File downloading alert in jsp

Question

I am using the following code in jsp to download a file from the server. I am using the struts framework. I want to display an alert message if the file is not present(with the following code, if the file is not present it is downloaded in an unreadable format). I am not sure how to implement that. Would really appreciate if someone helps on this.

jsp contents:

<a href='<%=url%>/download.jsp?Path=<%=filePath%>&fileName=${CustomerRegistrationForm.customerId}_certificate.pdf' style="text-decoration:none"><font color="#0000FF">Click Here</font></a>

I want to implement it in the same jsp page. – Biswajit das Nov 05 '12 at 05:13 — Biswajit das, Nov 05 '12 at 05:13

Konza · Answer 1 · 2012-11-05T13:32:35.230

On clicking the url instead of an href send an ajax request. and check for the response status if its 200 that means the file is there and it can be downloaded. If the file is not there you will get a 404 error status. in that case you can alert the message.

<body>
    <script language="javascript" type="text/javascript">
        function ajaxFunction(){
            var ajaxRequest;  // The variable that makes Ajax possible!
            try{
                // Opera 8.0+, Firefox, Safari
                ajaxRequest = new XMLHttpRequest();
            } catch (e){
                // Internet Explorer Browsers
                try{
                    ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
                } catch (e) {
                    try{
                        ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
                    } catch (e){
                        // Something went wrong
                        alert("Your browser broke!");
                        return false;
                    }
                }
            }
            // Create a function that will receive data sent from the server
            ajaxRequest.onreadystatechange = function(){
                if(ajaxRequest.readyState == 4){
                    if(ajaxRequest.status == 200)   {
                    alert("File Found");
                    document.getElementById("downloadIframe").src = "abc.csv";
                    }
                    else    
                        alert("File Not Found");


                }
            }
            ajaxRequest.open("GET", "abc.csv", true);
            ajaxRequest.send(null); 
        }

    </script>
    <input type = "button" onclick = "ajaxFunction()" value =  "Download"/>
    <iframe id =  "downloadIframe" src =""  style="display:none;"></iframe>
</body>

Thanks Konza. Actually I dont have any idea about ajax. I am using only jsp, html and java. Not sure how to implement the above code in the code code i mentioned above. If possible please give me the complete code. — Biswajit das, Nov 05 '12 at 08:48
try this link.. Its very very easy.. there is nothing much to learn.. http://www.tizag.com/ajaxTutorial/ — Konza, Nov 05 '12 at 09:08
@Biswajitdas - I have edited the answer. Please go through it. Its a working example... Hope this helps you. — Konza, Nov 05 '12 at 13:33

File downloading alert in jsp

1 Answers1