前端vue elementUI upload上传组件封装&多文件上传&进度条，后端servlet request.getPart()接收文件信息

vue upload组件

选中多个文件上传
通过axios请求 onUploadProgress方法监听
on-progress on-success用这两个钩子函数实现进度条 下面有对应的函数。
本文是每个文件一个请求上传
也可以用一个请求上传多个文件，需要将文件遍历添加到form表单中，后端用 request.getParts(); 获取集合，有需要的可以改造一下。

官网地址：https://element.eleme.cn/#/zh-CN/

<template>

  <div>
    <!-- multiple 允许上传多个文件 -->
    <el-upload
        :disabled="defaultDisabled"
        ref="upload"
        :multiple="multiFile"
        action=""
        :auto-upload="false"
        :file-list = "fileList"
        :http-request="uploadFile"
        :on-change="changeFileLength"
        :on-progress="uploadFileProcess"
        :on-success="handleFileSuccess"
        :on-preview = "handleFilePreview"
        :on-remove = "handleFileRemove"
        :before-upload = "beforeFileUpload"
        :before-remove = "beforeFileRemove"
        :limit="limit"
        :on-exceed = "handleFileExceed">
      <div v-if="!defaultDisabled">
        <el-button slot="trigger" size="small" type="primary">选取文件</el-button>
        <el-button style="margin-left: 10px;" size="small" type="success" @click.stop="upload">上传到服务器</el-button>
      </div>
      <div slot="tip" class="el-upload__tip">文件大小不能超过1GB</div>
    </el-upload>
  </div>

</template>

<script>
module.exports = {
  name: "upload",
  props:{
    data:{
      type:Array,
      default:[],
    },
    businessId:{
      type:String,
      default:"",
    },
    businessType:{
      type:String,
      default:"",
    },
    filePath:{
      type:String,
      required:true, //必须指定路径
      default:"",
    },
    fileSize:{
      type:Number,
      default:(1024 * 1024 * 1024) // 默认1GB
    },
    fileNumber:{
      type:Number,
      default: 5 //默认5个文件
    },
    disabled:{
      type:Boolean,
      default:false,
    },
    multiple:{
      type:Boolean,
      default:true,
    }

  },

  data(){
    return {
      fileList: this.data, // 文件列表
      size:this.fileSize,// 文件大小限制
      limit:this.fileNumber, // 文件数量
      path:this.filePath, // 上传路径
      defaultDisabled: this.disabled, // 是否禁用
      formId: this.businessId, //业务主键
      formTable: this.businessType, //业务表
      multiFile:this.multiple //默认上传多个文件
    }
  },

  created(){
    this.getFileList();
  },
  methods:{

    //文件上传前调用，如果返回false 和 失败状态 就会停止上传 并移除fileList的文件
    beforeFileUpload(file) {
      //校验文件大小
      if (file.size >= this.size) {
        //单位GB
        let gb = (file.size / this.size).toFixed(4);
        this.$notify.error({
          title: '错误',
          message:  `${file.name} 文件大小超出${gb}GB，请重新选择！`
        });
        return false;
      }
    },
    // 将文件名称进行编码 后台进行解码
    changeFileLength(file, fileList){
      let fileName = encodeURI(file.name) // 如果可以上传多个文件，这里需要用fileList.forEach()处理
      let newFile = new File([file.raw],fileName);
      newFile.uid = file.uid; // new File 没有uid属性，会导致组件底层报错，这里手动加上
      file.raw = newFile;  // 替换file的数据
    },

    // 用户点击上传调用
    async upload(){
      // 触发上传 调用配置 :http-request="uploadFile"
      // 即触发 uploadFile函数
      await this.$refs.upload.submit();
      // 上传完成后执行的操作 ...
    },
    // 该函数调用多次
    // 每次param参数传入一个文件
    uploadFile(param){
      // 创建FormData上传
      let form = new FormData();
      form.append('file', param.file)
      form.enctype = "multipart/form-data";
      // 将附加信息添加至FormData
      form.append("filePath", this.path);
      form.append("businessId", this.formId);
      form.append("businessType", this.formTable);
        //上传操作
      this.uploadAttach(form,param).then(res => {
          /*上传成功处理*/
          param.onSuccess(res);
      }).catch(err => {
          /*报错处理*/
          this.$message.error(param.file.name + "上传错误");
          param.onSuccess(err);
          for (let i = 0; i < this.fileList.length; i++) {
            if (param.file.name === this.fileList[i].name) {
              this.fileList.splice(i, 1);
              break;
            }
          }
        });
      // }
    },
    // 上传文件
    uploadAttach(data,fileObject){
      return axios({
        method:'post',
        headers: {"Content-Type": "multipart/form-data"},
        url:"/servlet/uploadServlet",//自定义上传url
        data:data,
        onUploadProgress: progressEvent => {
          fileObject.progressFlag = true;
          fileObject.successFlag = true;
          let percent=(progressEvent.loaded / progressEvent.total * 100) | 0
          fileObject.onProgress({percent});//调用uploader的进度回调
        }
      })
    },
    // 文件上传过程中的函数（在这里获取进度条的进度）
    uploadFileProcess(event, file, fileList) {
      this.fileList = fileList;
      for (let i = 0; i < this.fileList.length; i++) {
        if(file.name === this.fileList[i].name){
          this.fileList[i].progressFlag = true;
          this.fileList[i].successFlag = false;
          if(event.percent != 100){
            this.fileList[i].progressPercent = event.percent;
          }
          break;
        }
      }
    },
    // 文件上传成功的函数（用于文件上传成功之后的逻辑处理）
    handleFileSuccess(res,file,fileList){
      this.fileList = fileList;
      for (let i = 0; i < this.fileList.length; i++) {
        if(file.name === this.fileList[i].name){
          this.fileList[i].progressFlag = true;
          if(file.status == 'success' && res.data.code == 200){
            this.fileList[i].successFlag = true;
            res.data = res.data.data;
          }else{
            this.fileList[i].successFlag = false;
            this.fileList.splice(i, 1);
          }
          break;
        }
      }
    },
    //查看文件
    handleFilePreview(file){
      console.log(file);
    },
    //删除文件
    handleFileRemove(file,fileList){
      console.log(file);
    },
    //文件数超出函数
    handleFileExceed(files,fileList){
      this.$notify.error({
        title: '错误',
        message:  `只能选择${this.limit}个文件，请重新选择文件！`
      });
    },
    //文件删除前的操作
    beforeFileRemove(file, fileList){},
    // 后台获取已经上传的文件列表
    getFileList(){
      if(this.businessId === "") return;
      axios.get("/servlet/uploadServlet",{
        businessId:this.businessId,
      }).then(res => {
        if(res.data.code === 200) this.fileList = res.data.data
      }).catch(err=>{
        this.$message.error("请求失败,请稍后再试!");
      })
    },
  }
}
</script>

<style scoped>

</style>

java servlet请求

• @MultipartConfig 使用这个注解后 用下面方式获取文件
• Part part = request.getPart("file") 获取的是单文件
• Collection<Part> parts = request.getParts(); 获取的多文件

package com.kaiyue.detection.upload;
import com.App.Servlet.AppResponse;
import com.alibaba.fastjson.JSONObject;
import com.kaiyue.common.BeanFactory;
import com.kaiyue.common.resource.AppConfig;
import com.kaiyue.common.util.DateUtil;
import com.kaiyue.jpf.attachment.service.FileService;
import com.kaiyue.jpf.common.resource.CommonResource;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.*;
import java.net.URLDecoder;
import java.util.Collection;
import java.util.HashMap;
import java.util.Random;

@WebServlet(name = "uploadServlet", urlPatterns = "/servlet/uploadServlet")
@MultipartConfig
public class uploadServlet extends HttpServlet {
  @Override
  public void destroy() {
    super.destroy();
  }

  @Override
  protected void doGet(HttpServletRequest request,
                       HttpServletResponse response) throws ServletException, IOException {
    this.doPost(request, response);
  }

  /**
   * @param request
   * @param response
   */
  @Override
  protected void doPost(HttpServletRequest request,
                        HttpServletResponse response) throws IOException, ServletException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    response.setContentType("text/html;charset=utf-8");
    FileService fileService = (FileService) BeanFactory.getBeanByName("fileService");

    AppResponse res = new AppResponse();

    request.setCharacterEncoding("UTf-8");
    String businessId = request.getParameter("businessId");//业务主键
    String filePath = request.getParameter("filePath");//保存路径
    String businessType = request.getParameter("businessType");//业务表名

    HashMap<String, String> returnMap = new HashMap<>();
    String fileId = "";//文件信息的主键
    try {
      //获取文件对象
      Part part = request.getPart("file");
      //获取请求头，请求头的格式：form-data; name="file"; filename="snmp4j--api.zip"
      String header = part.getHeader("content-disposition");
      String fileName = getFileName(header);
      fileName = URLDecoder.decode(fileName, "UTF-8");
//获取配置的磁盘根目录
      String path = AppConfig.getRootPath();
      Random random = new Random();
      int number = random.nextInt(1000);
//防止上传的文件重名 取一个新的名字
      String newFileName = fileName.substring(0, fileName.lastIndexOf(".")) + DateUtil.getTimeStampId() + number +
              fileName.substring(fileName.lastIndexOf("."));
      File dir = new File(path + CommonResource.FILE_SEPARATOR + filePath + CommonResource.FILE_SEPARATOR);
      if (!(dir.exists())) {
        dir.mkdirs();
      }

//写入磁盘
      uploadFile(part, dir + CommonResource.FILE_SEPARATOR + newFileName);
      String projectId = "";
      String userId = "";
//保存到数据库
      fileId = fileService.addFileRecord(fileName, filePath + CommonResource.FILE_SEPARATOR + newFileName, userId,
              businessType, businessId, projectId, part.getSize());

      returnMap.put("fileId", fileId);//主键
      returnMap.put("businessId", businessId);
      res.setData(returnMap);
      res.setCode(AppResponse.OK);
      res.setMessage("上传成功!");
    } catch (Exception e) {
      res.setData(returnMap);
      res.setCode(AppResponse.PARAMETER_ERR);
      res.setMessage("上传失败!");
      e.printStackTrace();
    }

    PrintWriter out = response.getWriter();
    out.println(JSONObject.toJSONString(res));
    out.flush();
    out.close();
  }

  /**
   * 根据请求头解析出文件名
   * 请求头的格式：火狐和google浏览器下：form-data; name="file"; filename="snmp4j--api.zip"
   * IE浏览器下：form-data; name="file"; filename="E:\snmp4j--api.zip"
   *
   * @param header 请求头
   * @return 文件名
   */
  public String getFileName(String header) {
    /**
     * String[] tempArr1 = header.split(";");代码执行完之后，在不同的浏览器下，tempArr1数组里面的内容稍有区别
     * 火狐或者google浏览器下：tempArr1={form-data,name="file",filename="snmp4j--api.zip"}
     * IE浏览器下：tempArr1={form-data,name="file",filename="E:\snmp4j--api.zip"}
     */
    header = header.substring(header.lastIndexOf("\\") + 1).replaceAll("\"", "");

    String[] tempArr1 = header.split(";");
    /**
     *火狐或者google浏览器下：tempArr2={filename,"snmp4j--api.zip"}
     *IE浏览器下：tempArr2={filename,"E:\snmp4j--api.zip"}
     */

    String[] tempArr2 = tempArr1[2].split("=");

    //获取文件名，兼容各种浏览器的写法
    String fileName = tempArr2[1].substring(tempArr2[1].lastIndexOf("\\") + 1).replaceAll("\"", "");
    return fileName;
  }


  private void uploadFile(Part part, String path)
          throws Exception {

    InputStream stream = null;
    OutputStream out = null;
    stream = part.getInputStream();
    out = new FileOutputStream(path);
    int bytesRead = 0;
    byte[] buffer = new byte[8192];
    while ((bytesRead = stream.read(buffer, 0, 8192)) != -1) {
      out.write(buffer, 0, bytesRead);
    }
    out.close();
    stream.close();
  }
}

效果

文件比较大