java - 使用 java websocket API 和 Javascript 上传文件-6ren

java - 使用 java websocket API 和 Javascript 上传文件

转载作者：塔克拉玛干更新时间：2023-11-03 03:00:00

我正在研究websocket，用websocket/json做过聊天程序。但我坚持文件上传 ATM。任何建议和答案将不胜感激。

服务器端:

package websocket;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

import javax.websocket.CloseReason;
import javax.websocket.EndpointConfig;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;

@ServerEndpoint("/receive/fileserver")
public class FileServer {
    @OnOpen
    public void open(Session session, EndpointConfig conf) {
        System.out.println("chat ws server open");
    }

    @OnMessage
    public void processUpload(ByteBuffer msg, boolean last, Session session) {
        System.out.println("Binary message");

        FileOutputStream fos = null;
        File file = new File("D:/download/tmp.txt");
        try {
            fos = new FileOutputStream(file);
        } catch (FileNotFoundException e) {         
            e.printStackTrace();
        }

        byte readdata = (byte) -999;
        while(readdata!=-1) {
            readdata=msg.get();
            try {
                fos.write(readdata);
            } catch (IOException e) {               
                e.printStackTrace();
            }
        }

    }

    @OnMessage
    public void message(Session session, String msg) {
        System.out.println("got msg: " + msg + msg.length());

    }

    @OnClose
    public void close(Session session, CloseReason reason) {
        System.out.println("socket closed: "+ reason.getReasonPhrase());
    }

    @OnError
    public void error(Session session, Throwable t) {
        t.printStackTrace();

    }
}

客户:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Chat</title>
<script type="text/javascript" src="/MyHomePage/jquery-2.0.3.min.js"></script>
</head>
<body>
    <h2>File Upload</h2>
    Select file
    <input type="file" id="filename" />
    <br>
    <input type="button" value="Connect" onclick="connectChatServer()" />
    <br>
    <input type="button" value="Upload" onclick="sendFile()" />
    <script>
        var ws;

        function connectChatServer() {
            ws = new WebSocket(
                    "ws://localhost:8080/MyHomePage/receive/fileserver");

            ws.binaryType = "arraybuffer";
            ws.onopen = function() {
                alert("Connected.")
            };

            ws.onmessage = function(evt) {
                alert(evt.msg);
            };

            ws.onclose = function() {
                alert("Connection is closed...");
            };
            ws.onerror = function(e) {
                alert(e.msg);
            }

        }

        function sendFile() {
            var file = document.getElementById('filename').files[0];
            var reader = new FileReader();
            var rawData = new ArrayBuffer();            

            reader.loadend = function() {

            }
            reader.onload = function(e) {
                rawData = e.target.result;
                ws.send(rawData);
                alert("the File has been transferred.")
            }

            reader.readAsBinaryString(file);

        }


    </script>
</body>
</html>

服务器端关闭原因消息如下

套接字关闭:解码的文本消息对于输出缓冲区来说太大，端点不支持部分消息

Q1:好像是根据关闭原因找的是文本处理方式，而不是二进制处理方式，请问如何解决？

问题 2:我应该将数据类型更改为 Blob 以在 javascript 端传输文件吗？那怎么办呢？

额外的问题:任何人都可以链接 websocket 文件传输的示例源(java websocket 或 javascript 之一/两者)？

感谢阅读:)

最佳答案

经过一些研究和尝试，我发现“reader.readAsBinaryString(file);”是问题 1 的原因。将其更改为“reader.readAsArrayBuffer(file);”我的第一个问题已经解决了。

此外，由于 websocket 会自动将一个文件传输为多个部分数据，因此我将源代码更改如下。 这行得通! 仅当文件大小不是那么大时。 :/

更改服务器端源:

package websocket;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

import javax.websocket.CloseReason;
import javax.websocket.EndpointConfig;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;

@ServerEndpoint("/receive/fileserver")
public class FileServer {
    static File uploadedFile = null;
    static String fileName = null;
    static FileOutputStream fos = null;
    final static String filePath="d:/download/";

    @OnOpen
    public void open(Session session, EndpointConfig conf) {
        System.out.println("chat ws server open");
    }

    @OnMessage
    public void processUpload(ByteBuffer msg, boolean last, Session session) {
        System.out.println("Binary Data");      

        while(msg.hasRemaining()) {         
            try {
                fos.write(msg.get());
            } catch (IOException e) {               
                e.printStackTrace();
            }
        }

    }

    @OnMessage
    public void message(Session session, String msg) {
        System.out.println("got msg: " + msg);
        if(!msg.equals("end")) {
            fileName=msg.substring(msg.indexOf(':')+1);
            uploadedFile = new File(filePath+fileName);
            try {
                fos = new FileOutputStream(uploadedFile);
            } catch (FileNotFoundException e) {     
                e.printStackTrace();
            }
        }else {
            try {
                fos.flush();
                fos.close();                
            } catch (IOException e) {       
                e.printStackTrace();
            }
        }
    }

    @OnClose
    public void close(Session session, CloseReason reason) {
        System.out.println("socket closed: "+ reason.getReasonPhrase());
    }

    @OnError
    public void error(Session session, Throwable t) {
        t.printStackTrace();

    }
}

浏览器(客户端)端:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Chat</title>
<script type="text/javascript" src="/MyHomePage/jquery-2.0.3.min.js"></script>
</head>
<body>
    <h2>File Upload</h2>
    Select file
    <input type="file" id="filename" />
    <br>
    <input type="button" value="Connect" onclick="connectChatServer()" />
    <br>
    <input type="button" value="Upload" onclick="sendFile()" />
    <script>
        var ws;

        function connectChatServer() {
            ws = new WebSocket(
                    "ws://localhost:8080/MyHomePage/receive/fileserver");

            ws.binaryType = "arraybuffer";
            ws.onopen = function() {
                alert("Connected.")
            };

            ws.onmessage = function(evt) {
                alert(evt.msg);
            };

            ws.onclose = function() {
                alert("Connection is closed...");
            };
            ws.onerror = function(e) {
                alert(e.msg);
            }

        }

        function sendFile() {
            var file = document.getElementById('filename').files[0];
            ws.send('filename:'+file.name);
            var reader = new FileReader();
            var rawData = new ArrayBuffer();            
            //alert(file.name);

            reader.loadend = function() {

            }
            reader.onload = function(e) {
                rawData = e.target.result;
                ws.send(rawData);
                alert("the File has been transferred.")
                ws.send('end');
            }

            reader.readAsArrayBuffer(file);

        }


    </script>
</body>
</html>