Koa 代理http请求，解决跨域问题

1、为什么用Koa做跨域代理？

"最初为了解决跨域问题，我把站点部署到了nginx上就解决了问题。一次偶然的面试机会，面试官提出了一个假设我需要对提交api和api返回的数据进行适配，那么nginx是不是就无法满足了。当然这个问题的提出，让我考虑到其实如果自己搭一个站点，通过这个站点进行转发，适配第三方api的请求和应答不就好了。那么要搭一个站点的语言其实有很多，例如.net,java,nodejs,php...，那为什么最后选择nodejs呢？对于我来说最重要的原因，应该就是nodejs的轻量级和javascript语言亲和性。

2、搭建nodejs应用

由于Koa2刚出，毕竟学技术，那么就学最新的。

既然搭建程序那么就从程序的入口开始做，首先写程序的路由

const fs = require('fs')const Router = require('koa-router');const {httpHandle} = require('../Infrastructure/httpHandle');const koaBody = require('koa-body')({ multipart :true});const render = (page) => { return new Promise((resolve, reject) => { let viewUrl = `./view/${page}` fs.readFile(viewUrl, "binary", (err, data) => { if (err) { reject(err) } else { resolve(data) } }) })}let api = new Router();api.get('*', httpHandle) .post('*', koaBody, httpHandle) .put('*', koaBody, httpHandle).del('*', koaBody, httpHandle);let common = new Router();common.get('*', async (ctx) => { ctx.body = await render('index.html');})let router = new Router();router.use('/api', api.routes(), api.allowedMethods());router.use('/', common.routes(), common.allowedMethods());module.exports = router;

其次就是处理代理的请求

const httpRequest = (ctx) => { return new Promise((resolve) => { delete ctx.request.header.host; const options = { host, port, path: ctx.request.url.substr(4, ctx.request.url.length), method: ctx.request.method, headers: ctx.request.header } let requestBody='', body, head, chunks = [], fileFields, files, boundaryKey, boundary, endData, filesLength, totallength = 0; if (ctx.request.body) { console.log(ctx.request.header['content-type']) if (ctx.request.header['content-type'].indexOf('application/x-www-form-urlencoded') > -1) { requestBody = query.stringify(ctx.request.body); options.headers['Content-Length'] = Buffer.byteLength(requestBody) } else if (ctx.request.header['content-type'].indexOf('application/json') > -1) { requestBody = JSON.stringify(ctx.request.body); options.headers['Content-Length'] = Buffer.byteLength(requestBody) } else if (ctx.request.header['content-type'].indexOf('multipart/form-data') > -1) { fileFields = ctx.request.body.fields; files = ctx.request.body.files; boundaryKey = Math.random().toString(16); boundary = `\r\n----${boundaryKey}\r\n`; endData = `\r\n----${boundaryKey}--`; filesLength = 0; Object.keys(fileFields).forEach((key) => { requestBody += `${boundary}Content-Disposition:form-data;name="${key}"\r\n\r\n${fileFields[key]}`; }) Object.keys(files).forEach((key) => { requestBody += `${boundary}Content-Type: application/octet-stream\r\nContent-Disposition: form-data; name="${key}";filename="${files[key].name}"\r\nContent-Transfer-Encoding: binary\r\n\r\n`; filesLength += Buffer.byteLength(requestBody,'utf-8') + files[key].size; }) options.headers['Content-Type'] = `multipart/form-data; boundary=--${boundaryKey}`; options.headers[`Content-Length`] = filesLength + Buffer.byteLength(endData); } else { requestBody = JSON.stringify(ctx.request.body) options.headers['Content-Length'] = Buffer.byteLength(requestBody) } } const req = http.request(options, (res) => { res.on('data', (chunk) => { chunks.push(chunk); totallength += chunk.length; }) res.on('end', () => { body = Buffer.concat(chunks, totallength); head = res.headers; resolve({head, body}); }) }) ctx.request.body && req.write(requestBody); if (fileFields) { let filesArr = Object.keys(files); let uploadConnt = 0; filesArr.forEach((key) => { let fileStream = fs.createReadStream(files[key].path); fileStream.on('end', () => { fs.unlink(files[key].path); uploadConnt++; if (uploadConnt == filesArr.length) { req.end(endData) } }) fileStream.pipe(req, {end: false}) }) } else { req.end(); } })}

由此简单的几行代码就实现了通过nodejs实现跨域的请求代理。 github链接

nginx代理config配置 如下

server { listen 1024; server_name tigrex:1024; root home/TuoTuo.v2.UI; index index.html; access_log logs/tigrex.access.log; error_log logs/tigrex.error.log; charset utf-8; location /api { proxy_pass http://127.0.0.1:1023/; proxy_set_header Host $host; proxy_redirect off; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } location / { try_files $uri $uri/ /index.html; } }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。