node作为中间层 —> 跨域请求java后台接口(使用http-proxy-middleware中间件)

情景：利用node的express 作为中间层，跨域调取java后台接口，由于java接口对session有判断，因此每次请求都必须在req的headers中需要带上cookie，否则接口报500错误，通过多次尝试，终于成功调取到接口，代码如下：

 const express = require('express');
 const path = require('path');
 const proxyMiddleware = require('http-proxy-middleware');

 // default port where dev server listens for incoming traffic
 const port = 3335;

 const app = express();

 //设置cookie
 let cookie;
 function relayRequestHeaders(proxyReq, req) {
   if (cookie) {
     proxyReq.setHeader('cookie', cookie);
   }
 };

 function relayResponseHeaders(proxyRes, req, res) {
   let proxyCookie = proxyRes.headers["set-cookie"];
   if (proxyCookie) {
     cookie = proxyCookie;
   }
 };

 let options = {
     target: 'http://192.168.1.2:8081', // target host
     changeOrigin: true, // needed for virtual hosted sites
     pathRewrite: {
         '^/': '/Edit-WS/', // rewrite path
     },
     onProxyReq: relayRequestHeaders,
     onProxyRes: relayResponseHeaders,
 };

 // 静态资源 处理
 app.use(express.static(path.join(__dirname + '/WebRoot')));

 // 访问登录页（/）
 app.get('/', function(req, res, next) {
     console.log('test=============');
     let options = {
         root: __dirname + '/WebRoot/',
         dotfiles: 'deny',
         headers: {
             'x-timestamp': Date.now(),
             'x-sent': true
         }
     };

     let fileName = 'index_2x.html';
     res.sendFile(fileName, options, function(err) {
         if (err) {
             console.log(err);
             res.status(err.status).end();
         } else {
             console.log('Sent:', fileName);
         }
     });
 });

 // 匹配的路由（正则）
 app.use('/**/*.do', proxyMiddleware(options));

 const server = app.listen(port);