Javascript 如何使用Socket IO上传图像文件？

我正在学校制作一个聊天应用程序作为一个项目，我正在尝试添加一个onClick来运行一个函数，它使用socket io文件上传来运行一个提示函数。 从套接字io文件上载文档。 调用此方法时，将提示用户选择要上载的文件

JavaScript:

document.getElementById("file_button").addEventListener("click", instance.prompt, false);
HTML:

<button id="file_button">Upload File</button>

后端-

www.js-

/**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('cryptidbackend:server');
var http = require('http').createServer(app);
const io = require('socket.io')(http);
const siofu = require('socketio-file-upload')
const cors = require('cors');
app.use(cors());
// Socket.io 

io.on('connection', function (socket) {
  const uploader = new siofu(socket);
  uploader.prompt(document.getElementById("InputAddon"))
  uploader.listen(socket)
  socket.on('sent message', function (msg) {
    console.log('message' + ' : ' + JSON.stringify(msg))
    socket.broadcast.emit('message', msg);
  })
})


/**
 * Get port from environment and store in Express.
 */
http.listen(3001, function () {
  console.log('listening on 3001')
})

app.js-

const siofu = require('socketio-file-upload')
const app = express()

const cors = require("cors");
const bodyParser = require("body-parser");
const logger = require("morgan");
const session = require("express-session");
const FileStore = require("session-file-store")(session);
const upload = require("express-fileupload");

app.use(siofu.router)

app.use(upload());
console.log("Server Started!");

app.use(logger("dev"));

app.use(cors());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(
  session({
    resave: false,
    secret: "hello",
    saveUninitialized: true,
    is_logged_in: false,
  })
);

const indexRouter = require("./routes/index");
app.use("/", indexRouter);

const usersRouter = require('./routes/users');
app.use('/users', usersRouter);

module.exports = app;

---

如果你有任何问题，或可以给我任何提示，请做我只有大约5个月进入我的编码职业，所以我仍然有很多东西要学习

首先，这部分代码在后端，后端没有文档或窗口。这意味着document.getElementById在这里不起作用

 io.on('connection', function (socket) {
  const uploader = new siofu(socket);
  uploader.prompt(document.getElementById("InputAddon"))
  uploader.listen(socket)
  socket.on('sent message', function (msg) {
    console.log('message' + ' : ' + JSON.stringify(msg))
    socket.broadcast.emit('message', msg);
  })
})

然后没有上传文件位置/dir被定义

你可以看到这个例子

快速文件上传

app.use(fileUpload({
    useTempFiles : true,
    tempFileDir : '/tmp/'
}));

socketio文件上传

io.on("connection", function(socket){
    var uploader = new siofu();
    uploader.dir = "/path/to/save/uploads";  ***//upload directory***
    uploader.listen(socket);
});

所以我建议你通过下面提到的链接更新你的代码

---

为了从前端上传文件，您需要做的是在useEffect inside ChatBox组件中在前端创建socket file upload的实例

此外，您还需要创建一个虚拟的隐藏输入，当单击上载按钮时，您可以在该输入上模拟单击，还需要创建一个可以监听的输入

需要添加的小代码段

  const fileRef = useRef(null);
  useEffect(() => {
     const siofu = new SocketIOFileUpload(state.socket);
     // call listen on input and pass the hidden input ref
     siofu.listenOnInput(fileRef.current);
  }, [state.socket])

  const InputAddon = () => {
     // Trigger click on fileRef input
     fileRef.current.click();
  }

带输入的完整组件代码

import SocketIOFileUpload from 'socketio-file-upload';
const ChatBox = () => {
  const [textValue, changeTextValue] = React.useState('');

  const { state, dispatch } = React.useContext(CTX);
  console.log(state.user)
  React.useEffect(() => {
    console.log(state.user)

    state.socket.on('message', function (msg) {
      console.log("chat message recieved")
      dispatch('RECEIVE_MESSAGE', msg);
    })
  }, [])





  const onKeyPressHandler = (e) => {
    if (e.key === 'Enter') {
      e.preventDefault();
      console.log("PRESSED")
      state.socket.emit('sent message', { from: state.user, msg: textValue, channel: state.selectedChannel });
      dispatch('RECEIVE_MESSAGE', { from: state.user, msg: textValue, channel: state.selectedChannel });
      changeTextValue('')
    }
  }

  const onChangeHandler = e => {
    changeTextValue(e.target.value);
  }
  const fileRef = useRef(null);
  useEffect(() => {
     const siofu = new SocketIOFileUpload(state.socket);
     // call listen on input and pass the hidden input ref
     siofu.listenOnInput(fileRef.current);
  }, [state.socket])

  const InputAddon = () => {
     // Trigger click on fileRef input
     fileRef.current.click();
  }

  return (

    <Layout>
      <Sidebar />
      <Wrapper>
        <InnerBoxWrapper>
          <InnerBox>
            <UserMessage />
            <InputWrapper>
              <InputAddons id="InputAddon">
                <FontAwesomeIcon icon={faPlus} onClick={InputAddon}></FontAwesomeIcon>
              </InputAddons>
               <input
                ref={fileRef}
                label="file-picker"
                type="file"
                style={{display: 'none'}}
              />
              <input
                label="Send a chat"
                onChange={onChangeHandler}
                value={textValue}
                onKeyPress={onKeyPressHandler}
              />
            </InputWrapper>
          </InnerBox>
        </InnerBoxWrapper>
      </Wrapper>
    </Layout>
  )
}

---

app.js

const siofu = require('socketio-file-upload')
const app = express()

const cors = require("cors");
const bodyParser = require("body-parser");
const logger = require("morgan");
const session = require("express-session");
const FileStore = require("session-file-store")(session);

app.use(siofu.router)

console.log("Server Started!");

app.use(logger("dev"));

app.use(cors());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(
  session({
    resave: false,
    secret: "hello",
    saveUninitialized: true,
    is_logged_in: false,
  })
);

const indexRouter = require("./routes/index");
app.use("/", indexRouter);

const usersRouter = require('./routes/users');
app.use('/users', usersRouter);

---

从目标位置识别图像文件，然后使用

public static byte[] readBytesFromFile(File file) throws IOException 
{
       InputStream is = new FileInputStream(file);

       // Get the size of the file
       long length = file.length();

       // You cannot create an array using a long type.
       // It needs to be an int type.
       // Before converting to an int type, check
       // to ensure that file is not larger than Integer.MAX_VALUE.
       if (length > Integer.MAX_VALUE) 
       {
           is.close();
         throw new IOException("Could not completely read file " + file.getName() + " as it is too long (" + length + " bytes, max supported " + Integer.MAX_VALUE + ")");

       }

       // Create the byte array to hold the data
       byte[] bytes = new byte[(int)length];

       // Read in the bytes
       int offset = 0;
       int numRead = 0;
       while (offset < bytes.length && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) 
       {
           offset += numRead;
       }

       // Ensure all the bytes have been read in
       if (offset < bytes.length) 
       {
           is.close();
           throw new IOException("Could not completely read file "   +file.getName());
       }

       // Close the input stream and return bytes
       is.close();
       return bytes;
}

public static byte[]readBytesFromFile（文件文件）引发IOException
{
InputStream is=新文件InputStream（文件）；
//获取文件的大小
long length=file.length（）；
//不能使用长类型创建数组。
//它必须是int类型。
//在转换为int类型之前，请检查
//以确保文件不大于Integer.MAX_值。
if（长度>整数最大值）
{
is.close（）；
抛出新IOException（“无法完全读取文件”+file.getName（）+，因为它太长（“+length+”字节，支持的最大值“+Integer.max_VALUE+”））；
}
//创建字节数组以保存数据
字节[]字节=新字节[（int）长度]；
//读入字节
整数偏移=0；
int numRead=0；
而（偏移量=0）
{
偏移量+=numRead；
}
//确保已读入所有字节
if（偏移量<字节长度）
{
is.close（）；
抛出新IOException（“无法完全读取文件”+file.getName（））；
}
//关闭输入流并返回字节
is.close（）；
返回字节；
}

将图像数据存储到字节数组中

然后，提及你的目的地并申请

它将运行

import SocketIOFileUpload from 'socketio-file-upload';
const ChatBox = () => {
  const [textValue, changeTextValue] = React.useState('');

  const { state, dispatch } = React.useContext(CTX);
  console.log(state.user)
  React.useEffect(() => {
    console.log(state.user)

    state.socket.on('message', function (msg) {
      console.log("chat message recieved")
      dispatch('RECEIVE_MESSAGE', msg);
    })
  }, [])





  const onKeyPressHandler = (e) => {
    if (e.key === 'Enter') {
      e.preventDefault();
      console.log("PRESSED")
      state.socket.emit('sent message', { from: state.user, msg: textValue, channel: state.selectedChannel });
      dispatch('RECEIVE_MESSAGE', { from: state.user, msg: textValue, channel: state.selectedChannel });
      changeTextValue('')
    }
  }

  const onChangeHandler = e => {
    changeTextValue(e.target.value);
  }
  const fileRef = useRef(null);
  useEffect(() => {
     const siofu = new SocketIOFileUpload(state.socket);
     // call listen on input and pass the hidden input ref
     siofu.listenOnInput(fileRef.current);
  }, [state.socket])

  const InputAddon = () => {
     // Trigger click on fileRef input
     fileRef.current.click();
  }

  return (

    <Layout>
      <Sidebar />
      <Wrapper>
        <InnerBoxWrapper>
          <InnerBox>
            <UserMessage />
            <InputWrapper>
              <InputAddons id="InputAddon">
                <FontAwesomeIcon icon={faPlus} onClick={InputAddon}></FontAwesomeIcon>
              </InputAddons>
               <input
                ref={fileRef}
                label="file-picker"
                type="file"
                style={{display: 'none'}}
              />
              <input
                label="Send a chat"
                onChange={onChangeHandler}
                value={textValue}
                onKeyPress={onKeyPressHandler}
              />
            </InputWrapper>
          </InnerBox>
        </InnerBoxWrapper>
      </Wrapper>
    </Layout>
  )
}

var app = require('../app');
var debug = require('debug')('cryptidbackend:server');
const socketio = require('socket.io');

/**
 * Get port from environment and store in Express.
 */
app.listen(3001, function () {
  console.log('listening on 3001')
})



var io = socketio.listen(app);

// Socket.io 

io.sockets.on('connection', function (socket) {
    const uploader = new siofu(socket);
    uploader.listen(socket)
    uploader.dir = "/srv/uploads";
    uploader.listen(socket);

    // Do something when a file is saved:
    uploader.on("saved", function(event){
        console.log(event.file);
    });

    // Error handler:
    uploader.on("error", function(event){
        console.log("Error from uploader", event);
    });
})

const siofu = require('socketio-file-upload')
const app = express()

const cors = require("cors");
const bodyParser = require("body-parser");
const logger = require("morgan");
const session = require("express-session");
const FileStore = require("session-file-store")(session);

app.use(siofu.router)

console.log("Server Started!");

app.use(logger("dev"));

app.use(cors());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(
  session({
    resave: false,
    secret: "hello",
    saveUninitialized: true,
    is_logged_in: false,
  })
);

const indexRouter = require("./routes/index");
app.use("/", indexRouter);

const usersRouter = require('./routes/users');
app.use('/users', usersRouter);

public static byte[] readBytesFromFile(File file) throws IOException 
{
       InputStream is = new FileInputStream(file);

       // Get the size of the file
       long length = file.length();

       // You cannot create an array using a long type.
       // It needs to be an int type.
       // Before converting to an int type, check
       // to ensure that file is not larger than Integer.MAX_VALUE.
       if (length > Integer.MAX_VALUE) 
       {
           is.close();
         throw new IOException("Could not completely read file " + file.getName() + " as it is too long (" + length + " bytes, max supported " + Integer.MAX_VALUE + ")");

       }

       // Create the byte array to hold the data
       byte[] bytes = new byte[(int)length];

       // Read in the bytes
       int offset = 0;
       int numRead = 0;
       while (offset < bytes.length && (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) 
       {
           offset += numRead;
       }

       // Ensure all the bytes have been read in
       if (offset < bytes.length) 
       {
           is.close();
           throw new IOException("Could not completely read file "   +file.getName());
       }

       // Close the input stream and return bytes
       is.close();
       return bytes;
}