Replace the values of the UUID and IssueDate elements with new ones
用新的值替换UUID和IssueDate元素的值
Because the form contains three fields for date , I also create a date instance using a SimpleDateFormat and set that value to issueDate .
由于该表单包含三个日期字段,我也使用SimpleDateFormat创建一个日期实例,并将该值设置为issueDate。