Develop Reference

In Groovy, how to properly get the file from HttpServletRequest

I am writing a REST API in Groovy script that will receive a file upload from client side.
The REST API will receive the file via HttpServletRequest.
I am trying to get the file from HttpServletRequest by getting its InputStream, then convert it to File to save to proper folder.
My code is as below:
RestApiResponse doHandle(HttpServletRequest request, RestApiResponseBuilder apiResponseBuilder, RestAPIContext context) {
InputStream inputStream = request.getInputStream()
def file = new File(tempFolder + "//" + fileName)
FileOutputStream outputStream = null
try
{
outputStream = new FileOutputStream(file, false)
int read;
byte[] bytes = new byte[DEFAULT_BUFFER_SIZE];
while ((read = inputStream.read(bytes)) != -1) {
outputStream.write(bytes, 0, read);
}
}
finally {
if (outputStream != null) {
outputStream.close();
}
}
inputStream.close();
// the rest of the code
}
The files are created, but all of them are corrupted.
When I try to open them with Notepad, all of them have, at the beginning, some thing similar to the below:
-----------------------------134303111730200325402357640857
Content-Disposition: form-data; name="pbUpload1"; filename="Book1.xlsx"
Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
Am I doing this wrong? How do I get the file correctly?

Found the solution with MultipartStream
import org.apache.commons.fileupload.MultipartStream
import org.apache.commons.io.FileUtils
InputStream inputStream = request.getInputStream()
//file << inputStream;
String fileName = "";
final String CD = "Content-Disposition: "
MultipartStream multipartStream = new MultipartStream(inputStream, boundary);
//Block below line because it always return false for some reason
// but should be used as stated in document
//boolean nextPart = multipartStream.skipPreamble();
//Block below line as in my case, the part I need is at the first part
// or maybe I should use it and break after successfully get the file name
//while(nextPart) {
String[] headers = multipartStream.readHeaders().split("\\r\\n")
ContentDisposition cd = null
for (String h in headers) {
if (h.startsWith(CD)) {
cd = new ContentDisposition(h.substring(CD.length()));
fileName = cd.getParameter("filename"); }
}
def file = new File(tempFolder + "//" + fileName)
ByteArrayOutputStream output = new ByteArrayOutputStream(1024)
try
{
multipartStream.readBodyData(output)
FileUtils.writeByteArrayToFile(file, output.toByteArray());
}
finally {
if (output != null) {
output.flush();
output.close();
}
}
inputStream.close();

Blank pages in pdf after downloading it from web

I am trying to download a PDF file with HttpClient, it is downloading the PDF file but pages are blank. I can see the bytes on console from response if I print them. But when I try to write it to file it is producing a blank file.
FileUtils.writeByteArrayToFile(new File(outputFilePath), bytes);
However the file is showing correct size of 103KB and 297KB as expected but its just blank!!
I tried with Output stream as well like:
FileOutputStream fileOutputStream = new FileOutputStream(outFile);
fileOutputStream.write(bytes);
Also tried to write with UTF-8 coding like:
Writer out = new BufferedWriter( new OutputStreamWriter(
new FileOutputStream(outFile), "UTF-8"));
String str = new String(bytes, StandardCharsets.UTF_8);
try {
out.write(str);
} finally {
out.close();
}
Nothing is working for me. Any suggestion is highly appreciated..
Update: I am using DefaultHttpClient.
HttpGet httpget = new HttpGet(targetURI);
HttpResponse response = null;
String htmlContents = null;
try {
httpget = new HttpGet(url);
response = httpclient.execute(httpget);
InputStreamReader dataStream=new InputStreamReader(response.getEntity().getContent());
byte[] bytes = IOUtils.toByteArray(dataStream);
...

You do
InputStreamReader dataStream=new InputStreamReader(response.getEntity().getContent());
byte[] bytes = IOUtils.toByteArray(dataStream);
As has already been mentioned in comments, using a Reader class can damage binary data, e.g. PDF files. Thus, you should not wrap your content in an InputStreamReader.
As your content can be used to construct an InputStreamReader, though, I assume response.getEntity().getContent() returns an InputStream. Such an InputStream usually can be directly used as IOUtils.toByteArray argument.
So:
InputStream dataStream=response.getEntity().getContent();
byte[] bytes = IOUtils.toByteArray(dataStream);
should already work for you!

Here is a method I use to download a PDF file from a specific URL. The method requires two string arguments, an url string (example: "https://www.ibm.com/support/knowledgecenter/SSWRCJ_4.1.0/com.ibm.safos.doc_4.1/Planning_and_Installation.pdf") and a destination folder path to download the PDF file (or whatever) into. If the destination path does not exist within the local file system then it is automatically created:
public boolean downloadFile(String urlString, String destinationFolderPath) {
boolean result = false; // will turn to true if download is successful
if (!destinationFolderPath.endsWith("/") && !destinationFolderPath.endsWith("\\")) {
destinationFolderPath+= "/";
}
// If the destination path does not exist then create it.
File foldersToMake = new File(destinationFolderPath);
if (!foldersToMake.exists()) {
foldersToMake.mkdirs();
}
try {
// Open Connection
URL url = new URL(urlString);
// Get just the file Name from URL
String fileName = new File(url.getPath()).getName();
// Try with Resources....
try (InputStream in = url.openStream(); FileOutputStream outStream =
new FileOutputStream(new File(destinationFolderPath + fileName))) {
// Read from resource and write to file...
int length = -1;
byte[] buffer = new byte[1024]; // buffer for portion of data from connection
while ((length = in.read(buffer)) > -1) {
outStream.write(buffer, 0, length);
}
}
// File Successfully Downloaded");
result = true;
}
catch (MalformedURLException ex) { ex.printStackTrace(); }
catch (IOException ex) { ex.printStackTrace(); }
return result;
}

Download Excel File Via Servlet

I am using the below code invoked via ajax call for create my excel file.On click the download button excel file gets generate at the root location. But I am not able to see the prompt for user to save/save as the file. I can see the response tab of browser where the content of excel are coming. But I want that Save As dialog option to come. Any correction in below code that can solve this issue?
final Date date = new Date();
final String generateDate= new SimpleDateFormat("yyyy-MM-dd").format(date);
final String filename = form_name+"-extraction-"+generateDate.toString()+".xls";
final FileOutputStream fileOutputStream = new FileOutputStream(filename);
workbook.write(fileOutputStream);
downloadFile(filename, response);
Below is download file method :
private void downloadFile(final String fileName, final SlingHttpServletResponse response){
try {
final File f = new File(fileName);
response.setContentType("application/vnd.ms-excel");
response.setHeader("Content-Disposition", "inline; filename="+fileName);
response.setHeader("Pragma", "public");
response.setHeader("Cache-Control", "no-store");
response.addHeader("Cache-Control", "max-age=0");
FileInputStream fin = null;
try {
fin = new FileInputStream(f);
} catch (final FileNotFoundException e) {
e.printStackTrace();
}
final int size = 1024;
try {
response.setContentLength(fin.available());
final byte[] buffer = new byte[size];
ServletOutputStream os = null;
os = response.getOutputStream();
int length = 0;
while ((length = fin.read(buffer)) != -1) {
os.write(buffer, 0, length);
}
fin.close();
os.flush();
os.close();
} catch (final IOException e) {
e.printStackTrace();
}
}catch (final Exception ex){
LOGGER.error("ERROR IS ::: {}",ex.getMessage());
}

If the disposition type matches "attachment" (case-insensitively),
this indicates that the recipient should prompt the user to save the
response locally, rather than process it normally (as per its media
type).
On the other hand, if it matches "inline" (case-insensitively),
this implies default processing. Therefore, the disposition type
"inline" is only useful when it is augmented with additional
parameters, such as the filename (see below).
Unknown or unhandled disposition types SHOULD be handled by
recipients the same way as "attachment" (see also [RFC2183],
Section 2.8).
So you are forcing the browser to show the file instead of downloading it with your
response.setHeader("Content-Disposition", "inline; filename="+fileName);
call. You should use "attachment" instead of "inline".
response.setHeader("Content-Disposition", "attachment; filename="+fileName);
Read Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP) for more info.

If previous searched data output is populated in Excel, you should remove static declarations. For example:
private static hasmap hs = new hashmap();

Download a file through an HTTP Get in java

I've written a download Servlet to return a file based on a messageID parameter. Below is the doGet method.
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// This messageID would be used to get the correct file eventually
long messageID = Long.parseLong(request.getParameter("messageID"));
String fileName = "C:\\Users\\Soto\\Desktop\\new_audio1.amr";
File returnFile = new File(fileName);
ServletOutputStream out = response.getOutputStream();
ServletContext context = getServletConfig().getServletContext();
String mimetype = context.getMimeType("C:\\Users\\Soto\\Desktop\\new_audio1.amr");
response.setContentType((mimetype != null) ? mimetype : "application/octet-stream");
response.setContentLength((int)returnFile.length());
response.setHeader("Content-Disposition", "attachment; filename=\"" + "new_audio.amr" + "\"");
FileInputStream in = new FileInputStream(returnFile);
byte[] buffer = new byte[4096];
int length;
while((length = in.read(buffer)) > 0) {
out.write(buffer, 0, length);
}
in.close();
out.flush();
}
I then wrote some code to retrieve the file.
String url = "http://localhost:8080/AudioFileUpload/DownloadServlet";
String charset = "UTF-8";
// The id of the audio message requested
String messageID = "1";
//URLConnection connection = null;
try {
String query = String.format("messageID=%s", URLEncoder.encode(messageID, charset));
//URLConnection connection;
//URL u = new URL(url + "?" + query);
//connection = u.openConnection();
//InputStream in = connection.getInputStream();
HttpClient httpClient = new DefaultHttpClient();
httpClient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);
HttpGet httpGet = new HttpGet(url + "?" + query);
HttpResponse response = httpClient.execute(httpGet);
System.out.println(response.getStatusLine());
InputStream in = response.getEntity().getContent();
FileOutputStream fos = new FileOutputStream(new File("C:\\Users\\Soto\\Desktop\\new_audio2.amr"));
byte[] buffer = new byte[4096];
int length;
while((length = in.read(buffer)) > 0) {
fos.write(buffer, 0, length);
}
//connection = new URL(url + "?" + query).openConnection();
//connection.setRequestProperty("Accept-Charset", charset);
//InputStream response = connection.getInputStream();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Now this code works fine. I can download the audio file and it works correctly. What I want to know is how to, if possible, get the name of the file as it is downloaded instead of giving it my own name. Also, is it possible to get the file without having to read from the stream (maybe some library that does it for you)? I kind of want to hide the dirty stuff.
Thanks

For setting the download file name do the following on response object in Servlet code
response.setHeader("Content-disposition",
"attachment; filename=" +
"new_audio1.amr" );
EDIT:
I see you are already doing it. Just try removing the slashes you have added.

With attachment, the file will be served with the provided name properly. When inline, browsers seem to ignore filename, and usually give the servletname part of the URL as default name when saving the inline contents.
You could try mapping that URL to an appropriate filename, if that is suitable.
Here's a SO related question: Securly download file inside browser with correct filename
You may also find this link useful: Filename attribute for Inline Content-Disposition Meaningless?
I think you cannot download file without streaming. For I/O you must use stream.

Download process is not visible while servlet is downloading pdf

I m using content-disposition to download pdf . When I click the download button, the complete pdf file is downloaded first and then browser shows the dialog box to save the file. I want the browser to show the process of downloading. The following is my servlet code:
String filename = "abc.pdf";
String filepath = "/pdf/" + filename;
resp.setContentType("application/pdf");
resp.addHeader("content-disposition", "attachment; filename=" + filename);
ServletContext ctx = getServletContext();
InputStream is = ctx.getResourceAsStream(filepath);
System.out.println(is.toString());
int read = 0;
byte[] bytes = new byte[1024];
OutputStream os = resp.getOutputStream();
while ((read = is.read(bytes)) != -1) {
os.write(bytes, 0, read);
}
System.out.println(read);
os.flush();
os.close();
}catch(Exception ex){
logger.error("Exception occurred while downloading pdf -- "+ex.getMessage());
System.out.println(ex.getStackTrace());
}

The progress cannot be determined without knowing the response body's content length beforehand in the client side. To let the client know about the content length, you need to set the Content-Length header in the server side.
Change the line
InputStream is = ctx.getResourceAsStream(filepath);
to
URL resource = ctx.getResource(filepath);
URLConnection connection = resource.openConnection();
response.setContentLength(connection.getContentLength()); // <---
InputStream is = connection.getInputStream();
// ...
Unrelated to the concrete problem, your exception handling is bad. Replace the line
System.out.println(ex.getStackTrace());
by
throw new ServletException(ex);