如何使用express nodejs上传图像文件并显示答案

【问题标题】：how to upload image file and display using express nodejs如何使用express nodejs上传图像文件并显示
【发布时间】：2023-03-03 01:29:01
【问题描述】：

我使用了以下代码：

文件上传.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>

文件上传.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)
})

我已经使用上面的这些代码进行文件上传但是当在终端中使用 node fileupload.js 执行时，我收到类型错误TypeError('app.use() requires middleware functions');

谁能帮忙解决这个问题。

【问题讨论】：

标签： javascript node.js file-upload

【解决方案1】：

您正在尝试使用 multer 的旧 API。它不久前发生了变化，请参阅documentation 了解更多信息。

在您上传单个文件的特定情况下，您将删除 app.use(multer({ ... })) 行，而使用 .single() 和 req.file 之类的：

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
      });
    }
  });
});

【讨论】：

非常感谢 mscdex .File 上传成功
@SunilGarg 当您发布到您的服务器时，请确保您在一个名为“文件”的字段中发送您的图像...
我如何将图像路径存储在数据库表（MySQL）中

【解决方案2】：

Multer 向请求对象添加一个主体对象和一个或多个文件对象。 body 对象包含表单文本字段的值，文件或文件对象包含通过表单上传的文件。

使用此代码，希望对您有所帮助。

var express = require('express');
var app = express();
var fs = require("fs");

var bodyParser = require('body-parser');
var multer = require('multer');

app.use(express.static('public'));
app.use(bodyParser.urlencoded({ extended: false }));
var upload = multer({ dest: '/tmp' })

app.get('/fileupload.html', function (req, res) {
   res.sendFile( __dirname + "/" + "fileupload.html" );
})

app.post('/file_upload', upload.single("file"), function (req, res) {
   var file = __dirname + "/" + req.file.originalname;
   fs.readFile( req.file.path, function (err, data) {
        fs.writeFile(file, data, function (err) {
         if( err ){
              console.error( err );
              response = {
                   message: 'Sorry, file couldn\'t be uploaded.',
                   filename: req.file.originalname
              };
         }else{
               response = {
                   message: 'File uploaded successfully',
                   filename: req.file.originalname
              };
          }
          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)
})

【讨论】：

这个解决方案也解决了文件上传问题

【解决方案3】：

上面的解决方案对我不起作用，所以我使用了存储方法：

var express = require('express');
var app = express();
var fs = require("fs");

var bodyParser = require('body-parser');
var multer  = require('multer');

app.use(express.static('public'));
app.use(bodyParser.urlencoded({ extended: false }));

app.get('/index.htm', function (req, res) {
    res.sendFile( __dirname + "/" + "index.htm" );
})


var storage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, './uploads/')
    },
    filename: function (req, file, cb) {
        var ext = require('path').extname(file.originalname);
        ext = ext.length>1 ? ext : "." + require('mime').extension(file.mimetype);
        require('crypto').pseudoRandomBytes(16, function (err, raw) {
            cb(null, (err ? undefined : raw.toString('hex') ) + ext);
        });
    }
});

var upload = multer({ storage: storage });

app.post('/file_upload', upload.any(), function (req, res, next) {
    res.send(req.files);
})

【讨论】：

【解决方案4】：

它对我有效

var express = require('express'),
    http = require('http'),
    formidable = require('formidable'),
    fs = require('fs'),
    path = require('path');
var bodyParser = require('body-parser');
var multer  = require('multer');
var upload = multer({ dest: '/tmp/'});
var app = express();


app.get('/', function(req, res) {
  res.sendFile(path.join(__dirname + '/index.html'));
});

var server = app.listen(3000, function() {
  console.log('leistening on port', server.address().port);
})

app.post('/upload', upload.single('file'), function(req, res) {
  var file = 'uploads' + '/' + req.file.originalname;
  fs.rename(req.file.path, file, function(err) {
    if (err) {
      res.send(500);
    } else {
      res.json({
        message: 'File uploaded successfully',
        filename: req.originalname
      });
    }
  });
});

<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]-->
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <title></title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <link rel="stylesheet" href="">
    </head>
    <body>
            <form action="http://127.0.0.1:3000/upload" enctype="multipart/form-data" method="post">
                <input type="text" name="title">
                <input type="file" name="file">
                <input type="submit" value="Upload">
                
            </form>
    </body>
</html>

【讨论】：

【解决方案5】：

似乎保留原始文件名或扩展名并不安全，我发现/制作了这段代码，通过将 .jpg 添加到您的文件 url 来直接在任何地方显示图像：

restapi.get('/uploads/:id', function (req, res) {
  var storedMimeType = 'image/jpeg';
  res.setHeader('Content-Type', storedMimeType)
 fs.createReadStream(path.join('./uploads/', req.params.id).replace(/\.[^/.]+$/, "")).pipe(res)
})

【讨论】：