I have got this piece of code (I didn't write, just maintaining):
public class MyMultipartResolver extends CommonsMultipartResolver{
public List parseEmptyRequest(HttpServletRequest request) throws IOException, FileUploadException {
String contentType = request.getHeader(CONTENT_TYPE);
int boundaryIndex = contentType.indexOf("boundary=");
InputStream input = request.getInputStream();
byte[] boundary = contentType.substring(boundaryIndex + 9).getBytes();
MultipartStream multi = new MultipartStream(input, boundary);
multi.setHeaderEncoding(getHeaderEncoding());
ArrayList items = new ArrayList();
boolean nextPart = multi.skipPreamble();
while (nextPart) {
Map headers = parseHeaders(multi.readHeaders());
// String fieldName = getFieldName(headers);
String subContentType = getHeader(headers, CONTENT_TYPE);
if (subContentType == null) {
FileItem item = createItem(headers, true);
OutputStream os = item.getOutputStream();
try {
multi.readBodyData(os);
} finally {
os.close();
}
items.add(item);
} else {
multi.discardBodyData();
}
nextPart = multi.readBoundary();
}
return items;
}
}
I am using commons-fileupload.jar version 1.2.1 and obviously the code is using some deprecated methods...
Anyway, while trying to use this code to upload a very large file (780 MB) I get this:
org.apache.commons.fileupload.MultipartStream$MalformedStreamException: Stream ended unexpectedly
at org.apache.commons.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:983)
at org.apache.commons.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:887)
at java.io.InputStream.read(InputStream.java:89)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:94)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:64)
at org.apache.commons.fileupload.MultipartStream.readBodyData(MultipartStream.java:593)
at org.apache.commons.fileupload.MultipartStream.discardBodyData(MultipartStream.java:619)
that is thrown from 'multi.discardBodyData();' line.
My question:
How can I avoid this error and be able to be able to succeed collecting the FileItems?
catch
(org.apache.commons.fileupload.MultipartStream.MalformedStreamException e)
{
e.printStackTrace();
return ERROR;
}
Catch the exception and handle it via ..either InputStream or Return Error use it in struts action tag
Related
Basically I have this method that I got off a tutorial (My main goal is to simply return the images from the spring boot server so that I could dynamically view them in Angular)
#RestController
public class FileController {
#Autowired
ServletContext context;
#GetMapping(path = "/allImages")
public ResponseEntity<List<String>> getImages(){
List<String> images = new ArrayList<String>();
String filesPath = context.getRealPath("/images");
File fileFolder = new File(filesPath);
if(fileFolder!=null) {
for(final File file : fileFolder.listFiles()) {
if(!file.isDirectory()) {
String encodeBase64 = null;
try {
String extention = FilenameUtils.getExtension(file.getName());
FileInputStream fileInputStream = new FileInputStream(file);
byte[] bytes = new byte[(int)file.length()];
encodeBase64 = Base64.getEncoder().encodeToString(bytes);
images.add("data:image/"+extention+";base64,"+encodeBase64);
fileInputStream.close();
} catch (Exception e) {
// TODO: handle exception
}
}
}
}
return new ResponseEntity<List<String>>(HttpStatus.OK);
}
With the current code, when I try to return the files, I get:
java.lang.NullPointerException: Cannot read the array length because the return value of "java.io.File.listFiles()" is null
I've been searching around and noticed that people recommend using java.nio.file instead but I'm a little lost on how would I implement this here. Any help is appreciated.
Example with nio:
public List<String> readImages() throws IOException {
return Files.list(Path.of("/images"))
.filter(Files::isRegularFile)
.map(this::encode)
.filter(Objects::nonNull)
.collect(Collectors.toList());
}
private String encode(Path file) {
try {
String extension = FilenameUtils.getExtension(file.getFileName().toString());
String encodeBase64 = Base64.getEncoder().encodeToString(Files.readAllBytes(file));
return "data:image/"+extension+";base64,"+encodeBase64;
} catch (Exception e) {
return null;
}
}
First get a Path to your folder:
Path folderPath = Paths.get(filesPath);
If your Path points to a directory, you can get a Stream<Path> of its contents using Files.list:
if (Files.isDirectory(folderPath)) {
List<Path> files = Files.list(folderPath)
.filter(path -> !Files.isDirectory(path))
.collect(Collectors.toList());
// Do something with the files.
}
It doesn't look like you are using the FileInputStream for anything, so you shouldn't need to translate that part. To get the file extension of your path, you probably need to convert the Path to a string, and extract the extension yourself.
I solved this issue with this code:
#Autowired
ServletContext context;
#GetMapping(path = "/allImages")
public List<String> readImages() throws IOException {
return Files.list(Paths.get(context.getRealPath("/images")))
.filter(Files::isRegularFile)
.map(this::encode)
.filter(Objects::nonNull)
.collect(Collectors.toList());
}
private String encode(Path file) {
try {
String extension = FilenameUtils.getExtension(file.getFileName().toString());
String encodeBase64 = Base64.getEncoder().encodeToString(Files.readAllBytes(file));
return "data:image/"+extension+";base64,"+encodeBase64;
} catch (Exception e) {
return null;
}
}
Thank you to everyone who helped.
I have A big file and i want to upload that in Server side. it's very important when occured any problem (like interrupting the internet or power cut ...) if i retry to upload, file uploaded from resume and doesn't need to send file from beginning.
I try this approach with sending file chunks but it seems that's not a good way, because a send chunks(byte arrays) directly in response Entity and this isn't good idea.
whatever if anybody can develop this approach and make this code a better code with better performance i appreciate that. does anybody known Best practice way to doing that??
and if u like my code, vote me
thanks :)
RestController
#RestController
#RequestMapping("/files")
public class Controller {
#Autowired
private MyService service;
#PutMapping("/upload/resume")
public Mono<ResponseEntity> uploadWithResume(#RequestPart("chunk")byte[] chunk,
#RequestPart("fileName")String fileName,
#RequestParam("length")Long length
) throws ParseException {
try {
return service.fileResumeUpload(chunk, fileName, length);
} catch (IOException e) {
e.printStackTrace();
return Mono.just(ResponseEntity.status(HttpStatus.PERMANENT_REDIRECT).build());
}
}
#RequestMapping(value = "/get/uploaded/size", method = RequestMethod.HEAD)
public Mono<ResponseEntity> getUploadedSize(#RequestParam("fileName") String fileName) throws IOException {
if (Files.exists(Paths.get("src/main/resources/" + fileName))) {
String size = String.valueOf(Files.size(Paths.get("src/main/resources/" + fileName)));
return Mono.just(ResponseEntity.ok()
.header("upload-offset", size)
.build());
} else{
return Mono.just(ResponseEntity.notFound()
.header("upload-offset" , "0").build());
}
}
}
Service
public Mono<ResponseEntity> fileResumeUpload(byte[] chunk , String fileName,long length) throws IOException, ParseException {
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream("src/main/resources/" + fileName, true));
boolean uploaded = true;
try {
out.write(chunk);
} catch (IOException e) {
uploaded = false;
System.err.println("io exception");
} finally {
if (uploaded) {
out.close();
return Mono.just(ResponseEntity.ok()
.header("expiration-date", getExpirationDate())
.build());
} else {
out.close();
return Mono.just(ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build());
}
}
}
Sending chunks with webTestClient
#Test
public void test1_upload_Expected_200StatusCode(){
try {
String fileName = "film.mkv";
RandomAccessFile raf = new RandomAccessFile(new File("src/test/resources/" + fileName), "rw");
long realSize = raf.length();
List<String> strings = webTestClient.head().uri("/files/get/uploaded/size?fileName=" + fileName)
.exchange().expectBody().returnResult().getResponseHeaders().get("upload-offset");
long uploadedSize = Long.valueOf(strings.get(0));
boolean f = false;
int sizeBuffer = 256 * 1024;
byte[] buffer = new byte[sizeBuffer];
MultiValueMap<String, Object> formData;
WebTestClient.ResponseSpec exchange = null;
System.out.println("first uploaded Size ; " + uploadedSize);
raf.seek(uploadedSize);
while (raf.read(buffer) != -1) {
formData = new LinkedMultiValueMap<>();
formData.add("fileName", fileName);
formData.add("chunk", buffer);
formData.add("length", realSize);
exchange = webTestClient.put().uri("/files/upload/resume")
.contentType(MediaType.MULTIPART_FORM_DATA)
.body(BodyInserters.fromMultipartData(formData))
.exchange();
exchange.expectStatus().isOk();
if (exchange.expectBody().returnResult().getStatus().is5xxServerError()) {
return;
}
if (uploadedSize + 256 * 1024 > realSize) {
sizeBuffer = ((int) (realSize - uploadedSize));
System.out.println(sizeBuffer);
uploadedSize = uploadedSize + sizeBuffer;
System.out.println(uploadedSize);
buffer = new byte[sizeBuffer];
f=true;
} else uploadedSize = uploadedSize + sizeBuffer;
if (f) System.out.println(uploadedSize);
//System.out.println(uploadedSize);
float percent = ((float) uploadedSize / realSize * 100);
System.out.format("%.2f\n", percent);
}
if (exchange!=null)
exchange.expectStatus().isOk();
}
catch (Exception e){
e.printStackTrace();
System.err.println("channel closed!!!");
}
}
Does anyone know where to find a little how to on using dbpedia spotlight in java or scala? Or could anyone explain how it's done? I can't find any information on this...
The DBpedia Spotlight wiki pages would be a good place to start.
And I believe the installation page has listed the most popular ways (using a jar, or set up a web service) to use the application.
It includes instructions on using the Java/Scala API with your own installation, or calling the Web Service.
There are some additional data needed to be downloaded to run your own server for full service, good time to make a coffee for yourself.
you need download dbpedia spotlight (jar file) after that u can use next two classes ( author pablomendes ) i only make some change .
public class db extends AnnotationClient {
//private final static String API_URL = "http://jodaiber.dyndns.org:2222/";
private static String API_URL = "http://spotlight.dbpedia.org:80/";
private static double CONFIDENCE = 0.0;
private static int SUPPORT = 0;
private static String powered_by ="non";
private static String spotter ="CoOccurrenceBasedSelector";//"LingPipeSpotter"=Annotate all spots
//AtLeastOneNounSelector"=No verbs and adjs.
//"CoOccurrenceBasedSelector" =No 'common words'
//"NESpotter"=Only Per.,Org.,Loc.
private static String disambiguator ="Default";//Default ;Occurrences=Occurrence-centric;Document=Document-centric
private static String showScores ="yes";
#SuppressWarnings("static-access")
public void configiration(double CONFIDENCE,int SUPPORT,
String powered_by,String spotter,String disambiguator,String showScores){
this.CONFIDENCE=CONFIDENCE;
this.SUPPORT=SUPPORT;
this.powered_by=powered_by;
this.spotter=spotter;
this.disambiguator=disambiguator;
this.showScores=showScores;
}
public List<DBpediaResource> extract(Text text) throws AnnotationException {
LOG.info("Querying API.");
String spotlightResponse;
try {
String Query=API_URL + "rest/annotate/?" +
"confidence=" + CONFIDENCE
+ "&support=" + SUPPORT
+ "&spotter=" + spotter
+ "&disambiguator=" + disambiguator
+ "&showScores=" + showScores
+ "&powered_by=" + powered_by
+ "&text=" + URLEncoder.encode(text.text(), "utf-8");
LOG.info(Query);
GetMethod getMethod = new GetMethod(Query);
getMethod.addRequestHeader(new Header("Accept", "application/json"));
spotlightResponse = request(getMethod);
} catch (UnsupportedEncodingException e) {
throw new AnnotationException("Could not encode text.", e);
}
assert spotlightResponse != null;
JSONObject resultJSON = null;
JSONArray entities = null;
try {
resultJSON = new JSONObject(spotlightResponse);
entities = resultJSON.getJSONArray("Resources");
} catch (JSONException e) {
//throw new AnnotationException("Received invalid response from DBpedia Spotlight API.");
}
LinkedList<DBpediaResource> resources = new LinkedList<DBpediaResource>();
if(entities!=null)
for(int i = 0; i < entities.length(); i++) {
try {
JSONObject entity = entities.getJSONObject(i);
resources.add(
new DBpediaResource(entity.getString("#URI"),
Integer.parseInt(entity.getString("#support"))));
} catch (JSONException e) {
LOG.error("JSON exception "+e);
}
}
return resources;
}
}
second class
/**
* #author pablomendes
*/
public abstract class AnnotationClient {
public Logger LOG = Logger.getLogger(this.getClass());
private List<String> RES = new ArrayList<String>();
// Create an instance of HttpClient.
private static HttpClient client = new HttpClient();
public List<String> getResu(){
return RES;
}
public String request(HttpMethod method) throws AnnotationException {
String response = null;
// Provide custom retry handler is necessary
method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler(3, false));
try {
// Execute the method.
int statusCode = client.executeMethod(method);
if (statusCode != HttpStatus.SC_OK) {
LOG.error("Method failed: " + method.getStatusLine());
}
// Read the response body.
byte[] responseBody = method.getResponseBody(); //TODO Going to buffer response body of large or unknown size. Using getResponseBodyAsStream instead is recommended.
// Deal with the response.
// Use caution: ensure correct character encoding and is not binary data
response = new String(responseBody);
} catch (HttpException e) {
LOG.error("Fatal protocol violation: " + e.getMessage());
throw new AnnotationException("Protocol error executing HTTP request.",e);
} catch (IOException e) {
LOG.error("Fatal transport error: " + e.getMessage());
LOG.error(method.getQueryString());
throw new AnnotationException("Transport error executing HTTP request.",e);
} finally {
// Release the connection.
method.releaseConnection();
}
return response;
}
protected static String readFileAsString(String filePath) throws java.io.IOException{
return readFileAsString(new File(filePath));
}
protected static String readFileAsString(File file) throws IOException {
byte[] buffer = new byte[(int) file.length()];
#SuppressWarnings("resource")
BufferedInputStream f = new BufferedInputStream(new FileInputStream(file));
f.read(buffer);
return new String(buffer);
}
static abstract class LineParser {
public abstract String parse(String s) throws ParseException;
static class ManualDatasetLineParser extends LineParser {
public String parse(String s) throws ParseException {
return s.trim();
}
}
static class OccTSVLineParser extends LineParser {
public String parse(String s) throws ParseException {
String result = s;
try {
result = s.trim().split("\t")[3];
} catch (ArrayIndexOutOfBoundsException e) {
throw new ParseException(e.getMessage(), 3);
}
return result;
}
}
}
public void saveExtractedEntitiesSet(String Question, LineParser parser, int restartFrom) throws Exception {
String text = Question;
int i=0;
//int correct =0 ; int error = 0;int sum = 0;
for (String snippet: text.split("\n")) {
String s = parser.parse(snippet);
if (s!= null && !s.equals("")) {
i++;
if (i<restartFrom) continue;
List<DBpediaResource> entities = new ArrayList<DBpediaResource>();
try {
entities = extract(new Text(snippet.replaceAll("\\s+"," ")));
System.out.println(entities.get(0).getFullUri());
} catch (AnnotationException e) {
// error++;
LOG.error(e);
e.printStackTrace();
}
for (DBpediaResource e: entities) {
RES.add(e.uri());
}
}
}
}
public abstract List<DBpediaResource> extract(Text text) throws AnnotationException;
public void evaluate(String Question) throws Exception {
evaluateManual(Question,0);
}
public void evaluateManual(String Question, int restartFrom) throws Exception {
saveExtractedEntitiesSet(Question,new LineParser.ManualDatasetLineParser(), restartFrom);
}
}
main()
public static void main(String[] args) throws Exception {
String Question ="Is the Amazon river longer than the Nile River?";
db c = new db ();
c.configiration(0.0, 0, "non", "CoOccurrenceBasedSelector", "Default", "yes");
System.out.println("resource : "+c.getResu());
}
I just add one little fix for your answer.
Your code is running, if you add the evaluate method call:
public static void main(String[] args) throws Exception {
String question = "Is the Amazon river longer than the Nile River?";
db c = new db ();
c.configiration(0.0, 0, "non", "CoOccurrenceBasedSelector", "Default", "yes");
c.evaluate(question);
System.out.println("resource : "+c.getResu());
}
Lamine
In the request method of the second class (AnnotationClient) in Adel's answer, the author Pablo Mendes hasn't finished
TODO Going to buffer response body of large or unknown size. Using getResponseBodyAsStream instead is recommended.
which is an annoying warning that needs to be removed by replacing
byte[] responseBody = method.getResponseBody(); //TODO Going to buffer response body of large or unknown size. Using getResponseBodyAsStream instead is recommended.
// Deal with the response.
// Use caution: ensure correct character encoding and is not binary data
response = new String(responseBody);
with
Reader in = new InputStreamReader(method.getResponseBodyAsStream(), "UTF-8");
StringWriter writer = new StringWriter();
org.apache.commons.io.IOUtils.copy(in, writer);
response = writer.toString();
I've written a transformer class that takes an HttpServletRequest and transforms it into another type that holds a pointer to the InputStream from the servlet request. (The idea is to abstract the incoming transport protocol from the request handling, so I could also write a similar transformer from FTP, for instance.)
Now I'm trying to write a unit test for this, and I'm having problems. I've managed to figure out the correct boilerplate to create a valid Multipart HTTP request (using the Spring classes MockMultipartHttpServletRequest and MockMultipartFile), but now I get a NullPointerException in the initialize() method of my UploadRequest class. I'm guessing the problem is that somehow the stream inside the MockMultipartHttpServletRequest isn't being initialized correctly, but I can't figure out what I should do differently.
Any suggestions would be gratefully accepted!
This is the stack trace:
java.lang.NullPointerException
at org.apache.commons.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:976)
at org.apache.commons.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:886)
at java.io.InputStream.read(InputStream.java:82)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:96)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:66)
at org.apache.commons.fileupload.MultipartStream.readBodyData(MultipartStream.java:592)
at org.apache.commons.fileupload.MultipartStream.discardBodyData(MultipartStream.java:618)
at org.apache.commons.fileupload.MultipartStream.skipPreamble(MultipartStream.java:637)
at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.findNextItem(FileUploadBase.java:984)
at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:965)
at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:331)
at org.apache.commons.fileupload.servlet.ServletFileUpload.getItemIterator(ServletFileUpload.java:148)
at com.ooyala.UploadRequest.initialize(UploadRequest.java:51)
at com.ooyala.UploadRequestTest.testCreateFromServletRequest(UploadRequestTest.java:57)
Here's an abbreviated version of my transformer class:
public class UploadRequest {
private Map<String, String> params;
private InputStream strIn;
private Logger Log = Logger.getLogger(UploadRequest.class.getName());
public UploadRequest()
{
params = new HashMap<String, String>();
}
public void initialize(HttpServletRequest sRequest,
ServletFileUpload upload)
throws IOException, FileUploadException
{
Enumeration<String> paramNames = sRequest.getParameterNames();
while (paramNames.hasMoreElements()) {
String pName = paramNames.nextElement();
params.put(pName, sRequest.getParameter(pName));
}
params.put("request_uri", sRequest.getRequestURI());
FileItemIterator iter = upload.getItemIterator(sRequest);
while (iter.hasNext()) {
FileItemStream item = iter.next();
try {
if (!item.isFormField()) {
// Skip form fields
params.put("original_file_name", item.getName());
strIn = item.openStream();
}
} catch (IOException ex) {
Log.severe("File uploading exception: " + ex.getMessage());
throw ex;
}
}
}
And here's the unit test:
import org.springframework.mock.web.MockMultipartHttpServletRequest;
import org.springframework.mock.web.MockMultipartFile;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
// etc.... other imports
#RunWith(JMock.class)
public class UploadRequestTest {
private UploadRequest upRequest;
#Before
public void setUp()
{
context.setImposteriser(ClassImposteriser.INSTANCE);
upRequest = new UploadRequest();
}
#Test
public void testCreateFromServletRequest()
throws IOException, FileUploadException
{
String text_contents = "hello world";
MockMultipartHttpServletRequest sRequest =
new MockMultipartHttpServletRequest();
sRequest.setMethod("POST");
String boundary = generateBoundary();
String contentType = "multipart/form-data; boundary="+boundary;
sRequest.setContentType(contentType);
sRequest.setRequestURI("/foo");
sRequest.addParameter("test_param","test_value");
sRequest.addFile(
new MockMultipartFile("file1","test_upload.txt","text/plain",
text_contents.getBytes()));
ServletFileUpload upload = new ServletFileUpload();
assertTrue(upload.isMultipartContent(sRequest));
upRequest.initialize(sRequest, upload);
}
}
I have the same issue and I googled but no answer. I plugged in the source code from the library, You need to send content, whatever. The library might need to check if it is null in the skip method
MockMultipartHttpServletRequest request
request.setContent("whatever".getBytes());
Posted here for others
Add boundary condition
Generate contents as follows
MockMultipartHttpServletRequest request =
this.generateMockMultiPartHttpServletRequest(true);
MockMultipartFile mockMultipartFile = null;
try {
request.setContentType("multipart/form-data; boundary=-----1234");
request.setCharacterEncoding("text/plain");
String endline = "\r\n";
String bondary = "-----1234";
String textFile = this.encodeTextFile("-----1234", "\r\n", "file","test.csv",
"text/UTF-8", FileUtils.readFileToString((new File(csvFilePath)), "UTF-8"));
StringBuilder content = new StringBuilder(textFile.toString());
content.append(endline);
content.append(endline);
content.append(endline);
content.append("--");
content.append(bondary);
content.append("--");
content.append(endline);
request.setContent(content.toString().getBytes());
request.setMethod("POST");
mockMultipartFile = new MockMultipartFile("file",
FileUtils.readFileToByteArray(new File(csvFilePath)));
} catch (Exception e1) {
e1.printStackTrace();
}
request.addFile(mockMultipartFile);
Function to encode text
private String encodeTextFile(String bondary, String endline, String name,
String filename, String contentType, String content) {
final StringBuilder sb = new StringBuilder(64);
sb.append(endline);
sb.append("--");
sb.append(bondary);
sb.append(endline);
sb.append("Content-Disposition: form-data; name=\"");
sb.append(name);
sb.append("\"; filename=\"");
sb.append(filename);
sb.append("\"");
sb.append(endline);
sb.append("Content-Type: ");
sb.append(contentType);
sb.append(endline);
sb.append(endline);
sb.append(content);
return sb.toString();
}
I went through the same problem, after searching lot I got this post in which I answered with code that solved my problem.
The Shriprasad's solution works well for text file. But I had some problems with binary files.
https://stackoverflow.com/a/30541653/2762092
How can I use the library to download a file and print out bytes saved? I tried using
import static org.apache.commons.io.FileUtils.copyURLToFile;
public static void Download() {
URL dl = null;
File fl = null;
try {
fl = new File(System.getProperty("user.home").replace("\\", "/") + "/Desktop/Screenshots.zip");
dl = new URL("http://ds-forums.com/kyle-tests/uploads/Screenshots.zip");
copyURLToFile(dl, fl);
} catch (Exception e) {
System.out.println(e);
}
}
but I cannot display bytes or a progress bar. Which method should I use?
public class download {
public static void Download() {
URL dl = null;
File fl = null;
String x = null;
try {
fl = new File(System.getProperty("user.home").replace("\\", "/") + "/Desktop/Screenshots.zip");
dl = new URL("http://ds-forums.com/kyle-tests/uploads/Screenshots.zip");
OutputStream os = new FileOutputStream(fl);
InputStream is = dl.openStream();
CountingOutputStream count = new CountingOutputStream(os);
dl.openConnection().getHeaderField("Content-Length");
IOUtils.copy(is, os);//begin transfer
os.close();//close streams
is.close();//^
} catch (Exception e) {
System.out.println(e);
}
}
If you are looking for a way to get the total number of bytes before downloading, you can obtain this value from the Content-Length header in http response.
If you just want the final number of bytes after the download, it is easiest to check the file size you just write to.
However if you want to display the current progress of how many bytes have been downloaded, you might want to extend apache CountingOutputStream to wrap the FileOutputStream so that everytime the write methods are called it counts the number of bytes passing through and update the progress bar.
Update
Here is a simple implementation of DownloadCountingOutputStream. I am not sure if you are familiar with using ActionListener or not but it is a useful class for implementing GUI.
public class DownloadCountingOutputStream extends CountingOutputStream {
private ActionListener listener = null;
public DownloadCountingOutputStream(OutputStream out) {
super(out);
}
public void setListener(ActionListener listener) {
this.listener = listener;
}
#Override
protected void afterWrite(int n) throws IOException {
super.afterWrite(n);
if (listener != null) {
listener.actionPerformed(new ActionEvent(this, 0, null));
}
}
}
This is the usage sample :
public class Downloader {
private static class ProgressListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
// e.getSource() gives you the object of DownloadCountingOutputStream
// because you set it in the overriden method, afterWrite().
System.out.println("Downloaded bytes : " + ((DownloadCountingOutputStream) e.getSource()).getByteCount());
}
}
public static void main(String[] args) {
URL dl = null;
File fl = null;
String x = null;
OutputStream os = null;
InputStream is = null;
ProgressListener progressListener = new ProgressListener();
try {
fl = new File(System.getProperty("user.home").replace("\\", "/") + "/Desktop/Screenshots.zip");
dl = new URL("http://ds-forums.com/kyle-tests/uploads/Screenshots.zip");
os = new FileOutputStream(fl);
is = dl.openStream();
DownloadCountingOutputStream dcount = new DownloadCountingOutputStream(os);
dcount.setListener(progressListener);
// this line give you the total length of source stream as a String.
// you may want to convert to integer and store this value to
// calculate percentage of the progression.
dl.openConnection().getHeaderField("Content-Length");
// begin transfer by writing to dcount, not os.
IOUtils.copy(is, dcount);
} catch (Exception e) {
System.out.println(e);
} finally {
IOUtils.closeQuietly(os);
IOUtils.closeQuietly(is);
}
}
}
commons-io has IOUtils.copy(inputStream, outputStream). So:
OutputStream os = new FileOutputStream(fl);
InputStream is = dl.openStream();
IOUtils.copy(is, os);
And IOUtils.toByteArray(is) can be used to get the bytes.
Getting the total number of bytes is a different story. Streams don't give you any total - they can only give you what is currently available in the stream. But since it's a stream, it can have more coming.
That's why http has its special way of specifying the total number of bytes. It is in the response header Content-Length. So you'd have to call url.openConnection() and then call getHeaderField("Content-Length") on the URLConnection object. It will return the number of bytes as string. Then use Integer.parseInt(bytesString) and you'll get your total.