vue el-upload上传按fileList文件顺序，一次请求上传多个文件，可携带参数_el-upload file-list

解决的问题：

前端往后端法一次请求上传多个文件时，例如后端用MultipartFile[]一次接受多个文件数组。

element-ui的el-upload默认是一个一个上传文件，这时候就需要调用我们自定义文件上传方法利用axios直接进行上传。

 原生手动提交请求(请求多次)

更改后(一次请求)

上传逻辑：

1、:auto-upload="false"  : 设置为 false，表示不自动上传文件，需要手动触发上传。确保在适当的时机手动调用上传方法。

2、:http-request="submitUpload"  这里绑定了上传的请求方法，确保你实现了 submitUpload 方法来处理文件上传的请求。

<el-upload action="#"
    ref="upload"
    on-remove="handleRemove" 
    multiple
    :on-change="handleChange"
    :on-success="handleAvatarSuccess"
    :file-list="fileList"
    :http-request="submitUpload"
    :auto-upload="false"
}

方法代码：

1、在提交表单时，通过手动调用上传方法 this.$refs.upload.submit() 实现手动触发上传

2、利用FormDate携带文件和参数

3、this.$refs.upload.uploadFiles=this.fileList 确保在submitUpload方法中append文件的顺序和fileList一致

data(){
    return{
        fileDate:null,
    }
}
methods:{
    // 表单提交方法
    submitForm(){   
        // 交换位置
        if(this.fileList[1]){
            [this.fileList[0],this.fileList[1]]=[this.fileList[1],this.fileList[0]]
        }         
 
        this.fileDate=new FormData() // 创建 FormData 对象
 
        // 将文件列表设置为上传组件的 uploadFiles 属性
        this.$refs.upload.uploadFiles=this.fileList
        
        // 手动触发上传 调用submitUpload
        this.$refs.upload.submit();
        
        // 将表单参数添加到 FormData 中
        this.fileDate.append('parameter',this.uploadForm.parameter)
 
        // 使用 axios 发送POST请求 上传文件
        axios({                                    
            method: "POST",
            url: '#',
            data:this.fileDate,
            headers: {
                '参数': 'XXX',
            }
        }).then(resp=>{
            if(resp.data.code===200){
                /*调用axios上传文件后不会触发:on-success的方法 
                  上传成功后文件后面不会显示对号，需手动设置*/
                this.fileList.forEach(file=>{
                    file.status='success'
                })
            }
        })   
    },
    submitUpload(file){
        // 当文件上传时调用的方法，将文件添加到 FormData 中
        this.fileDate.append('file',file.file)
    },
}

完整代码

输入url即用

<template>
  <div class="app-container">
    <el-card class="left">
      <div>
        <el-form :model="uploadForm" ref="uploadForm" label-width="10px"                 
            :rules="uploadFormRules">
          <el-form-item prop="parameter">
            <el-input size="mini" v-model="uploadForm.parameter" placeholder="请输入参数">
            </el-input>
          </el-form-item>
          <el-form-item prop="file" :style="{marginBottom: '12px'}">
            <el-upload action="#"
              class="upload-demo"
              ref="upload"
              :on-remove="handleRemove" 
              multiple
              :on-change="handleChange"
              :on-success="handleAvatarSuccess"
              :file-list="fileList"
              :http-request="submitUpload"
              :auto-upload="false"
              >
              <div class="el-upload-dragger" v-loading="loading"
                  element-loading-text="正在上传文件"
                  element-loading-spinner="el-icon-loading"
                  element-loading-background="rgba(0, 0, 0, 0.8)">
                  <i class="el-icon-upload" :style="{fontSize:'66px',marginTop:'25px'}"></i>
                  <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
              </div>
            </el-upload>
            <div class="uploadButton" :style="{display:'flex'}">
              <el-button v-loading="loading" type="primary"
                @click="submitForm" size="mini" :style="{width:'50%'}" 
                icon="el-icon-upload" v-if="fileList.length>0"
                element-loading-text="正在上传文件"
                element-loading-spinner="el-icon-loading">上传</el-button>
              <el-button type="primary" @click="clearFile" size="mini" :disabled="loading"
                :style="{width:'50%'}" icon="el-icon-refresh-left" v-if="fileList.length>0">清空</el-button>
            </div>
          </el-form-item>
        </el-form>  
      </div>
    </el-card>
  </div>
</template>
 
<script>
import axios from 'axios';
export default {
    
  data(){
    return{
      uploadSuccess:false,
      uploadForm:{
        file:[],
        parameter:null,
      },
      loading:false,
      uploadFormRules:{
        parameter:[
            { required: true, message: '请输入参数',}
        ],
      },
      fileList:[],
      fileDate:null,
    }
  },
  methods:{
    clearFile(){
      this.fileList=[]
      this.uploadSuccess=false
    },
 
    submitUpload(file){
      this.fileDate.append('file',file.file)
    },
 
    submitForm(){
      if(!this.loading){  
        if(this.fileList[1]){
          [this.fileList[0],this.fileList[1]]=[this.fileList[1],this.fileList[0]]
        }
        this.fileDate=new FormData()
        this.$refs.upload.uploadFiles=this.fileList
        this.$refs.upload.submit();
        this.fileDate.append('parameter',this.uploadForm.parameter)
        this.loading=true
        axios({
          method: "POST",
          url: '#',
          data:this.fileDate,
        }).then(resp=>{
          console.log(resp)
            this.loading=false
            if(resp.data.code===200){
              this.fileList.forEach(file=>{
                file.status='success'
              })
            }
        })
      }
    },
    handleChange(file, fileList){
        this.fileList=fileList
        this.uploadSuccess=false
    },
    handleRemove(file, fileList) {
        this.fileList=fileList
    },
    handleAvatarSuccess(resp, file, fileList){
      
    },
  },
}
</script>
 
<style scoped>
.app-container{
  width: 100%;
  height: 100%;
  padding: 0;
  margin: 0;
  display: flex;
}
.left{
    margin-top: 10px;
    width: 330px;
    margin-left: 40%;
}
.el-upload-dragger {
    background-color: #fff;
    border: 1px dashed #d9d9d9;
    border-radius: 6px;
    box-sizing: border-box;
    width: 275px;
    height: 100%;
    text-align: center;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}
.app-container .uploadButton /deep/ .el-loading-mask{
    display: flex;
    align-items: center;
    justify-content:center;
}
.app-container .uploadButton /deep/ .el-loading-spinner{
    display: flex;
    align-items: center;
    justify-content:center;
    top:10%;
    margin-top: 0;
}
.app-container .el-upload-dragger /deep/ .el-loading-spinner{
    top:25%;
    margin-top: 0;
}
</style>