# 1.创建空操作
---
* 在操作列表中，新增空操作，修改默认的空操作代码，调用接口将会使用该操作代码。
# 2.注册服务插件代码
---
*将插件绑定到空操作上
```
public override void AfterExecuteOperationTransaction(AfterExecuteOperationTransaction e)
{
base.AfterExecuteOperationTransaction(e);
try
{
foreach (DynamicObject billObj in e.DataEntitys)
{
string keyId = Convert.ToString(billObj["Id"]);
string billNo = Convert.ToString(billObj["BillNo"]);
//获取附件下载地址
string downurl = Convert.ToString(this.Option.GetVariables()["Parameters"]);
string formId = this.BusinessInfo.GetForm().Id;
//根据下载地址提取文件名
string filename = getFileName(downurl);
string fileUrl = PathUtils.GetPhysicalPath(KeyConst.TEMPFILEPATH, filename);
if (File.Exists(fileUrl))
{
File.Delete(fileUrl);
}
//下载附件
FileUploadResult uploadResult = UploadAttachment(this.Context, fileUrl, filename);
//将附件保存到单据上
SaveAttachmentData(this.Context, uploadResult, formId, keyId, billNo);
}
}
```
# 3.调用接口
---
* 引用组件
K3.ExcuteOperation(formId, "DOWNCRM", postData)
* 无组件
接口地址 http://127.0.0.1/k3cloud/Kingdee.BOS.WebApi.ServicesStub.DynamicFormService.ExcuteOperation.common.kdsvc
```
{"parameters": ["SAL_SaleOrder","DOWNCRM","{\"Numbers\":['XSDD000068'],\"Ids\":\"\"}"]
}
```
具体的代码可按照业务场景进行调整。
这个调用什么类库？
