Java tutorial
/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ package controller; 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; public class UploadServlet extends HttpServlet { // 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 protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); try (PrintWriter out = response.getWriter()) { /* TODO output your page here. You may use following sample code. */ out.println("<!DOCTYPE html>"); out.println("<html>"); out.println("<head>"); out.println("<title>Servlet UploadServlet</title>"); out.println("</head>"); out.println("<body>"); out.println("<h1>Servlet UploadServlet at " + request.getContextPath() + "</h1>"); out.println("</body>"); out.println("</html>"); } } @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } @Override 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 { 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("msg", UPLOAD_DIRECTORY + "/" + fileName); request.setAttribute("message", "Upload has been done successfully >>" + UPLOAD_DIRECTORY + "/" + fileName); } } } } catch (Exception ex) { request.setAttribute("message", "There was an error: " + ex.getMessage()); } // redirects client to message page getServletContext().getRequestDispatcher("/message.jsp").forward(request, response); } }