How to set a progress bar when downloading a file using struts2 and Ajax

Question

I can’t put a progress bar because it directly redirects the page and the file loads.

Answer 1

So many questions (most of them implicitly) in one!

How to set a progress bar when downloading a file using struts2 and Ajax

• Do not use the AJAX download if it is not needed. When you open the file in a browser ( contentDisposition: inline), just use the new tab (/ Window). When you upload a file ( contentDisposition: attachment), the current page will not be affected. You can find several ways to do this in this answer , for example:

  <s:url action="downloadAction.action" var="url">
      <s:param name="param1">value1</s:param>
  </s:url>
  <s:a href="%{url}" >download</s:a>
  

How can we put the browser progress bar?

2. , :

   

   , . , contentLength, Stream:

   <result name="success" type="stream">    
       <param name="contentType">image/jpeg</param>
       <param name="contentDisposition">attachment;filename="document.pdf"</param>
       <param name="contentLength">${lengthOfMyFile}</param>
   </result>
   

   private long lengthOfMyFile; // with Getter
   
   public String execute(){
       /* file loading and stuff ... */
       lengthOfMyFile = myFile.length();
       return SUCCESS;
   }
   

, . , ,

3. , -. :

   , , , , . , , :

   // The Action must implement the SessionAware interface
   
   private Map<String,Object> session; // with Setter
   private final static String BUSY = "I'm busy. Try again";
   
   public String execute(){
       if (session.get(BUSY)!=null){
          LOG.debug("Another download is in progress. I stop here");
          return NONE;
       }
       try {
           session.put(BUSY,BUSY);
           /* file loading and stuff ... */
       } finally {
           session.remove(BUSY);
           return SUCCESS;
       }
   }
   

   .