Jakarta Commons Cookbook

11.9. Uploading Files with a Multipart POST

Problem

You need to upload a file or a set of files with an HTTP multipart POST.

Solution

Create a MultipartPostMethod and add File objects as parameters using addParameter( ) and addPart( ). The MultipartPostMethod creates a request with a Content-Type header of multipart/form-data, and each part is separated by a boundary. The following example sends two files in an HTTP multipart POST:

               import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.methods.MultipartPostMethod;
import org.apache.commons.httpclient.methods.multipart.FilePart;

HttpClient client = new HttpClient( );
        
// Create POST method
String weblintURL = "http://ats.nist.gov/cgi-bin/cgi.tcl/echo.cgi";
MultipartPostMethod method = 
    new MultipartPostMethod( weblintURL );

File file = new File( "data", "test.txt" );
               File file2 = new File( "data", "sample.txt" );
               method.addParameter("test.txt", file );
               method.addPart( new FilePart( "sample.txt", file2, "text/plain", "ISO-8859-1" ) ); 

// Execute and print response
client.executeMethod( method );
String response = method.getResponseBodyAsString( );
System.out.println( response );

method.releaseConnection( );

Two File objects are added to the MultipartPostMethod using two different methods. The first method, addParameter( ), adds a File object and sets the file name to test.txt. The second method, addPart(), adds a FilePart object to the MultipartPostMethod ...