用了connect-history-api-fallback中间件后所有的get请求都会变成index，所以get请求根本没有执行，设置rewrites就行了

const history = require('connect-history-api-fallback')
app.use(history({
  rewrites: [
    {
      from: /^\/index\/.*$/,
      to: function(context) {
          return context.parsedUrl.path
      }
    },
    {
      from: /^\/api\/.*$/,
      to: function(context) {
          return context.parsedUrl.path
      }
    }
  ]
}))