code: public final MultiContext getMultiContext() {
          return new MultiContext(context.getCharset(), this.getContentType(), this.params,
              new BufferedInputStream(Channels.newInputStream(this.channel), Math.max(array.size(), 8192)) {
              {
                  array.copyTo(this.buf);
                  this.count = array.size();
              }
          }, null);
      }
docs: 获取文件上传对象
  
  @return 文件上传对象