I am trying to make the user able to download a file
<h:commandLink value="yes" actionListener="#{Bean.readFileFromServer}"/>
the method redFileFromServer is a method that returns void, it does some logic then it calls anthoer method to return the file to the response
public void exportList() throws IOException {
FacesContext fc = FacesContext.getCurrentInstance();
fc = FacesContext.getCurrentInstance();
ExternalContext ec = fc.getExternalContext();
ec.responseReset();
try {
userLogger.info("Exposting report ");
ec.setResponseContentType("application/octet-stream"); // Check
ec.setResponseHeader("Content-Disposition", "attachment; filename=\"" + result.getFileName() + "\"");
OutputStream output = ec.getResponseOutputStream();
int octet;
while ((octet = input.read()) != -1) {
output.write(octet);
}
input.close();
output.close();
fc.responseComplete();
} catch (Exception e) {
e.printStackTrace();
}
}
the file downloaded is compressed zip file, I have 2 problems, first sometimes this works and sometimes not, and I don't know why the behavior is not consistence.Second problem if there is any exception the page is redirected, which is unacceptable duo to my structure design, I need this to work every time and in case of any problem the page won't redirect.
Related
REQUEST :
URL: http://localhost:8080/RESTfulExample/rest/file/upload
METHOD : POST
HEADER: Content-Type : multipart/form-data
RESPONSE :
HTTP Status 400 - Bad Request
The same code is working with html forms but in postman it's throwing 400 BAD REQUEST, I looked up on google for solution and found that boundary is missing, How to resolve it ? As I have to recieve files from multiple clients like mobile application and web clients via Jquery and rest client.
#Path("/file")
public class UploadFileService {
#POST
#Path("/upload")
#Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadFile(#FormDataParam("file") InputStream uploadedInputStream,
#FormDataParam("file") FormDataContentDisposition fileDetail) {
try {
String uploadedFileLocation = "/home/nash/" + fileDetail.getFileName();
// save it
writeToFile(uploadedInputStream, uploadedFileLocation);
String output = "File uploaded to : " + uploadedFileLocation;
System.out.println("File uploaded..........");
return Response.status(200).entity(output).build();
} catch (Exception e) {
e.printStackTrace();
System.out.println("Exception " + e);
return null;
}
}
// save uploaded file to new location
private void writeToFile(InputStream uploadedInputStream, String uploadedFileLocation) {
try {
OutputStream out = new FileOutputStream(new File(uploadedFileLocation));
int read = 0;
byte[] bytes = new byte[1024];
out = new FileOutputStream(new File(uploadedFileLocation));
while ((read = uploadedInputStream.read(bytes)) != -1) {
out.write(bytes, 0, read);
}
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Please follow these steps:
Add jersey-multipart dependency.
In Your Application Class (or in web.xml) enable MultipartFeature.class.
DO NOT Add Content-Type header in your postman request.
For me the above steps worked. Do let me know if that helped you or not.
I have created a dynamic web project in eclipse.
It contains a Servlet ResidentApi.java and two java classes:GeoLocationDemo.java and Geolocation.java. I am calling GeoLocationDemo.java from my servlet and getting result in a ResultSet.But i am not getting any value in ResultSet.
When i ran same GeoLocationDemo.java separatly i am getting right results.I don't know servlet is able to call my java class or not but if it is then why i am not getting results.
I am having hard time debugging it.What i am doing is running .war file of this project every time on tomcat server and checking results there.Please suggest a good method to test it on eclipse.
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html");
PrintWriter out = response.getWriter();
ResultSet rs = null;
try{
GeoLocationDemo geo = new GeoLocationDemo(); //Here i created a new object
rs = geo.getResults(); //here i called a method of GeoLocation
}catch(Exception e){
// System.out.println(e);
out.write("<head><b You suck</b></head>");
}
out.write("<head><b>Congratulation! connected</b></head>"); //i am getting this output
try{
while(rs.next()){
String s = rs.getString("Details");
out.write("<head><b> "+s+ " </b></head>"); //not able to get this output
}
}catch(Exception e){
// System.out.println(e);
out.write("<head><b>You Built </b></head>");
}
out.close();
}
Don't put everything in a <head> tag! Open a body somewhere. Don't silently swallow any Exception you might be getting. Do remember to close() the ResultSet. Also, you should probably be returning all of your data in a List with a POJO.
out.write("<body>");
out.write("<b>Congratulation! connected</b><br/>");
try {
while (rs.next()) {
String s = rs.getString("Details");
out.write("<b> "+s+ "</b><br/>");
}
} catch (Exception e){
// System.out.println(e);
out.write("<b>" + e.getMessage() + "</b>");
e.printStackTrace(out);
} finally {
try {
out.close();
} catch (Exception ignored) {
}
try {
rs.close();
} catch (Exception ignored) {
}
}
configure remote debugging between your IDE and Tomcat server e.g. take a look on Remote debugging Tomcat with Eclipse
localize the problem - is the problem in GeoLocationDemo or in ResultSet or in output processing
p.s. do not close resources you never open - out.close(); - it is managed by servlet container
I'm working on a functionality in my asp.net web site that enables the user to download some files as a zip file. I'm using the DotNetZip library to generate the zip file.
My code looks like this:
protected void OkbtnZipExport_OnClickEvent(object sender, EventArgs e)
{
var selectedDocumentIds = GetSelectedDocIds();
string archiveName = String.Format("archive-{0}.zip", DateTime.Now.ToString("yyyy-MMM-dd-HHmmss"));
AddResponseDataForZipFile(Response, archiveName);
try
{
string errorMessage = Utils.ExportToZip(selectedDocumentIds, arkivdelSearchControl.GetbraArkivConnection(), Response.OutputStream);
if (!string.IsNullOrEmpty(errorMessage))
{
LiteralExportStatus.Text = errorMessage;
}
else
LiteralExportStatus.Text = "Success";
}
catch (Exception ex)
{
LiteralExportStatus.Text = "Failure " + ex.Message;
}
Response.Flush();
Response.Close();
HttpContext.Current.ApplicationInstance.CompleteRequest();
}
private void AddResponseDataForZipFile(HttpResponse response, string zipName)
{
Response.Clear();
Response.BufferOutput = false;
Response.ContentType = "application/x-zip-compressed";
Response.AddHeader("content-disposition", "attachment; filename=" + zipName);
Response.AddHeader("Expires", "0");
Response.AddHeader("Content-Description", "Zip Arcive");
}
Now, if anything goes wrong, say the Utils.ExportToZip method fails, I want to present an error message to the user and not the download dialog. Do I have to remove some data from the Response object in order to cancel the download operation?
Best regards
OKB
first, Don't call HttpContext.Current.ApplicationInstance.CompleteRequest();
Reference.
At one point, there was some example code that showed CompleteRequest(), but it's wrong.
Second - to do what you describe,
you'll need to insure that the zip file can be created correctly and in its entirety, before sending anything. That means you should do the AddResponseDataForZipFile() only after the zipfile is completely created. That means you need to create an actual zip file on the server, and not simply save out to Response.OutputStream. Once the file is successfully created, then call AddResponseDataForZipFile(), stream the bytes for the temp zip file, call Response.Close(), then delete the temporary zip file.
I can't comment at the moment, so take this answer as one.
How does Utils.ExportToZip work?
If the reason it takes the Response.OutputStream for the constructor is to write the zip-file directly into it, then you need to set Buffering in order to "undo" that in your AddResponseDataForZipFile Method:
Response.BufferOutput = true;
I have an Excel file on the server side. How I can display it on client side browser using servlets?
Thanks in advance.
To the point: just get an InputStream of it somehow (FileInputStream is suitable) and write it to the OutputStream of the response the usual Java IO way. That's basically all. You'll only need to take care that you set the right response headers, so that the browser understands what to do with it. The Content-Type header will instruct the webbrowser what kind of file it is so that the browser knows which application to use to open it.
Here's a kickoff example:
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String filename = URLDecoder.decode(request.getPathInfo(), "UTF-8");
File file = new File("/path/to/files", filename);
response.setHeader("Content-Type", getServletContext().getMimeType(file.getName()));
response.setHeader("Content-Length", file.length());
response.setHeader("Content-Disposition", "inline; filename=\"" + file.getName() + "\"");
BufferedInputStream input = null;
BufferedOutputStream output = null;
try {
input = new BufferedInputStream(new FileInputStream(file));
output = new BufferedOutputStream(response.getOutputStream());
byte[] buffer = new byte[8192];
for (int length = 0; (length = input.read(buffer)) > 0;) {
output.write(buffer, 0, length);
}
} finally {
if (output != null) try { output.close(); } catch (IOException ignore) {}
if (input != null) try { input.close(); } catch (IOException ignore) {}
}
}
Map this servlet in web.xml on an url-pattern of /files/* so that you can get the excel file by http://example.com/contextname/files/filename.xls.
If it's actually an xlsx file, which isn't by default recognized by the average servletcontainer yet (the ServletContext#getMimeType() would then return application/octet-stream instead of the desired xlsx content type), then you need to add the following entry to the web.xml as well:
<mime-mapping>
<extension>xlsx</extension>
<mime-type>application/vnd.openxmlformats-officedocument.spreadsheetml.sheet</mime-type>
</mime-mapping>
For a more advanced example of a file servlet you may find this article useful as well, it supports under each download resumes as well.
Any ideas why on some links that I try to access using HttpWebRequest I am getting "The remote server returned an error: (304) Not Modified." in the code?
The code I'm using is from Jeff's post here (the page seems to have disappeared, see an archive copy at the Wayback Machine).
Note the concept of the code is a simple proxy server, so I'm pointing my browser at this locally running piece of code, which gets my browsers request, and then proxies it on by creating a new HttpWebRequest, as you'll see in the code. It works great for most sites/links, but for some this error comes up. You will see one key bit in the code is where it seems to copy the http header settings from the browser request to it's request out to the site, and it copies in the header attributes. Not sure if the issue is something to do with how it mimics this aspect of the request and then what happens as the result comes back?
case "If-Modified-Since":
request.IfModifiedSince = DateTime.Parse(listenerContext.Request.Headers[key]);
break;
I get the issue for example from http://en.wikipedia.org/wiki/Main_Page
PS. UPDATE HERE
Still can't work this out. Basically I can identify 1 link which has an issue, and it seems to work fine, 2nd time it gets the error, 3rd time OK, 4th time gets the error, 5th time OK etc. As if there is some state not getting cleared or something in the code. I've tried to clean up the code a bit using "using" type statements etc.
Here's the code. If anyone can spot why every 2nd time I browse to a link like http://newsimg.bbc.co.uk/css/screen/1_0_16/nol/v4/story.css (starting at the 2nd time, not the first) via this proxy code I get the error I'd love to hear.
class Program
{
static void Main(string[] args)
{
Proxy p = new Proxy(8080);
Thread proxythread = new Thread(new ThreadStart(p.Start));
proxythread.Start();
Console.WriteLine("Proxy Started. Press Any Key To Stop...");
Console.ReadKey();
p.Stop();
}
}
public class Proxy
{
private HttpListener _listener;
private int _port;
public Proxy(int port)
{
int defaultport = 8080;
// Setup Thread Pool
System.Threading.ThreadPool.SetMaxThreads(50, 1000);
System.Threading.ThreadPool.SetMinThreads(50, 50);
// Sanitize Port Number
if (port < 1024 || port > 65535)
port = defaultport;
// Create HttpListener Prefix
string prefix = string.Format("http://*:{0}/", port);
_port = port;
// Create HttpListener
_listener = new HttpListener();
_listener.Prefixes.Add(prefix);
}
public void Start()
{
_listener.Start();
while (true)
{
HttpListenerContext request = null;
try
{
request = _listener.GetContext();
// Statistics (by Greg)
int availThreads = -1;
int compPortThreads = -1;
ThreadPool.GetAvailableThreads(out availThreads, out compPortThreads);
log("INFO", request.Request.Url.ToString(), "START - [" + availThreads + "]");
ThreadPool.QueueUserWorkItem(ProcessRequest, request);
}
catch (HttpListenerException ex)
{
log("ERROR", "NA", "INFO: HttpListenerException - " + ex.Message);
break;
}
catch (InvalidOperationException ex)
{
log("ERROR", "NA", "INFO: InvalidOperationException - " + ex.Message);
break;
}
}
}
public void Stop()
{
_listener.Stop();
}
private void log(string sev, string uri, string message)
{
Console.Out.WriteLine(Process.GetCurrentProcess().Id + " - " + sev + " (" + uri + "): " + message);
}
private void ProcessRequest(object _listenerContext)
{
#region local variables
HttpWebRequest psRequest; // Request to send to remote web server
HttpWebResponse psResponse; // Response from remote web server
List<byte> requestBody = new List<byte>(); // Byte array to hold the request's body
List<byte> responseBody = new List<byte>(); // Byte array to hold the response's body
byte[] buffer;
string uri = "";
#endregion
var listenerContext = (HttpListenerContext)_listenerContext;
uri = listenerContext.Request.Url.ToString().Replace(string.Format(":{0}", _port), "");
// Create Interent Request
HttpWebRequest internetRequest = (HttpWebRequest)WebRequest.Create(uri);
#region Build Request Up
internetRequest.Method = listenerContext.Request.HttpMethod;
internetRequest.ProtocolVersion = listenerContext.Request.ProtocolVersion;
internetRequest.UserAgent = listenerContext.Request.UserAgent;
foreach (string key in listenerContext.Request.Headers.AllKeys)
{
try
{
switch (key)
{
case "Proxy-Connection":
case "Connection":
internetRequest.KeepAlive = (listenerContext.Request.Headers[key].ToLower() == "keep-alive") ? true : false;
break;
case "Content-Length":
internetRequest.ContentLength = listenerContext.Request.ContentLength64;
break;
case "Content-Type":
internetRequest.ContentType = listenerContext.Request.ContentType;
break;
case "Accept":
internetRequest.Accept = listenerContext.Request.Headers[key];
break;
case "Host":
break;
case "Referer":
internetRequest.Referer = listenerContext.Request.Headers[key];
break;
case "If-Modified-Since":
internetRequest.IfModifiedSince = DateTime.Parse(listenerContext.Request.Headers[key]);
break;
default:
internetRequest.Headers.Add(key, listenerContext.Request.Headers[key]);
break;
}
}
catch (Exception ex)
{
Console.WriteLine("Error settup up psRequest object. Error = " + ex.Message + "\n" + ex.StackTrace);
}
}
#endregion
#region Copy content into request
buffer = new byte[1024];
using (Stream instream = listenerContext.Request.InputStream)
{
int incount = instream.Read(buffer, 0, buffer.Length);
while (incount > 0)
{
internetRequest.GetRequestStream().Write(buffer, 0, incount);
incount = instream.Read(buffer, 0, buffer.Length);
}
}
#endregion
// Get Internet Response
HttpWebResponse internetResponse = null;
try
{
using (internetResponse = (HttpWebResponse)internetRequest.GetResponse())
{
#region Configure Local Response Header Keys
foreach (string key in internetResponse.Headers.Keys)
{
try
{
switch (key)
{
case "Transfer-Encoding":
listenerContext.Response.SendChunked = (internetResponse.Headers[key].ToLower() == "chunked") ? true : false;
break;
case "Content-Length":
listenerContext.Response.ContentLength64 = internetResponse.ContentLength;
break;
case "Content-Type":
listenerContext.Response.ContentType = internetResponse.Headers[key];
break;
case "Keep-Alive":
listenerContext.Response.KeepAlive = true;
break;
default:
listenerContext.Response.Headers.Add(key, internetResponse.Headers[key]);
break;
}
}
catch (Exception ex)
{
log("ERROR", uri, "Error settup up listenerContext.Response objects. Error = " + ex.Message + "\n" + ex.StackTrace);
}
}
#endregion
try
{
// Transfer the body data from Internet Response to Internal Response
buffer = new byte[1024];
using (Stream inputStream = internetResponse.GetResponseStream())
{
int outcount = inputStream.Read(buffer, 0, buffer.Length);
while (outcount > 0)
{
listenerContext.Response.OutputStream.Write(buffer, 0, outcount);
outcount = inputStream.Read(buffer, 0, buffer.Length);
}
}
}
catch (Exception ex)
{
log("ERROR", uri, "Could not obtain response from URI: " + ex.Message);
}
finally
{
listenerContext.Response.OutputStream.Close();
}
}
}
catch (Exception ex)
{
//if (ex is InvalidOperationException ||
// ex is ProtocolViolationException ||
// ex is WebException)
//{
// log(uri, "Could not successfully get response: " + ex.GetType() + " - " + ex.Message);
// listenerContext.Response.Close();
// return;
//}
//else { throw; }
log("ERROR", uri, "Could not successfully get response: " + ex.GetType() + " - " + ex.Message);
listenerContext.Response.Close();
}
}
}
And here is an example of what I see - first hit is good, 2nd has error...
Proxy Started. Press Any Key To Stop...
2080 - INFO (http://newsimg.bbc.co.uk:8080/css/screen/1_0_16/nol/v4/story.css): START - [50]
2080 - INFO (http://newsimg.bbc.co.uk:8080/css/screen/1_0_16/nol/v4/story.css): START - [50]
2080 - ERROR (http://newsimg.bbc.co.uk/css/screen/1_0_16/nol/v4/story.css): Could not successfully get response: System.Net.WebException - The remote server returned an error: (304) Not Modified.
First, this is not an error. The 3xx denotes a redirection. The real errors are 4xx (client error) and 5xx (server error).
If a client gets a 304 Not Modified, then it's the client's responsibility to display the resouce in question from its own cache. In general, the proxy shouldn't worry about this. It's just the messenger.
This is intended behavior.
When you make an HTTP request, the server normally returns code 200 OK. If you set If-Modified-Since, the server may return 304 Not modified (and the response will not have the content). This is supposed to be your cue that the page has not been modified.
The authors of the class have foolishly decided that 304 should be treated as an error and throw an exception. Now you have to clean up after them by catching the exception every time you try to use If-Modified-Since.
Just pressing F5 is not always working.
why?
Because your ISP is also caching web data for you.
Solution: Force Refresh.
Force refresh your browser by pressing CTRL + F5 in Firefox or Chrome to clear ISP cache too, instead of just pressing F5
You then can see 200 response instead of 304 in the browser F12 developer tools network tab.
Another trick is to add question mark ? at the end of the URL string of the requested page:
http://localhost:52199/Customers/Create?
The question mark will ensure that the browser refresh the request without caching any previous requests.
Additionally in Visual Studio you can set the default browser to Chrome in Incognito mode to avoid cache issues while developing, by adding Chrome in Incognito mode as default browser, see the steps (self illustrated):
It is not an issue it is because of caching...
To overcome this add a timestamp to your endpoint call, e.g. axios.get('/api/products').
After timestamp it should be axios.get(/api/products?${Date.now()}.
It will resolve your 304 status code.
I think you have not installed these features. see below in picture.
I also suffered from this problem some days ago. After installing this feature then I solved it. If you have not installed this feature then installed it.
Install Process:
go to android studio
Tools
Android
SDK Manager
Appearance & Behavior
Android SDK