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);