测试了拦截路由，设置跨域两者效果一样：
index.js:

router.use(function(req, res, next) {
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
    res.header('Access-Control-Allow-Headers', 'Content-Type');
   const url=req.url
    if (url.indexOf('test')!=-1){
       return res.json('test')
    }
    next();
});
...

router.all('*',function(req, res, next) {
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
    res.header('Access-Control-Allow-Headers', 'Content-Type');
    const url=req.url
    if (url.indexOf('test')!=-1){
       return res.json('test')
    }
    next();
});
...

本地测试的，两者有什么区别，应该使用哪种？