I am trying to let the user save data from my servlet as a CSV file. Originally I was just locating their desktop to drop the file, but permission would be denied with this route so I want to ask the user where they want to save it.
From what I am seeing, I cannot use the Swing API in a servlet because Tomcat does not know how to draw the GUI. I tried this code:
String fileName = "ClassMonitor" + formatter.format(currentDate) + ".csv";
File csvFile = new File(fileName);
//Attempt to write as a CSV file
try{
JFileChooser fileChooser = new JFileChooser();
fileChooser.setSelectedFile(csvFile);
int returnValue = fileChooser.showSaveDialog(null);
if(returnValue == JFileChooser.APPROVE_OPTION)
{
BufferedWriter out = new BufferedWriter(new FileWriter(csvFile));
//Iterates and writes to file
for(ClassInfo classes : csvWrite)
{
//Check if the class has a comma. Currently, only section titles have a comma in them, so that's all we check for.
classes.setSectionTitle(replaceComma(classes.getSectionTitle()));
out.write(classes.toString());
}
//Close the connection
out.close();
}
//Log the process as successful.
logger.info("File was successfully written as a CSV file to the desktop at " + new Date() + "\nFilename" +
"stored as " + fileName + ".");
}
catch(FileNotFoundException ex)
{
//Note the exception
logger.error("ERROR: I/O exception has occurred when an attempt was made to write results as a CSV file at " + new Date());
}
catch(IOException ex)
{
//Note the exception
logger.error("ERROR: Permission was denied to desktop. FileNotFoundException thrown.");
}
catch(Exception ex)
{
//Note the exception
logger.error("ERROR: Save file was not successfull. Ex: " + ex.getMessage());
}
}
But this will throw a headlessException.
Any guidance on how to implement something like a save file dialog in a servlet would be appreciated.
Just write it to the response body instead of to the local(!!) disk file system.
response.setContentType("text/csv"); // Tell browser what content type the response body represents, so that it can associate it with e.g. MS Excel, if necessary.
response.setHeader("Content-Disposition", "attachment; filename=name.csv"); // Force "Save As" dialogue.
response.getWriter().write(csvAsString); // Write CSV file to response. This will be saved in the location specified by the user.
The Content-Disposition: attachment header takes care of the Save As magic.
See also:
JSP generating Excel spreadsheet (XLS) to download
You can't call the JFileChooser from the servlet because the servlet runs on the server, not on the client; all of your Java code is executed on the server. If you want to save the file on the server, you need to already know the path you want to write to.
If you want to prompt the user's browser to save the file, use the content-disposition header: Uses of content-disposition in an HTTP response header
Related
We are currently using the EasyUpload add-on, and we have specified the criteria for this component:
a) only CSV files are allowed, with a cap size of 1MB per file.
b) only one file can be submitted at a time.
We just did an uploading test on small-sized CSV files that are below 100Kb. Usually, the upload process completes successfully. Occasionally, the error of "Could not open file, The system cannot find the file specified" is displayed although the file is already inside the temp folder, and we found that this happens either when:
a) If the same file is uploaded again after making a small change and within a few seconds after the file has been uploaded successfully.
b) If there are two tabs of the web app, logged under different users were uploading their respective csv files and they also do the same thing of changing values in the csv before uploading them again.
We tried forcing the file upload through (as another testing method) and noticed after a while that the files sometimes get stuck in the queue although we have imposed a one file at a submission time rule. It was displayed in a message "There are too many files over the count limit". We also considered of putting a sleep / wait command of 3-5 seconds after the file submission.
MultiFileUpload multiFileUpload = new MultiFileUpload() {
#Override
protected void handleFile(File tmpFile, String fileName, String mimeType, long length) {
String[] header = {"EOD_NUM","OUTLET_NAME","POSM_NAME","EOD_DATE","TOTAL_SALES","GROSS_SALES",
"TRAN_COUNT","VOID_COUNT","SERVICE_CHARGE","DISCOUNT_AMT","VAT_TAX_AMT","SVC_TAX_AMT","ROUNDING_ADJ"};
uploadLogger.debug("File: " + tmpFile.getAbsolutePath());
uploadLogger.debug("FileName: " + fileName);
uploadLogger.debug("MimeType: " + mimeType);
uploadLogger.debug("File Length: " + length);
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("ddMMyyyyHHmmss");
LocalDateTime now = LocalDateTime.now();
File f2 = null;
f2 = new File(busId+"_"+dtf.format(now)+".csv");
tmpFile.renameTo(f2);
try {
///var/lib/tomcat8/ in linux
///D:\\home\\site\\wwwroot\\ in Windows
uploadLogger.debug("f2 absolutepath: " + f2.getAbsolutePath());
uploadLogger.debug("f2 canonical path: " + f2.getCanonicalPath());
CloudBlockBlob blob = container.getBlockBlobReference(f2.getName());
if(f2.length() > 0){
blob.uploadFromFile(f2.getAbsolutePath());
Notification.show("File upload completed.",Notification.Type.TRAY_NOTIFICATION);
}
CSVReader reader = new CSVReader(new FileReader(f2.getAbsolutePath()), ',' , '"' , 0);
//read header name
//String[] myheader = reader.readNext();
//NOTE :: Store all row and column from csv info List of String Array
myEntries = reader.readAll();
if (myEntries != null && !myEntries.isEmpty()) {
boolean success = uploadDAO.insertUploaderEntry(myEntries,busId, userId,"");
uploadLogger.debug("SUCCESSS??? " + success);
if(success){
Notification successNotify = new Notification("Record has been created successfully.","Upload Successful!");
successNotify.setDelayMsec(3000);
successNotify.setStyleName(ValoTheme.NOTIFICATION_SUCCESS);
successNotify.setPosition(Position.MIDDLE_CENTER);
successNotify.show(Page.getCurrent());
}else {
Notification.show("Error in submitting uploaded record.","Upload failed!"
, Notification.Type.ERROR_MESSAGE).setDelayMsec(3000);
}
Thread.sleep(3000); //added to see if the delay solves the problem or not.
}
} catch (URISyntaxException | StorageException | IOException ex) {
new Notification("Could not open file",ex.getMessage(),Notification.Type.ERROR_MESSAGE).show(Page.getCurrent());
uploadLogger.debug(ex);
} catch (InterruptedException ix) {
uploadLogger.debug("Interrupted Exception found: " + ix.getMessage());
}
}
#Override
protected boolean supportsFileDrops() {
return false;
}
};
multiFileUpload.setMaxFileCount(1);
multiFileUpload.setUploadButtonCaption("Upload CSV file here");
multiFileUpload.setMaxFileSize(fileSizeLimit); // 2MB
multiFileUpload.setAcceptFilter(".csv");
We are unsure whether if this problem is a known limitation of the component or not.
Some of the questions we have discovered along the way are:
a) Is there a better way or to control on the file uploading and to avoid the open file / file not found error?
b) Are the values in the setAcceptedFilter method the mime/type values or something else. We noticed for images, it's "images/*" but for csv, we had to put in as ".csv"
Answering to your second question. The acceptFilter is directly passed to upload inputs "accept" attribute, so both .csv and text/csv should do fine. See https://www.w3schools.com/tags/att_input_accept.asp for more instructions.
I create a test html file on an Android (7.0) device from string content. File is created fine, shows up with right extension and icon, but format isn't recognized when tapped, giving message "file format is not supported". Yet, if I save this same file to PC and transfer back to device, the issue disappears. It then shows app choices to open html, as it should be.
Tried several write methods. In all cases file was created and content looked right, but format wasn't recognized rightaway. Can't figure out why, is there an extra step or written data required for this? The latest one was with BufferedWriter (to ensure UTF-8) as below:
final File file = new File(path, name + file_extension);
StringBuilder strBuilder = new StringBuilder();
strBuilder.append("test");
strBuilder.insert(0, "<html>"+"\r\n"+"<body><p>"+"\r\n");
strBuilder.insert(strBuilder.length(), "\r\n"+"</p></body>"+"\r\n"+ "</html>");
String html_content=strBuilder.toString();
try
{
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8));
bw.write(html_content);
bw.close();
} catch (IOException e)
{
e.printStackTrace();
Log.e("Exception", "File write failed: " + e.toString());
}
Try to add this before your HTML Tags:
<!DOCTYPE html>
and delete the StringBuilder.append("test");
I followed the discussion on spark github page as well as stack overflow to understand how to upload files using spark and apache file uploads.
Now I want the user to have an option to download the image on click.
For example my uploaded files get stored in /tmp/imageName.jpg on the server.
On the client side i want to give the user an option to download the file when the user clicks in the hyperlink.
click here
When the user click on the hyperlink I will call the function with the file path but can't understand how to send the image in response.
I do know that HTML5 has download attribute but that would require the files to be kept in public folder on the server which is not possible.
I went through the previous similar question add tried to replicate for my scenario without success
How can I send a PNG of a QR-code in a HTTP response body (with Spark)?
How download file using java spark?
Edit:
I did follow the link provided in the answer to force download the image, but using response.raw() i'm not able to get the response
response.type("application/force-download");
response.header("Content-Transfer-Encoding", "binary");
response.header("Content-Disposition","attachment; filename=\"" + "xxx\"");//fileName);
try {
HttpServletResponse raw = response.raw();
PrintWriter out = raw.getWriter();
File f= new File("/tmp/Tulips.jpg");
InputStream in = new FileInputStream(f);
BufferedInputStream bin = new BufferedInputStream(in);
DataInputStream din = new DataInputStream(bin);
while(din.available() > 0){
out.print(din.read());
out.print("\n");
}
}
catch (Exception e1) {
e1.printStackTrace();
}
response.status(200);
return response.raw();
Edit 2:
I'm not sure what is the difference between using response.body () vs response.raw().someFunction(). In either case I can seem to send the data back in response. Even if i write a simple response.body("hello") it doesn't reflect in my response.
Is there a difference in how a file would be read as opposed to an image ? Exampling using ImageIO class ?
Below is the solution that work for me:
Service.java
get(API_CONTEXT + "/result/download", (request, response) -> {
String key = request.queryParams("filepath");
Path path = Paths.get("/tmp/"+key);
byte[] data = null;
try {
data = Files.readAllBytes(path);
} catch (Exception e1) {
e1.printStackTrace();
}
HttpServletResponse raw = response.raw();
response.header("Content-Disposition", "attachment; filename=image.jpg");
response.type("application/force-download");
try {
raw.getOutputStream().write(data);
raw.getOutputStream().flush();
raw.getOutputStream().close();
} catch (Exception e) {
e.printStackTrace();
}
return raw;
});
Angular Code
$scope.downloadImage= function(filepath) {
console.log(filepath);
window.open('/api/v1/result/download?filepath='+filepath,'_self','');
}
I get how you can use Expression Language to bind XPages controls to a Java Bean. Then it accesses the setters and getters automatically.
But how do you handle a file attachment?
What does that look like? I'd like to be able to I guess bind the file upload control to the bean. Save the attachment to "whatever" doc... whether it's the current or external document.. the bean should be able to handle that logic.
I guess I don't know how to get that file attachment into the in memory bean to be able to do anything with it like saving to a document.
any advice would be appreciated.
Update: This is a similar question to this: How to store uploaded file to local file system using xPages upload control?
But in that question the user wants to save to local disc. I'm looking to save to a document.
Thanks!
You need to create a getter and setter in the bean using the com.ibm.xsp.component.UIFileuploadEx.UploadedFile class:
private UploadedFile uploadedFile;
public UploadedFile getFileUpload() {
return uploadedFile;
}
public void setFileUpload( UploadedFile to ) {
this.uploadedFile = to;
}
In the function that processes the bean data (e.g. a save function) you can check if a file was uploaded by checking if the object is null. If it's not null, a file was uploaded.
To process that uploaded file, first get an instance of a com.ibm.xsp.http.IUploadedFile object using the getServerFile() method. That object has a getServerFile() method that returns a File object for the uploaded file. The problem with that object is that it has a cryptic name (probably to deal with multiple people uploading files with the same name at the same time). The original file name can be retrieved using the getClientFileName() method of the IUploadedFile class.
What I then tend to do is to rename the cryptic file to its original file name, process it (embed it in a rich text field or do something else with it) and then rename it back to its original (cryptic) name. This last step is important because only then the file is cleaned up (deleted) after the code is finished.
Here's the sample code for the steps above:
import java.io.File;
import com.ibm.xsp.component.UIFileuploadEx.UploadedFile;
import com.ibm.xsp.http.IUploadedFile;
import lotus.domino.Database;
import lotus.domino.Document;
import lotus.domino.RichTextItem;
import com.ibm.xsp.extlib.util.ExtLibUtil; //only used here to get the current db
public void saveMyBean() {
if (uploadedFile != null ) {
//get the uploaded file
IUploadedFile iUploadedFile = uploadedFile.getUploadedFile();
//get the server file (with a cryptic filename)
File serverFile = iUploadedFile.getServerFile();
//get the original filename
String fileName = iUploadedFile.getClientFileName();
File correctedFile = new File( serverFile.getParentFile().getAbsolutePath() + File.separator + fileName );
//rename the file to its original name
boolean success = serverFile.renameTo(correctedFile);
if (success) {
//do whatever you want here with correctedFile
//example of how to embed it in a document:
Database dbCurrent = ExtLibUtil.getCurrentDatabase();
Document doc = dbCurrent.createDocument();
RichTextItem rtFiles = doc.createRichTextItem("files");
rtFiles.embedObject(lotus.domino.EmbeddedObject.EMBED_ATTACHMENT, "", correctedFile.getAbsolutePath(), null);
doc.save();
rtFiles.recycle();
doc.recycle();
//if we're done: rename it back to the original filename, so it gets cleaned up by the server
correctedFile.renameTo( iUploadedFile.getServerFile() );
}
}
}
I have code that processes an uploaded file in Java. The file is uploaded with the normal fileUpload control and then I call the following Java code from a button (that does a full refresh - so that the document including the uploaded file is saved). In the Java code you can do whatever checks you want (filename, filesize etc.):
public void importFile() {
facesContext = FacesContext.getCurrentInstance();
ExternalContext externalContext = facesContext.getExternalContext();
// get a handle an the uploaded file
HttpServletRequest request = (HttpServletRequest) externalContext.getRequest();
String fileUploadID = JSFUtil.findComponent("uploadFile").getClientId(FacesContext.getCurrentInstance());
UploadedFile uploadedFile = ((UploadedFile) request.getParameterMap().get(fileUploadID));
if (uploadedFile == null) {
facesContext.addMessage("messages1", new FacesMessage(FacesMessage.SEVERITY_ERROR, "No file uploaded. Use the file upload button to upload a file.", ""));
return;
}
File file = uploadedFile.getServerFile();
String fileName = uploadedFile.getClientFileName();
// Check that filename ends with .txt
if (!fileName.endsWith(".txt")) {
facesContext.addMessage("messages1", new FacesMessage(FacesMessage.SEVERITY_ERROR, "Error in uploaded file. The file must end with .txt", ""));
return;
}
try {
// Open the file
BufferedReader br;
br = new BufferedReader(new FileReader(file));
String strLine;
// Read File Line By Line
while ((strLine = br.readLine()) != null) {
// do stuff with the contents of the file
}
// Close the input stream
br.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
facesContext.addMessage("messages1", new FacesMessage(FacesMessage.SEVERITY_ERROR, "Error in uploaded file. Please check format of file and try again", ""));
return;
}
facesContext.addMessage("messages1", new FacesMessage(FacesMessage.SEVERITY_INFO, "File successfully uploaded", ""));
}
With a handle on the file object you can store the file in other documents using embedObject.
I need to store and retrieve MS Word documents into MySQL 5.1 with Servlets. I've the code to upload a file, but I don't know can I feed into the table. I've used BLOB for the field I've to insert .doc files.
Here's my code snippet to upload files:
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
// get access to file that is uploaded from client
Part p1 = request.getPart("file");
String type=p1.getContentType();
String name=p1.getName();
long size = p1.getSize();
InputStream is = p1.getInputStream();
//FileInputStream fis = is.
// read filename which is sent as a part
Part p2 = request.getPart("name");
Scanner s = new Scanner(p2.getInputStream());
String filename = s.nextLine(); // read filename from stream
// get filename to use on the server
String outputfile = this.getServletContext().getRealPath(filename); // get path on the server
FileOutputStream os = new FileOutputStream (outputfile);
// write bytes taken from uploaded file to target file
int ch = is.read();
while (ch != -1) {
os.write(ch);
ch = is.read();
}
os.close();
out.println("<h3>File : '" + name + "' Type : '" + type + "' "
+ "of Size : " + ((double) size/1024) + "KB uploaded successfully!</h3>");
}
catch(Exception ex) {
out.println("Exception -->" + ex.getMessage());
}
finally {
out.close();
}
}
Here, I've used Servlets 3.0 feature for uploading a file...
My table schema :
resources
- UserID [varchar(15)]
- Document [mediumblob]
Could anyone help me how can I store the document into the table and though BLOB is a type representing binary data, how can I retrieve as a Word Document (*.doc)?
I agree with Archimedix... Instead of putting them into MySQL as BLOB, you can store the file on the disk and store its path in MYSQL as TEXT field. This way your retrieval time will be low. If you are space conscious then you can zip the doc and save it on the disk and on request uncompress and send it.
UPDATE
From your code it appears that you already have the handle of the file and you are able to save it on the server.
Now to save space you can zip it using default java zip utility.
You might face a problem when two people upload two different files with the same name. To avoid scenarios like this you can either rename your archived document with an uuid (use java 6 uuid class) or you can generate SHA1 for that file and use that for name.
Now you can use the absolute path of the archived (and renamed file) for storing in the MySQL.
Instead of table schema
resources
UserID [varchar(15)]
Document [mediumblob]
You can use this
resources
UserID [varchar(15)]
Document [varchar(512)]
So for a query like this:
Select Document from table Documents WHERE UserID = 'abcd';
you will now get an absolute path for the zipped file. Uncompress this file and send it.
A partial answer on storing the Word documents in files:
You don't need any additional column to save the file name as the document's record ID can serve as the file name.
When saving a new document, do in a database transaction so that you can undo the process when something goes wrong.
In pseudo code, this would look like this:
begin transaction;
try {
save new record for document;
save Word document in predefined directory, using record's ID as the filename;
} catch (Exception e) {
rollback transaction;
throw e; // Rethrow exception
}
commit transaction;
The code above assumes that an exception is thrown when an error occurs.