H5 ajax递交带有file的form表单

HTML+js：

$(".class").change(function () {
        var id = $(this).attr("id");
        console.debug("id:" + id);
        var formData = new FormData();
        var name = $(this).val();
        formData.append("img",$(this)[0].files[0]);
        formData.append("id",id);
        $.ajax({
            url: "xxx/pic",type: 'POST',data: formData,// 告诉jQuery不要去处理发送的数据
            processData: false,// 告诉jQuery不要去设置Content-Type请求头
            contentType: false,beforeSend: function () {
                console.log("正在进行，请稍候");
            },success: function (responseStr) {
            },error: function (responseStr) {
                console.log("error");
            }
        });
    });

 <tr>
                              
                                <td>
                              <span class="putfile">
                                  <@shiro.hasPermission name="xxx" >
                                      <form action="xxxx/pic" enctype="multipart/form-data">
                                          <input name="${ap_index}" type="file" id="${ap.id}"
                                                 class="class"
                                                 style="height: 22px;width: 30px;">
                                      </form>
                                      <@netCommon.pageBtn url="null" type="info" title="上传图片" icon="photo"  />
                                  </@shiro.hasPermission>
                              </span>
                                </td>
                            </tr>