//设置允许跨域访问该服务.
app.use((req, res, next) => {
res.set({
'Access-Control-Allow-Credentials':true,
'Access-Control-Max-Age':1728000,
'Access-Control-Allow-Origin': req.headers.origin ||'*',
'Access-Control-Allow-Headers':'X-Requested-With,Content-Type',
'Access-Control-Allow-Methods':'PUT,POST,GET,DELETE,OPTIONS',
'Content-Type':'application/json; charset=utf-8'
})
req.method ==='OPTIONS' ? res.status(204).end() : next()
})
