问如何利用服务器端呈现功能自宿主盖茨比v4

EN

const express = require('express'); 
const gatsbyExpress = require('gatsby-plugin-express'); 
const app = express();
const port = process.env.PORT || 8080; 
const dev = process.env.NODE_ENV !== "production";

// serve static files before gatsby
Express app.use(express.static('public/')); 
app.use(gatsbyExpress('config/gatsby-express.json', 
  {   
      publicDir: 'public/',
      redirectSlashes: true, 
  }));

app.listen(port, function() {
   console.log(`App started on port ${port}`); 
});