如何使用Express Node.js上传图像文件并显示

Z时代
2024-01-10
分类：问答

我已经使用以下代码：

fileupload.html

<html>
<head>
<title>File Uploading Form</title>
</head>
<body>
<h3>File Upload:</h3>
Select a file to upload: <br />
<form action="http://127.0.0.1:8081/file_upload" method="POST" enctype="multipart/form-data">
<input type="file" name="file" size="50" />
<br />
<input type="submit" value="Upload File" />
</form>
</body>
</html>

fileupload.js：

var express = require('express');
var app = express();
var fs = require("fs");
var bodyParser = require('body-parser');
var multer  = require('multer');
//console.log(multer);
app.use(express.static('public'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(multer({ dest: '/tmp/'}));
app.get('/fileupload.html', function (req, res) {
   res.sendFile( __dirname + "/" + "fileupload.html" );
})
app.post('/file_upload', function (req, res) {
   console.log(req.files.file.name);
   console.log(req.files.file.path);
   console.log(req.files.file.type);
   var file = __dirname + "/" + req.files.file.name;
   fs.readFile( req.files.file.path, function (err, data) {
        fs.writeFile(file, data, function (err) {
         if( err ){
              console.log( err );
         }else{
               response = {
                   message:'File uploaded successfully',
                   filename:req.files.file.name
              };
          }
          console.log( response );
          res.end( JSON.stringify( response ) );
       });
   });
})
var server = app.listen(8081, function () {
  var host = server.address().address
  var port = server.address().port
  console.log("Example app listening at http://%s:%s", host, port)
})

我已经使用以上这些代码进行文件上传，但是在终端中使用节点fileupload.js执行时，出现类型错误 TypeError('app.use()

requires middleware functions');

任何人都可以帮助解决此问题。

回答：

您正在尝试使用multer的旧API。它改变了一段时间，请参阅文档以获取更多信息。

在您上载单个文件的特定情况下，您将删除该app.use(multer({ ... }))行，而使用.single()和req.file一样：

var upload = multer({ dest: '/tmp/'});
// File input field name is simply 'file'
app.post('/file_upload', upload.single('file'), function(req, res) {
  var file = __dirname + '/' + req.file.filename;
  fs.rename(req.file.path, file, function(err) {
    if (err) {
      console.log(err);
      res.send(500);
    } else {
      res.json({
        message: 'File uploaded successfully',
        filename: req.file.filename
      });
    }
  });
});