I have a simple put and get working, but can't seem to find how to do a delete? For reference, the put code is:
BufferedInputStream inStream = null;
FileOutputStream outStream = null;
try {
final String ftpConnectInfo = "ftp://"+user+":"+pass+"#"+destHost+"/"+destFilename+";type=i";
LOGGER.info("Connection String: {}", ftpConnectInfo);
URL url = new URL(ftpConnectInfo);
URLConnection con = url.openConnection();
inStream = new BufferedInputStream(con.getInputStream());
outStream = new FileOutputStream(origFilename);
int i = 0;
byte[] bytesIn = new byte[1024];
while ((i = inStream.read(bytesIn)) >= 0) {
outStream.write(bytesIn, 0, i);
}
}
Is there some way to modify the URL to do a delete?
Based on this discussion on JavaRanch, I'm not sure you can do it by just modifying the URL. Is there any particular reason why you're not just using a library class like Apache commons FTPClient?
I would take a look at commons-net or commons-vfs for Java FTP, what you are doing here is opening an input stream on a file and reading it, while you want to send a command and get an acknowledgment.
I think the URLConnection is just supposed to allow you to read data.
It implements some commands of the FTP protocol to allow you to fetch files. But i don't think there is any way to sneakily encode a DELETE command in a URL to allow you to do what you want.
As other have said: you have to use a full featured FTP client.
Related
I have a problem with downloading a zip file from an url.
It works well with firefox but with my app I have a 404.
Here is my code
URL url = new URL(reportInfo.getURI().toString());
HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
// Check for errors
int responseCode = con.getResponseCode();
InputStream inputStream;
if (responseCode == HttpURLConnection.HTTP_OK) {
inputStream = con.getInputStream();
} else {
inputStream = con.getErrorStream();
}
OutputStream output = new FileOutputStream("test.zip");
// Process the response
BufferedReader reader;
String line = null;
reader = new BufferedReader(new InputStreamReader(inputStream));
while ((line = reader.readLine()) != null) {
output.write(line.getBytes());
}
output.close();
inputStream.close();
Any idea ?
In Java 7, the easiest way to save a URL to a file is:
try (InputStream stream = con.getInputStream()) {
Files.copy(stream, Paths.get("test.zip"));
}
As for why you're getting a 404 - that hard to tell. You should check the value of url, which as greedybuddha says, you should get via URI.getURL(). But it's also possible that the server is using a user agent check or something similar to determine whether or not to give you the resource. You could try with something like cURL to fetch in programmatic way but without having to write any code yourself.
However, there another problem looming. It's a zip file. That's binary data. But you're using InputStreamReader, which is designed for text content. Don't do that. You should never use a Reader for binary data. Just use the InputStream:
byte[] buffer = new byte[8 * 1024]; // Or whatever
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) > 0) {
output.write(buffer, 0, bytesRead);
}
Note that you should close the streams in finally blocks, or use the try-with-resources statement if you're using Java 7.
After almost 2 workdays of Googling and trying several different possibilities I found throughout the web, I'm asking this question here, hoping that I might finally get an answer.
First of all, here's what I want to do:
I'm developing a client and a server application with the purpose of exchanging a lot of large files between multiple clients on a single server. The client is developed in pure Java (JDK 1.6), while the web application is done in Grails (2.0.0).
As the purpose of the client is to allow users to exchange a lot of large files (usually about 2GB each), I have to implement it in a way, so that the uploads are resumable, i.e. the users are able to stop and resume uploads at any time.
Here's what I did so far:
I actually managed to do what I wanted to do and stream large files to the server while still being able to pause and resume uploads using raw sockets. I would send a regular request to the server (using Apache's HttpClient library) to get the server to send me a port that was free for me to use, then open a ServerSocket on the server and connect to that particular socket from the client.
Here's the problem with that:
Actually, there are at least two problems with that:
I open those ports myself, so I have to manage open and used ports myself. This is quite error-prone.
I actually circumvent Grails' ability to manage a huge amount of (concurrent) connections.
Finally, here's what I'm supposed to do now and the problem:
As the problems I mentioned above are unacceptable, I am now supposed to use Java's URLConnection/HttpURLConnection classes, while still sticking to Grails.
Connecting to the server and sending simple requests is no problem at all, everything worked fine. The problems started when I tried to use the streams (the connection's OutputStream in the client and the request's InputStream in the server). Opening the client's OutputStream and writing data to it is as easy as it gets. But reading from the request's InputStream seems impossible to me, as that stream is always empty, as it seems.
Example Code
Here's an example of the server side (Groovy controller):
def test() {
InputStream inStream = request.inputStream
if(inStream != null) {
int read = 0;
byte[] buffer = new byte[4096];
long total = 0;
println "Start reading"
while((read = inStream.read(buffer)) != -1) {
println "Read " + read + " bytes from input stream buffer" //<-- this is NEVER called
}
println "Reading finished"
println "Read a total of " + total + " bytes" // <-- 'total' will always be 0 (zero)
} else {
println "Input Stream is null" // <-- This is NEVER called
}
}
This is what I did on the client side (Java class):
public void connect() {
final URL url = new URL("myserveraddress");
final byte[] message = "someMessage".getBytes(); // Any byte[] - will be a file one day
HttpURLConnection connection = url.openConnection();
connection.setRequestMethod("GET"); // other methods - same result
// Write message
DataOutputStream out = new DataOutputStream(connection.getOutputStream());
out.writeBytes(message);
out.flush();
out.close();
// Actually connect
connection.connect(); // is this placed correctly?
// Get response
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line = null;
while((line = in.readLine()) != null) {
System.out.println(line); // Prints the whole server response as expected
}
in.close();
}
As I mentioned, the problem is that request.inputStream always yields an empty InputStream, so I am never able to read anything from it (of course). But as that is exactly what I'm trying to do (so I can stream the file to be uploaded to the server, read from the InputStream and save it to a file), this is rather disappointing.
I tried different HTTP methods, different data payloads, and also rearranged the code over and over again, but did not seem to be able to solve the problem.
What I hope to find
I hope to find a solution to my problem, of course. Anything is highly appreciated: hints, code snippets, library suggestions and so on. Maybe I'm even having it all wrong and need to go in a totally different direction.
So, how can I implement resumable file uploads for rather large (binary) files from a Java client to a Grails web application without manually opening ports on the server side?
HTTP GET method have special headers for range retrieval: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35 It's used by most downloaders to do resumable download from server.
As I understand, there are no standard practice for using this headers for POST/PUT request, but it's up to you, right? You can make pretty standard Grails controller, that will accept standard http upload, with header like Range: bytes=500-999. And controller should put this 500 uploaded bytes from client into file, starting at position 500
At this case you don't need to open any socket, and make own protocols, etc.
P.S. 500 bytes is just a example, probably you're using much bigger parts.
Client Side Java Programming:
public class NonFormFileUploader {
static final String UPLOAD_URL= "http://localhost:8080/v2/mobileApp/fileUploadForEOL";
static final int BUFFER_SIZE = 4096;
public static void main(String[] args) throws IOException {
// takes file path from first program's argument
String filePath = "G:/study/GettingStartedwithGrailsFinalInfoQ.pdf";
File uploadFile = new File(filePath);
System.out.println("File to upload: " + filePath);
// creates a HTTP connection
URL url = new URL(UPLOAD_URL);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
httpConn.setDoOutput(true);
httpConn.setRequestMethod("POST");
// sets file name as a HTTP header
httpConn.setRequestProperty("fileName", uploadFile.getName());
// opens output stream of the HTTP connection for writing data
OutputStream outputStream = httpConn.getOutputStream();
// Opens input stream of the file for reading data
FileInputStream inputStream = new FileInputStream(uploadFile);
byte[] buffer = new byte[BUFFER_SIZE];
int bytesRead = -1;
while ((bytesRead = inputStream.read(buffer)) != -1) {
System.out.println("bytesRead:"+bytesRead);
outputStream.write(buffer, 0, bytesRead);
outputStream.flush();
}
System.out.println("Data was written.");
outputStream.flush();
outputStream.close();
inputStream.close();
int responseCode = httpConn.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
// reads server's response
BufferedReader reader = new BufferedReader(new InputStreamReader(
httpConn.getInputStream()));
String response = reader.readLine();
System.out.println("Server's response: " + response);
} else {
System.out.println("Server returned non-OK code: " + responseCode);
}
}
}
Server Side Grails Programme:
Inside the controller:
def fileUploadForEOL(){
def result
try{
result = mobileAppService.fileUploadForEOL(request);
}catch(Exception e){
log.error "Exception in fileUploadForEOL service",e
}
render result as JSON
}
Inside the Service Class:
def fileUploadForEOL(request){
def status = false;
int code = 500
def map = [:]
try{
String fileName = request.getHeader("fileName");
File saveFile = new File(SAVE_DIR + fileName);
System.out.println("===== Begin headers =====");
Enumeration<String> names = request.getHeaderNames();
while (names.hasMoreElements()) {
String headerName = names.nextElement();
System.out.println(headerName + " = " + request.getHeader(headerName));
}
System.out.println("===== End headers =====\n");
// opens input stream of the request for reading data
InputStream inputStream = request.getInputStream();
// opens an output stream for writing file
FileOutputStream outputStream = new FileOutputStream(saveFile);
byte[] buffer = new byte[BUFFER_SIZE];
int bytesRead = inputStream.read(buffer);
long count = bytesRead
while(bytesRead != -1) {
outputStream.write(buffer, 0, bytesRead);
bytesRead = inputStream.read(buffer);
count += bytesRead
}
println "count:"+count
System.out.println("Data received.");
outputStream.close();
inputStream.close();
System.out.println("File written to: " + saveFile.getAbsolutePath());
code = 200
}catch(Exception e){
mLogger.log(java.util.logging.Level.SEVERE,"Exception in fileUploadForEOL",e);
}finally{
map <<["code":code]
}
return map
}
I have tried with above code it is worked for me(only for file size 3 to 4MB, but for small size files some bytes of code missing or not even coming but in request header content-length is coming, not sure why it is happening.)
I have a requirement, where i need to process a set of files and create a compressed zip file out of it and then use it for download. I am using a Servlet for downloading that file, but the download takes quite sometime. So i want the user to know that the servlet is processing the request through a print writer output messsage instead of showing him a blank screen.But everytime i use a printwriter to write something to the screen, the message takes a lot of time to show on the screen and the file doesnt download.
How can i achieve this? Any ides?
Thanks.
Here's my code
OutputStream oStream = null;
DataInputStream dInput = null;
File file = new File(("PATH"));
int length = 0;
try{
DownloadServerLogs.processLogs();
oStream = res.getOutputStream();
res.setContentType("application/zip");
res.setContentLength((int)file.length());
res.setHeader("Content-Disposition",
"attachment;filename=\"" + file.getName() + "\"" );
byte[] bbuf = new byte[BYTES_DOWNLOAD];
dInput = new DataInputStream(new FileInputStream(file));
while ((dInput != null) && ((length = dInput.read(bbuf)) != -1))
{
oStream.write(bbuf,0,length);
}
dInput.close();
oStream.flush();
oStream.close();
}catch(Exception e){
Utility.getLogger().error(e.getMessage(), e);
}
I guess its better to display the message to the client by using something like Javascript (assuming you are using AJAX to invoke the servlet).
Well, it's probably not that safe to do it that way. I'd have a look at the answer below. Not that it's your exact problem, but might be similar.
Most efficient way to create InputStream from OutputStream
Effectively, you are reading and writing on the same thread and my guess is that with the addition of the PrintWriter you are getting deadlocked somewhere.
In my Java swing program, I read, edit and save various text files in a local folder using Scanner and BufferedWriter. Is there an easy way I can keep my current code, but, using FTP, edit a web file rather than a local file? Thanks everyone.
You can use the URL and URLConnection classes to obtain InputStreams and OutputStreams to files located on an FTP Server.
To read a file
URL url = new URL("ftp://user:pass#my.ftphost.com/myfile.txt");
InputStream in = url.openStream();
to write a file
URL url = new URL("ftp://user:pass#my.ftphost.com/myfile.txt");
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStream out = conn.getOutputStream();
I tried to achieve the same and the answers to those questions helped me a lot:
Adding characters to beginning and end of InputStream in Java (the one marked as right shows how to add a custom string to the InputStream)
Uploading a file to a FTP server from android phone? (the one from Kumar Vivek Mitra shows how to upload a file)
I added new text to the end of my online file like this:
FTPClient con = null;
try {
con = new FTPClient();
con.connect(Hostname);
if (con.login(FTPUsername, FTPPassword)) {
con.enterLocalPassiveMode(); // important!
con.setFileType(FTP.BINARY_FILE_TYPE);
InputStream onlineDataIS = urlOfOnlineFile.openStream();
String end = "\nteeeeeeeeeeeeeeeeest";
List<InputStream> streams = Arrays.asList(
onlineDataIS,
new ByteArrayInputStream(end.getBytes()));
InputStream resultIS = new SequenceInputStream(Collections.enumeration(streams));
// Stores a file on the server using the given name and taking input from the given InputStream.
boolean result = con.storeFile(PathOfTargetFile, resultIS);
onlineDataIS.close();
resultIS.close();
if (result) Log.v("upload result", "succeeded");
con.logout();
con.disconnect();
}
return "Writing successful";
} catch (IOException e) {
// some smart error handling
}
Hope that helps.
I would like to upload files from java application/applet using POST http event. I would like to avoid to use any library not included in SE, unless there is no other (feasible) option.
So far I come up only with very simple solution.
- Create String (Buffer) and fill it with compatible header (http://www.ietf.org/rfc/rfc1867.txt)
- Open connection to server URL.openConnection() and write content of this file to OutputStream.
I also need to manually convert binary file into POST event.
I hope there is some better, simpler way to do this?
You need to use the java.net.URL and java.net.URLConnection classes.
There are some good examples at http://java.sun.com/docs/books/tutorial/networking/urls/readingWriting.html
Here's some quick and nasty code:
public void post(String url) throws Exception {
URL u = new URL(url);
URLConnection c = u.openConnection();
c.setDoOutput(true);
if (c instanceof HttpURLConnection) {
((HttpURLConnection)c).setRequestMethod("POST");
}
OutputStreamWriter out = new OutputStreamWriter(
c.getOutputStream());
// output your data here
out.close();
BufferedReader in = new BufferedReader(
new InputStreamReader(
c.getInputStream()));
String s = null;
while ((s = in.readLine()) != null) {
System.out.println(s);
}
in.close();
}
Note that you may still need to urlencode() your POST data before writing it to the connection.
You need to learn about the chunked encoding used in newer versions of HTTP. The Apache HttpClient library is a good reference implementation to learn from.