引言

文件上传是Web应用开发中常见的需求之一，而实时显示文件上传的进度条可以提升用户体验。本教程将介绍如何使用Java后端和Vue前端实现文件上传进度条功能，借助阿里云的OSS服务进行文件上传。

技术栈

• 后端：Java、Spring Boot 、WebSocket Server
• 前端：Vue、WebSocket Client

前端实现

安装依赖

npm install websocket sockjs-client

UploadFiles文件上传组件

注意：异步请求接口的时候，后端返回数据结构如下，实际根据自己需求调整返回。

{
    "code": 200,
    "message": "成功",
    "data": {
        "requestId": "file_1697165869563",
    }
}

创建UploadFiles组件，前端主业务逻辑：上传文件方法和初始化websocket服务方法。这里requestId也是你上传文件后到OSS的Bucket桶的文件名。后面后端展示逻辑有显示，实际根据自己需求调整。

<template>
  <div>
    <input type="file" @change="handleFileChange" />
    <button @click="uploadFile">上传</button>
    <div>{{ progress }}</div>
  </div>
</template>

<script>
  import axios from 'axios';
  import { Message } from 'element-ui';
  import { w3cwebsocket as WebSocket } from 'websocket';

  export default {
    data() {
      return {
        file: null,
        progress: '0%',
        requestId: '',
        websocket: null,
        isWebSocketInitialized: false,
      };
    },
    methods: {
      handleFileChange(event) {
        this.file = event.target.files[0];
      },
      initConnect(){
        if (!this.isWebSocketInitialized) {
          this.initWebSocket();
          this.isWebSocketInitialized = true;
        }
      },
      generateUniqueID() {
        // 使用时间戳来生成唯一ID
        const timestamp = new Date().getTime();
        // 在ID前面添加一个前缀，以防止与其他ID冲突
        const uniqueID = 'file_' + timestamp;
        return uniqueID;
      },
      uploadFile() {
        this.initConnect();
        console.log("isWebSocketInitialized="+this.isWebSocketInitialized)
        const formData = new FormData();
        formData.append('file', this.file);
        formData.append('requestId', this.generateUniqueID());
        axios
          .post('http://localhost:8886/test/upload', formData, {
            headers: {
              'Content-Type': 'multipart/form-data',
            },
            onUploadProgress: (progressEvent) => {
              this.progress = `${Math.round((progressEvent.loaded * 100) / progressEvent.total)}%`;
            },
          })
          .then((response) => {
            if(response.data.code===200){
              this.requestId = response.data.data.requestId;
              console.log('requestId=' + response.data.data.requestId);
            }else{
              // 弹框报错 response.data.message
              console.log("code="+response.data.code+",message="+response.data.message)
              Message.error(response.data.message);
            }
            this.initWebSocket();
          })
          .catch((error) => {
            console.error('Failed to upload file:', error);
          });
      },
      initWebSocket() {
        this.websocket = new WebSocket('ws://localhost:8886/test/upload-progress');
        this.websocket.onmessage = (event) => {
          const progress = event.data;
          console.log('上传进度=' + progress);
          this.progress = progress;
          // if (progress === '100%') {
          //   this.websocket.close();
          // }
        };
        this.websocket.onclose = () => {
          console.log('WebSocket connection closed');
        };
      },
    },
  };
</script>

使用上传组件

测试演示，所以直接在App.vue中使用UploadFiles组件。

<template>
  <div id="app">
    <UploadFiles />
  </div>
</template>

<script>
import UploadFiles from './components/UploadFiles.vue';

export default {
  name: 'App',
  components: {
    UploadFiles
  }
};
</script>

后端实现

添加依赖

maven中添加socket服务依赖

<!--websocket服务-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

WebSocketConfig配置类

创建WebSocket配置类，配置socket服务注册节点、处理跨域问题和添加监听处理器。

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.lang.Nullable;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    private final UploadProgressHandler uploadProgressHandler;

    public WebSocketConfig(UploadProgressHandler uploadProgressHandler) {
        this.uploadProgressHandler = uploadProgressHandler;
    }
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(uploadProgressHandler, "/test/upload-progress").setAllowedOrigins("*").addInterceptors(new HttpSessionHandshakeInterceptor());
    }

    /**
     * 引入定时任务bean，防止和项目中quartz定时依赖冲突
     */
    @Bean
    @Nullable
    public TaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler threadPoolScheduler = new ThreadPoolTaskScheduler();
        threadPoolScheduler.setThreadNamePrefix("SockJS-");
        threadPoolScheduler.setPoolSize(Runtime.getRuntime().availableProcessors());
        threadPoolScheduler.setRemoveOnCancelPolicy(true);
        return threadPoolScheduler;
    }

}

UploadProgressHandler处理器

创建文件上传进程的处理器，继承TextWebSocketHandler，记录文件上传监听器和记录WebSocketSession会话。

import xxxxxx.PutObjectProgressListener;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
@Component
public class UploadProgressHandler extends TextWebSocketHandler {

    private final Map<String, PutObjectProgressListener> uploadProgressMap = new ConcurrentHashMap<>();
    private static final Map<String, WebSocketSession> sessionMap = new ConcurrentHashMap<>();

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) {
        uploadProgressMap.forEach((requestId, progressListener) -> {
            try {
                session.sendMessage(new TextMessage(progressListener.getProgress()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
    }
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception{
        sessionMap.put(session.getId(), session);
        super.afterConnectionEstablished(session);

    }
    public static Map<String, WebSocketSession> getSessionMap() {
        return sessionMap;
    }
    public void addProgressListener(String requestId, PutObjectProgressListener progressListener) {
        uploadProgressMap.put(requestId, progressListener);
    }
    public void removeProgressListener(String requestId) {
        uploadProgressMap.remove(requestId);
    }
}

PutObjectProgressListener文件上传监听器

创建文件上传监听器，监听文件上传的进度，并且同步到socket通信会话中

import com.aliyun.oss.event.ProgressEvent;
import com.aliyun.oss.event.ProgressListener;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;

import java.io.IOException;

/**
 * 重写上传文件监听器
 * @author yangz
 * @date 2023/10/11
 */
public class PutObjectProgressListener implements ProgressListener {

    private final long fileSize;
    private long bytesWritten = 0;
    private WebSocketSession session;

    public PutObjectProgressListener(WebSocketSession session, long fileSize) {
        this.session = session;
        this.fileSize = fileSize;
    }

    public String getProgress() {
        if (fileSize > 0) {
            int percentage = (int) (bytesWritten * 100.0 / fileSize);
            return percentage + "%";
        }
        return "0%";
    }

    @Override
    public void progressChanged(ProgressEvent progressEvent) {
        bytesWritten += progressEvent.getBytes();
        if (fileSize > 0) {
            int percentage = (int) (bytesWritten * 100.0 / fileSize);
            try {
                if (session.isOpen()) {
                    session.sendMessage(new TextMessage(percentage + "%"));
                    System.out.println("上传进度="+percentage + "%");
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

OSSUtil工具类

创建文件上传工具类

import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.model.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.socket.WebSocketSession;
import java.io.*;
import java.util.*;
@Slf4j
public class OSSUtil {
    public static final String endpoint = "http://xxxxx.aliyuncs.com";
    public static final String accessKeyId = "yourAccessKeyId";
    public static final String accessKeySecret = "yourAccessKeySecret";
    private static final String bucketName = yourBucketName;
   
    /**
     * 文件上传并监听进度
     * @param file，requestId，session
     * @return {@link String }
     * @author yangz
     * @date 2023/10/11
     */
    public static String uploadFile(MultipartFile file, String requestId, WebSocketSession session) throws IOException {
        OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);
        // 获取文件大小
        long fileSize = file.getSize();
        String originalFilename = file.getOriginalFilename();
        PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, requestId+originalFilename.substring(originalFilename.lastIndexOf(".")), file.getInputStream());
        // 文件上传请求附加监听器
        putObjectRequest.setProgressListener(new PutObjectProgressListener(session,fileSize));
        ossClient.putObject(putObjectRequest);
        ossClient.shutdown();
        return requestId;
    }
}   

Controller控制器

创建一个测试Controller，API测试文件上传和监听进度

import xxxxxx.UploadProgressHandler;
import xxxxxx.BusinessException;
import xxxxxx.OSSUtil;
import xxxxxx.PutObjectProgressListener;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.socket.*;
import java.io.IOException;
import java.util.*;

@RestController
@Slf4j
@RequestMapping("/test")
public class TestController {
 @Autowired
    private UploadProgressHandler uploadProgressHandler;

    /**
     * 文件上传并监听进度
     * @param file
     * @param requestId
     * @return {@link Map }<{@link String }, {@link String }>
     * @author yangz
     * @date 2023/10/12
     */
    @PostMapping("/upload")
    public Map<String, String> uploadFile(@RequestParam("file") MultipartFile file, String requestId) throws IOException {
        //获取处理器监听到的WebSocketSession集合
        Map<String, WebSocketSession> sessionMap = UploadProgressHandler.getSessionMap();
        Collection<WebSocketSession> sessions = sessionMap.values();
        List<WebSocketSession> values = new ArrayList<>(sessions);
        int size = values.size();
        if (size<1){
            throw new BusinessException(500,"Websocket服务未连接！");
        }
        // 关闭除最后一个之外的其他WebSocketSession
        for (int i = 0; i < size - 1; i++) {
            WebSocketSession session = values.get(i);
            session.close();
            sessionMap.remove(session.getId());
        }
        WebSocketSession webSocketSession = values.get(size-1);
        //添加websocket服务监听文件上传进程
        PutObjectProgressListener progressListener = new PutObjectProgressListener(webSocketSession, file.getSize());
        uploadProgressHandler.addProgressListener(requestId, progressListener);
        // 将 WebSocketSession 传递给 OSSUtil.uploadFile方法
        OSSUtil.uploadFile(file, requestId, webSocketSession);
        //上传完成，移除websocket服务监听
        uploadProgressHandler.removeProgressListener(requestId);

        Map<String, String> resultMap = new HashMap<>();
        resultMap.put("requestId", requestId);
        return resultMap;
    }
}

结果展示

步骤：1、选择文件。2、点击上传按钮。3、可以看到进度标签实时展示百分比进度

结语

通过以上步骤，我们实现了一个包含上传文件和实时显示上传进度的文件上传功能。前端使用Vue编写了上传组件，后端使用Java和Spring Boot进行文件上传处理。通过调用阿里云OSS服务和监听上传文件字节来计算进度，我们能够实时显示文件上传的进度条，提升用户体验。

结束语：人生最大的浪费不是金钱的浪费，而是时间的浪费、认知的迟到