JS异步文件分片断点上传的实现思路

在项目中有时会遇到大文件上传，经常会出现链接超时的问题，所以就需要使用文件分片上传的方式来上传大文件。实现原理就是，在前端将文件分成指定大小的“文件块”，分成多次上传，每次上传前先向后台查询已经上传成功的文件的大小，然后从指定的位置切割一块文件，进行上传，后台接收到文件块后追加到指定的文件中。

这篇博客适合有一些后台基础的朋友，或者有后台配合的前端。

这里需要后台提供两个接口，一个上传文件的接口，一个查询已上传文件大小的接口。

前端代码：https://github.com/li5454yong/FileUpload.git

这里放上后台主要代码

package com.fs.controller;import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.util.Iterator;
import java.util.Map;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.lang3.StringUtils;
import org.csource.ClientGlobal;
import org.csource.common.MyException;
import org.csource.fastdfs.FileInfo;
import org.csource.fastdfs.StorageClient;
import org.csource.fastdfs.TrackerClient;
import org.csource.fastdfs.TrackerServer;
import org.junit.Test;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisShardInfo;
import com.alibaba.fastjson.JSON;
import com.fs.entity.UploadedFileInfo;
import com.fs.util.UploadUtil;
/**
 * @author admin
 *
 * 2016年12月20日下午8:59:38
 */
@Controller
public class FastDFSUpLoadController {
 @Resource
 private UploadUtil uploadUtil;
 @RequestMapping(value = "v1/uploadSize", method = RequestMethod.POST)
 @ResponseBody
 public Long uploadSize(HttpServletRequest request) {
  String name = request.getParameter("name");
  Long size = Long.parseLong(request.getParameter("size"));
  try {
   JedisShardInfo jedisShardInfo = new JedisShardInfo("192.168.0.12");
   Jedis jedis = new Jedis(jedisShardInfo);
   String str = jedis.get(name);
   UploadedFileInfo uploadedFileInfo = null;
   // 如果首次上传，已上传大小为 0
   if (StringUtils.isEmpty(str)) {
    uploadedFileInfo = new UploadedFileInfo();
    jedis.set(name, JSON.toJSONString(uploadedFileInfo));
    jedis.close();
    return 0L;
   }
   uploadedFileInfo = JSON.parseObject(str, UploadedFileInfo.class);
   jedis.close();
   //已经全部上传
   if(size <= uploadedFileInfo.getSize()){
    System.out.println("上传完成");
   }
    //UploadUtil.getFileInfo(uploadedFileInfo.getFileId());
   return uploadedFileInfo.getSize();
  } catch (Exception e) {
   e.printStackTrace();
   return 0L;
  }
 }
 @RequestMapping(value = "v1/uploadFile", method = RequestMethod.POST)
 @ResponseBody
 public int upload(HttpServletRequest request) {
  // CommonsMultipartResolver resolver = new
  // CommonsMultipartResolver(request.getSession().getServletContext());
  MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;
  Iterator t = multiRequest.getFileNames();
  MultipartFile fileDetail = multiRequest.getFile(t.next());
  String name = request.getParameter("name");
  JedisShardInfo jedisShardInfo = new JedisShardInfo("192.168.0.12");
  Jedis jedis = new Jedis(jedisShardInfo);
  UploadedFileInfo uploadedFileInfo = JSON.parseObject(jedis.get(name), UploadedFileInfo.class);
  uploadedFileInfo.setFileName(name);
  String path = "d:/testUpload";
  File file = new File(path);
  if (!file.exists() && !file.isDirectory()) {
   boolean b = file.mkdirs();
  }
  RandomAccessFile randomFile = null;
  try {
   randomFile = new RandomAccessFile(path+"/"+name, "rw");
   randomFile.seek(randomFile.length());
   randomFile.write(fileDetail.getBytes());
   uploadedFileInfo.setLocalPath(path+"/"+name);
   uploadedFileInfo.setSize(randomFile.length());
  } catch (IOException e) {
   e.printStackTrace();
  }finally{
   try {
    randomFile.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  // 将上传文件信息保存到redis
  jedis.set(name, JSON.toJSONString(uploadedFileInfo));
  jedis.close();
  return 0;
 }
}

以上所述是小编给大家介绍的JS异步文件分片断点上传的实现思路，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！