public class UploadAction extends ActionSupport { private static final long serialVersionUID = 1L; private static final String CONTENT_TYPE= "text/html; charset=utf-8"; public String execute() { HttpServletResponse response = (HttpServletResponse)ActionContext.getContext().get(org.apache.struts2.StrutsStatics.HTTP_RESPONSE); HttpServletRequest request = (HttpServletRequest)ActionContext.getContext().get(org.apache.struts2.StrutsStatics.HTTP_REQUEST); SingleFileUpload upload = new SingleFileUpload(); try { upload.parseRequest(request); } catch (UnsupportedEncodingException e1) { e1.printStackTrace(); } String temp =ServletActionContext.getServletContext().getRealPath("/") + "upload\temp\"; //��ʱĿ¼ System.out.print("�ϴ�·����"+temp); String loadpath = ServletActionContext.getServletContext().getRealPath("/") + "upload\"; //�ϴ��ļ����Ŀ¼ File file = new File(temp); if(!file.exists()) file.mkdirs(); try { upload.upload(file); response.getWriter().write(upload.getFileItem().getName()); } catch(org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e){ // �ļ���С�������ֵ e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } return null; } } 解释每一行代码

public class UploadAction extends ActionSupport {

//定义一个继承自ActionSupport的类UploadAction，用于文件上传功能

private static final long serialVersionUID = 1L;

//定义一个序列化ID，用于版本控制

private static final String CONTENT_TYPE= "text/html; charset=utf-8";

//定义一个常量CONTENT_TYPE，表示上传文件的内容类型

public String execute() {

//定义一个execute方法，用于执行文件上传操作

HttpServletResponse response = (HttpServletResponse) ActionContext.getContext().get(org.apache.struts2.StrutsStatics.HTTP_RESPONSE);

//获取HttpServletResponse响应对象

HttpServletRequest request = (HttpServletRequest) ActionContext.getContext().get(org.apache.struts2.StrutsStatics.HTTP_REQUEST);

//获取HttpServletRequest请求对象

SingleFileUpload upload = new SingleFileUpload();

//创建SingleFileUpload类的实例

try {
upload.parseRequest(request);
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
}

//解析HttpServletRequest请求对象，获取上传的文件信息

String temp =ServletActionContext.getServletContext().getRealPath("/") + "upload\temp\";

//获取临时目录存储路径

System.out.print("上传路径"+temp);

//输出上传路径

String loadpath = ServletActionContext.getServletContext().getRealPath("/") + "upload\";

//获取上传文件存储路径

File file = new File(temp);

//创建文件对象

if(!file.exists())
file.mkdirs();

//如果临时目录不存在，则创建该目录

try {
upload.upload(file);
response.getWriter().write(upload.getFileItem().getName());
} catch(org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e){
//文件大小超过限制
e.printStackTrace();
}catch (Exception e){
e.printStackTrace();
}

//上传文件，将文件存储到指定路径下，返回文件名

return null;

//返回null值，表示上传完成，不进行页面跳转

}

}

//类UploadAction结束