File Upload in Servlet 3.0
I played around a bit with the new servlet-api 3.0 and tomcat7 and i really like it. it has some nice features like servlet declaration using annotations or the support for asynchornous requesthandling, but the feature that i really really love is the support for file upload.
To handle a file upload form like this
<html>
<body>
<form action="upload" enctype="multipart/form-data" method="post">
<input type="file" name="filename"/>
<input type="submit" value="submit"/>
</form>
</body>
</html>
is to mark the servlet with an annotation and access the uploaded file using 'request.getPart("filename")' like this
package at.hpc.servlettest;
import java.io.*;
import javax.servlet.*;
import javax.servlet.annotation.*;
import javax.servlet.http.*;
@WebServlet(name="testUpload", urlPatterns={"/upload"})
@MultipartConfig
public class TestUpload extends HttpServlet {
protected void doPost( HttpServletRequest req, HttpServletResponse res )
throws ServletException, IOException {
Part part = req.getPart("filename");
res.setContentType( part.getContentType());
res.setHeader( "disposition", "inline" );
OutputStream out = res.getOutputStream();
InputStream in = part.getInputStream();
byte buffer[] = new byte[ 4048 ];
int n = 0;
while ((n = in.read( buffer )) > 0) {
out.write( buffer, 0, n );
}
out.close();
}
}
This is a really silly example that just copies the uploaded file back to the browser, but it shows how clean and simple handling fileuploads gets with this api - this is the feature i have been waiting for years!
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