IOS 多文件上传 Java web端（后台） 使用List 接收出现的问题

NSDictionary *param = @{@"assignee"     :self.userId,
                            @"projectName"  :itemName.text,
                            @"proceedingName":Name.text,
                            @"content"      :content.text,
                            @"urgency"      :string
                            };
    BaseNetwork *net = [BaseNetwork new];
    [net.httpSessionManager.requestSerializer setValue:@"multipart/form-data" forHTTPHeaderField:@"Content-Type"];
    [net uploadImageRequestURL:[NSString stringWithFormat:@"%@act/proceeding/start", GW_Domain] imageArray:self.imageArray parameters:param progress:^(float progress) {

  /**
   * 发起申请(app)
   * 
   * @param proceeding
   * @return
   */
  @ResponseBody
  @RequestMapping("/start")
  // @RequiresPermissions("act:proceeding:apply")
  public R start(Proceeding proceeding) {
    try {
      // 启动事项审批工作流程
      proceedingService.appStartProcess(proceeding, getUser());
      return R.ok();
    } catch (BDException e) {
      LOGGER.error("app端发起事项审批流程异常", e);
      return R.error(e.getMessage());
    } catch (Exception e) {
      LOGGER.error("app端发起事项审批流程异常", e);
      return R.error();
    }
  }

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import org.springframework.web.multipart.MultipartFile;
import com.shengshi.common.domain.UploadFileDO;
import com.shengshi.common.exception.FileException;
import com.shengshi.common.utils.Base64Utils;


public class Proceeding implements Serializable {

  private static final long serialVersionUID = 1L;

  /**
   * 主键UUID
   */
  private String id;

  /**
   * 事项审批申请人
   */
  private Long userId;

  /**
   * 项目名称
   */
  private String projectName;

  /**
   * 事项名称
   */
  private String proceedingName;

  /**
   * 事项内容
   */
  private String content;

  /**
   * 缓急程度 0:常规 1:紧急 2:特级
   */
  private String urgency;

  /**
   * 创建时间
   */
  private Date createTime;

  /**
   * 事项审批状态 0:录入 1:审核中 2:审核通过 3:审核不通过
   */
  private String status;

  /**
   * 事项审批流程实例ID
   */
  private String procInstId;

  /**
   * 任务指定处理人
   */
  private String assignee;
  
  /**
   * 任务发起时间
   */
  private Date applyTime;

  /**
   * 上传文件列表，之所以没有规范为multipartfile是在get方法做了另外封装【要兼容移动端和app】
   */
  private List<Object> files;

  /**
   * 关联文件,多个用逗号分隔
   */
  private String delIds;

  /**
   * 上传文件记录列表
   */
  private List<UploadFileDO> uploadFileList;

  public String getId() {
    return id;
  }

  public void setId(String id) {
    this.id = id;
  }

  public Long getUserId() {
    return userId;
  }

  public void setUserId(Long userId) {
    this.userId = userId;
  }

  public String getProjectName() {
    return projectName;
  }

  public void setProjectName(String projectName) {
    this.projectName = projectName;
  }

  public String getProceedingName() {
    return proceedingName;
  }

  public void setProceedingName(String proceedingName) {
    this.proceedingName = proceedingName;
  }

  public String getContent() {
    return content;
  }

  public void setContent(String content) {
    this.content = content;
  }

  public String getUrgency() {
    return urgency;
  }

  public void setUrgency(String urgency) {
    this.urgency = urgency;
  }

  public Date getCreateTime() {
    return createTime;
  }

  public void setCreateTime(Date createTime) {
    this.createTime = createTime;
  }

  public String getStatus() {
    return status;
  }

  public void setStatus(String status) {
    this.status = status;
  }

  public String getProcInstId() {
    return procInstId;
  }

  public void setProcInstId(String procInstId) {
    this.procInstId = procInstId;
  }

  public String getAssignee() {
    return assignee;
  }

  public void setAssignee(String assignee) {
    this.assignee = assignee;
  }

  public Date getApplyTime() {
    return applyTime;
  }

  public void setApplyTime(Date applyTime) {
    this.applyTime = applyTime;
  }

  public List<Object> getFiles() {
    return files;
  }

  public void setFiles(List<Object> files) {
    this.files = files;
  }

 //之所以封装这个方法，是因为我们需要兼容app（直接form表单提交，文件类型）和h5移动端（将文件用base64 encode一下，以字符串的形式传输）的文件上传
  public List<MultipartFile> getFileList() throws FileException {
    List<MultipartFile> list = new ArrayList<MultipartFile>();
    if (files == null) {
      return list;
    }
    for (Object obj : files) {
      if (obj instanceof MultipartFile) {
        list.add((MultipartFile) obj);
      } else {// 移动app的from提交,文件为base64字符串
        // 截取文件字符串 获取文件的类型和内容 base64文件的形式
        // “data:image/jpeg;base64,kjkjfkj4k5j43kj34j34kj534k5j43j34kj5k34j5534kj5534j4”
        // 这里再说明一下，如果将来对接android图片上传也采取base64方式的时候，
        // 有可能解析文件不全，因为Java后台默认会把“+”（加号）替换成“ ”空格,接收的时候先把空格全部替换成“+”
        String base64Img = obj.toString();
        list.add(Base64Utils.base64ConvertFile(base64Img));
      }
    }
    return list;
  }

  public String getDelIds() {
    return delIds;
  }

  public void setDelIds(String delIds) {
    this.delIds = delIds;
  }

  public List<UploadFileDO> getUploadFileList() {
    return uploadFileList;
  }

  public void setUploadFileList(List<UploadFileDO> uploadFileList) {
    this.uploadFileList = uploadFileList;
  }

}

NSDictionary *param = @{@"assignee"     :self.userId,
                            @"projectName"  :itemName.text,
                            @"proceedingName":Name.text,
                            @"content"      :content.text,
                            @"urgency"      :string，
　　　　　　　　　　　　　　　　　@"files"        :data

                            };
    BaseNetwork *net = [BaseNetwork new];
    [net.httpSessionManager.requestSerializer setValue:@"multipart/form-data" forHTTPHeaderField:@"Content-Type"];
    [net uploadImageRequestURL:[NSString stringWithFormat:@"%@act/proceeding/start", GW_Domain] imageArray:self.imageArray parameters:param progress:^(float progress) {