Where to find a good working example on using Commons FileUpload library with JSP pages?

If you are looking a good working example on Commons FileUpload library with JSP pages, you can read the Apache Commons FileUpload Example with Servlet and JSP Web page.

Here is the Java source code of the Servlet that uses the Commons FileUpload API:

package net.codejava.upload;
 
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
 
/**
 * A Java servlet that handles file upload from client.
 *
 * @author www.codejava.net
 */
public class FileUploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
     
    // location to store file uploaded
    private static final String UPLOAD_DIRECTORY = "upload";
 
    // upload settings
    private static final int MEMORY_THRESHOLD   = 1024 * 1024 * 3;  // 3MB
    private static final int MAX_FILE_SIZE      = 1024 * 1024 * 40; // 40MB
    private static final int MAX_REQUEST_SIZE   = 1024 * 1024 * 50; // 50MB
 
    /**
     * Upon receiving file upload submission, parses the request to read
     * upload data and saves the file on disk.
     */
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // checks if the request actually contains upload file
        if (!ServletFileUpload.isMultipartContent(request)) {
            // if not, we stop here
            PrintWriter writer = response.getWriter();
            writer.println("Error: Form must has enctype=multipart/form-data.");
            writer.flush();
            return;
        }
 
        // configures upload settings
        DiskFileItemFactory factory = new DiskFileItemFactory();
        // sets memory threshold - beyond which files are stored in disk
        factory.setSizeThreshold(MEMORY_THRESHOLD);
        // sets temporary location to store files
        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
 
        ServletFileUpload upload = new ServletFileUpload(factory);
         
        // sets maximum size of upload file
        upload.setFileSizeMax(MAX_FILE_SIZE);
         
        // sets maximum size of request (include file + form data)
        upload.setSizeMax(MAX_REQUEST_SIZE);
 
        // constructs the directory path to store upload file
        // this path is relative to application's directory
        String uploadPath = getServletContext().getRealPath("")
                + File.separator + UPLOAD_DIRECTORY;
         
        // creates the directory if it does not exist
        File uploadDir = new File(uploadPath);
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }
 
        try {
            // parses the request's content to extract file data
            @SuppressWarnings("unchecked")
            List<FileItem> formItems = upload.parseRequest(request);
 
            if (formItems != null && formItems.size() > 0) {
                // iterates over form's fields
                for (FileItem item : formItems) {
                    // processes only fields that are not form fields
                    if (!item.isFormField()) {
                        String fileName = new File(item.getName()).getName();
                        String filePath = uploadPath + File.separator + fileName;
                        File storeFile = new File(filePath);
 
                        // saves the file on disk
                        item.write(storeFile);
                        request.setAttribute("message",
                            "Upload has been done successfully!");
                    }
                }
            }
        } catch (Exception ex) {
            request.setAttribute("message",
                    "There was an error: " + ex.getMessage());
        }
        // redirects client to message page
        getServletContext().getRequestDispatcher("/message.jsp").forward(
                request, response);
    }
}

 

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