Node.js HTTP服务器中处理文件与图片上传的完整指南

<form enctype="multipart/form-data" action="_URL_" method="POST">
 <input name="userfile1" type="file">
 <input type="submit" value="发送文件">
</form>

Content-Type:application/x-www-form-urlencoded

Content-type: multipart/form-data, boundary=AaB03x

POST / HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip, deflate
Host: itbilu.com
Content-Length: 23
Connection: Keep-Alive
Cache-Control: max-age=0

key1=value1&key2=value2

POST / HTTP/1.1
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryYN9YYwO9ESipYBIx
Accept-Encoding: gzip, deflate
Host: itbilu.com
Content-Length: 22646
Connection: Keep-Alive
Cache-Control: max-age=0

------WebKitFormBoundaryoqBx9oYBhx4SF1YQ
Content-Disposition: form-data; name="myName"

itbilu.com
------WebKitFormBoundaryYN9YYwO9ESipYBIx
Content-Disposition: form-data; name="upload"; filename="41GiLecHO3L.jpg"
Content-Type: image/jpeg

����JFIF��C // 文件的二进制数据
……
--------WebKitFormBoundaryYN9YYwO9ESipYBIx--

const http = require('http');
const fs = require('fs');
const util = require('util');
const querystring =require('querystring');

//用http模块创建一个http服务端
http.createServer(function(req, res) {
 if (req.url == '/upload' && req.method.toLowerCase() === 'get') {
  //显示一个用于文件上传的form
  res.writeHead(200, {'content-type': 'text/html'});
  res.end(
   '<form action="/upload" enctype="multipart/form-data" method="post">'+
    '<input type="file" name="upload" multiple="multiple" />'+
    '<input type="submit" value="Upload" />'+
   '</form>'
  );
 } else if (req.url == '/upload' && req.method.toLowerCase() === 'post') {
  if(req.headers['content-type'].indexOf('multipart/form-data')!==-1)
   parseFile(req, res)
  } else {
   res.end('其它提交方式');
  }
}).listen(3000);

function parseFile (req, res) {
 req.setEncoding('binary');
 var body = '';  // 文件数据
 var fileName = ''; // 文件名
 // 边界字符串
 var boundary = req.headers['content-type'].split('; ')[1].replace('boundary=','');
 req.on('data', function(chunk){
  body += chunk;
 });

 req.on('end', function() {
  var file = querystring.parse(body, '\r\n', ':')

  // 只处理图片文件
  if (file['Content-Type'].indexOf("image") !== -1)
  {
   //获取文件名
   var fileInfo = file['Content-Disposition'].split('; ');
   for (value in fileInfo){
    if (fileInfo[value].indexOf("filename=") != -1){
     fileName = fileInfo[value].substring(10, fileInfo[value].length-1);

     if (fileName.indexOf('\\') != -1){
      fileName = fileName.substring(fileName.lastIndexOf('\\')+1);
     }
     console.log("文件名: " + fileName);
    }
   }

   // 获取图片类型(如：image/gif 或 image/png))
   var entireData = body.toString();
   var contentTypeRegex = /Content-Type: image\/.*/;

   contentType = file['Content-Type'].substring(1);

   //获取文件二进制数据开始位置，即contentType的结尾
   var upperBoundary = entireData.indexOf(contentType) + contentType.length;
   var shorterData = entireData.substring(upperBoundary);

   // 替换开始位置的空格
   var binaryDataAlmost = shorterData.replace(/^\s\s*/, '').replace(/\s\s*$/, '');

   // 去除数据末尾的额外数据，即: "--"+ boundary + "--"
   var binaryData = binaryDataAlmost.substring(0, binaryDataAlmost.indexOf('--'+boundary+'--'));

   // 保存文件
   fs.writeFile(fileName, binaryData, 'binary', function(err) {
    res.end('图片上传完成');
   });
  } else {
   res.end('只能上传图片文件');
  }
 });
}