download file with http

[stemy]

Hi
I need to write a small client application in java that uses http in order to downlaod a file from the internet.
I suppose I should use

URLConnection.getInputStream[code] and send that stream as a constructor parameter for another cusom input stream, only I don't know which one to use. Am I getting this right? what should I do?
thanx.

 

[sedj]

This code will connect to a URL, and download ascii data. If you need to download byte[] data, then you need to change the input/output streams slightly, but this will give you an idea how to start with a simple ascii file.

	URL url = new URL("[URL unfurl="true"]http://www.acme.com/files/downloads/afile.html");[/URL]
	HttpURLConnection httpURL = (HttpURLConnection)url.openConnection();
	httpURL.setRequestMethod("GET");
	httpURL.setDoInput(true);
	httpURL.setDoOutput(true);
	httpURL.setUseCaches(false);

	// This commented block is used for writing parameters to the URL
	// EG - if used the final URL would look like [URL unfurl="true"]http://www.acme.com/files/downloads/afile.html?user=abc&area=something[/URL]
	//String params = "user=abc&area=something";
	//System.out.println(params);
	//byte[] data = params.getBytes();
	//DataOutputStream dos = new DataOutputStream(httpURL.getOutputStream() );
	//dos.write(data);
	//dos.close();

	BufferedReader br = new BufferedReader(new InputStreamReader(httpURL.getInputStream()));
	PrintWriter out = new PrintWriter(new OuputStreamWriter(new FileOutputStream("afile.html")));
	
	String line = "";
	while ((line = br.readLine()) != null) {
		out.println(line);
		System.out.println(line);
	}

 

[sedj]

PS, don't forget to flush and close your streams at the end -

out.flush();
out.close();
br.close();

 

[stemy]

thanx. but now, how do I upload a file ?

 

[stemy]

plus, I can't seen to make it work with binary files.

 

[sedj]

When you say "upload" - do you mean from a browser client to the server ? The code sample I posted will do it for ascii files, but as I said, requires some modification for binary files.

 

[stemy]

I need, from within an application that doesn't have to do with a browser, to specify a file and URL, and to upload that file.
I whould also appriciate help with those binary files.
thanks a lot.

 

[sedj]

I'm confused. Your title for this post says "download", but now you say "upload". Do you wish to transfer a file from a web server to an application, or from an application to a web server ?

 

[stemy]

I appologize. I need to do both.

 

[sedj]

The code I posted will get a file from a web server to the application. To used binary files, replace the BufferedReader object with a BufferedInStream, and the PrintWriter object with BufferedOutputStream, and then read the data an int at a time - this will succesfully download a binary file.

To upload a file from an application to a web server, the process is similar, but reversed, and you of course also need some code to read the file in at the web server end.

 

[stemy]

I tried to look it up but I got nothing. what exactly should I put on the server? should it be a jsp file? a class file? what code should I run on the sever?

 

[sedj]

For what - upload or download ?

 

[stemy]

upload.

 

[sedj]

Well, one way would be to have a Servlet that implements the doPost() (HTTP POST) method. You can attach the binary file to the request parameter, and then write that out to disk, or db or whatever.

A common way to do this with a browser is to use the <input type=&quot;file> tag, but I am not sure how to implement this using a now-browser call. You'll have to experiment !