// Socket Programming
// File download using Http Socket
import java.io.*;
import java.net.*;
public class Filedownload
{
private
final static int BUF_SIZE = 4096;
public
static void downloadFile(String fileURL, String targetDir) throws IOException
{
URL
url = new URL(fileURL);
//
Establish connection to remote URL
HttpURLConnection
conc = (HttpURLConnection) url.openConnection();
//
Check response code for connection status.
//
Use static variable (HttpURLConnection.HTTP_OK) or its code (200).
int
responseCode = conc.getResponseCode();
//
if (responseCode == HttpURLConnection.HTTP_OK)
if
(responseCode == 200)
{
//
Get information about the file and its content
String
fileName = "";
String
content = conc.getHeaderField("Content-Disposition");
String
contentType = conc.getContentType();
int
contentLength = conc.getContentLength();
if
(content != null)
{
//
Extract file name from header field
int
index = content.indexOf("filename=");
if
(index > 0)
{
fileName
= content.substring(index + 10,content.length() - 1);
}
}
else
{
//
Extract file name from URL
fileName
= fileURL.substring(fileURL.lastIndexOf("/") + 1, fileURL.length());
}
System.out.println("Content-Type =
" + contentType);
System.out.println("Content-Length =
" + contentLength);
System.out.println("fileName = "
+ fileName);
// Open input stream from the HTTP
connection
InputStream in = conc.getInputStream();
String filepath = targetDir +
File.separator + fileName;
// Open output stream to save content to
file
FileOutputStream out = new
FileOutputStream(filepath);
int data = -1;
byte[] buf = new byte[BUF_SIZE];
while
((data = in.read(buf)) != -1)
{
out.write(buf,
0, data);
}
out.close();
in.close();
System.out.println("File
downloaded");
}
else
{
System.out.println("No file to
download. ");
System.out.println("Server replied
HTTP code: " + responseCode);
}
conc.disconnect();
}
public static void main(String[] args)
{
String fileURL =
"http://drranurekha.com/wp-content/uploads/2018/02/3-Segmentation.pdf";
String targetDir =
"D:/cnlab/Http_socket";
try
{
downloadFile(fileURL,
targetDir);
}
catch (IOException E)
{
E.printStackTrace();
}
}
}
/*
Note 1: Specify the URL for file to
download clearly
Example:
Open
a pdf file in BROWSER.
Check
the address bar and copy the link in url=""
Paste
it in string fileURL
*/
/*
Note 2:
response code retrieves the status of the
http connection.
Example:
HTTP_OK
- HTTP Status-Code 200: OK.
HTTP_ACCEPTED
- HTTP Status-Code 202: Accepted.
HTTP_NO_CONTENT
- HTTP Status-Code 204: No Content.
HTTP_FORBIDDEN
- HTTP Status-Code 403: Forbidden.
HTTP_CLIENT_TIMEOUT
- HTTP Status-Code 408: Request Time-Out.
HTTP_BAD_GATEWAY
- HTTP Status-Code 502: Bad Gateway.
*/
/*
Note 3:
The MIME Content-disposition header
provides presentation information for the body-part. It is often added to
attachments specifying whether the attachment body part should be displayed
(inline) or presented as a file name to be copied (attachment)
*/
Sample Output:
> javac Filedownload.java
> java Filedownload
Content-Type = application/pdf
Content-Length = 211589
fileName = 3-Segmentation.pdf
File downloaded
>
