Upload a file to another webpage through a Java Servlet

Posted Sun, 11/01/2009 - 12:03 by manjula

In past few days, I had to work on implementing a functionality for sending an HTTP request to another url and upload a file with that HTTP request and then get the response for the HTTP request from a Java servlet. This is the code I finally created for achieving my task. It does,

1. Connect to another given URL
2. Upload given string as a file to the above url
3. Then read the response for the above HTTP request.

Below function is called inside the protected void processRequest(HttpServletRequest request, HttpServletResponse response) of a Servlet in my project. I have put the relevant code for achieving this task in below.

// Import these packages

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

// Code

private String uploadFile(String urlstring, String dataXML) {

try {

String itemname = "formFile";
String tempfilename = "test.xml";
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "---------------------------24464570528145";

URL url = new URL(urlstring);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();

connection.setDoOutput(true);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.setRequestMethod("POST");
connection.setRequestProperty("Connection", "keep-alive"); connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
connection.setRequestProperty("Accept-Charset", "ISO-8859-1,utf-8;q=0.7,*;q=0.7");
DataOutputStream dataoutputstream = new DataOutputStream(connection.getOutputStream());
dataoutputstream.writeBytes(twoHyphens + boundary + lineEnd);
dataoutputstream.writeBytes("Content-Disposition: form-data; name=\"" + itemname + "\"; filename=\"" + tempfilename + "\"" + lineEnd);
dataoutputstream.writeBytes("Content-Type: text/plain" + lineEnd + lineEnd);
// dataXML is File data, writes a string as the file content of the uploading
// file
dataoutputstream.writeBytes(dataXML);
dataoutputstream.writeBytes(lineEnd);
dataoutputstream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd); dataoutputstream.flush();
dataoutputstream.close();

String inputLine;
StringBuffer sbResponseData = new StringBuffer();
// Get the response data for the previous HTTP request
DataInputStream dis = new DataInputStream(connection.getInputStream());

while ((inputLine = dis.readLine()) != null) {
sbResponseData.append(inputLine + "\n");
}

dis.close();

return sbResponseData.toString();
}
catch (Exception ex) {
logger.error("Exception in initiating outdial call request: Details: " + ex.toString());

}

}

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