pathnameHasLocale) {return 'locale matched'}// 没有进入到匹配的语言目录，设置默认语言，重定向到对应的语言目录else {const locale = locales[0]request.nextUrl.pathname = `/${locale}${pathname}`return 'locale redirect'}
}