Servlet provides three methods for uploading files.

Servlet provides three methods for uploading files.

Summary of three methods for uploading files using Servlet

1. Get the uploaded file through getInputStream.

/*** To change this template, choose Tools | Templates * and open the template in the editor. */package net. individuals. web. servlet; import java. io. dataInputStream; import java. io. fileOutputStream; import java. io. IOException; import javax. servlet. servletException; import javax. servlet. annotation. webServlet; import javax. servlet. http. httpServlet; import javax. servlet. http. httpServletRequest; import javax. servlet. http. httpServletResponse;/***** @ author Barudisshu */@ WebServlet (name = "UploadServlet", urlPatterns = {"/UploadServlet "}) public class UploadServlet extends HttpServlet {/*** Processes requests for both HTTP * <code> GET </code> and * <code> POST </code> methods. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */protected void processRequest (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {response. setContentType ("text/html; charset = UTF-8"); // read the request Body byte [] body = readBody (request ); // get the String of all Body content to indicate String textBody = new String (body, "ISO-8859-1"); // get the name of the uploaded file String fileName = getFileName (textBody ); // get the start and end positions of the file. Position p = getFilePosition (request, textBody); // output to the file writeTo (fileName, body, p );} // construct class Position {int begin; int end; public Position (int begin, int end) {this. begin = begin; this. end = end ;}} private byte [] readBody (HttpServletRequest request) throws IOException {// get the request text byte length int formDataLength = request. getContentLength (); // get the ServletInputStream input stream object DataInputStream dataStream = new DataInputStream (request. getInputStream (); byte body [] = new byte [formDataLength]; int totalBytes = 0; while (totalBytes <formDataLength) {int bytes = dataStream. read (body, totalBytes, formDataLength); totalBytes + = bytes;} return body;} private Position getFilePosition (HttpServletRequest request, String textBody) throws IOException {// get the object segment Boundary Information String contentType = request. getContentType (); String boundaryText = contentType. substring (contentType. lastIndexOf ("=") + 1, contentType. length (); // obtain the momentum of the actually uploaded file and the ending position int pos = textBody. indexOf ("filename = \" "); pos = textBody. indexOf ("\ n", pos) + 1; pos = textBody. indexOf ("\ n", pos) + 1; pos = textBody. indexOf ("\ n", pos) + 1; int boundaryLoc = textBody. indexOf (boundaryText, pos)-4; int begin = (textBody. substring (0, pos )). getBytes ("ISO-8859-1 ")). length; int end = (textBody. substring (0, boundaryLoc )). getBytes ("ISO-8859-1 ")). length; return new Position (begin, end);} private String getFileName (String requestBody) {String fileName = requestBody. substring (requestBody. indexOf ("filename = \" ") + 10); fileName = fileName. substring (0, fileName. indexOf ("\ n"); fileName = fileName. substring (fileName. indexOf ("\ n") + 1, fileName. indexOf ("\" "); return fileName;} private void writeTo (String fileName, byte [] body, Position p) throws IOException {FileOutputStream fileOutputStream = new FileOutputStream (" e: /workspace/"+ fileName); fileOutputStream. write (body, p. begin, (p. end-p. begin); fileOutputStream. flush (); fileOutputStream. close ();} // <editor-fold defaultstate = "collapsed" desc = "HttpServlet methods. click on the + sign on the left to edit the code. ">/*** Handles the HTTP * <code> GET </code> method. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */@ Override protected void doGet (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {processRequest (request, response);}/*** Handles the HTTP * <code> POST </code> method. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */@ Override protected void doPost (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {processRequest (request, response);}/*** Returns a short description of the servlet. ** @ return a String containing servlet description */@ Override public String getServletInfo () {return "Short description";} // </editor-fold>}

2. Get the uploaded file through getPart () and getParts.

Body format:

POST http://www.example.com HTTP/1.1 Content-Type: multipart/form-data; boundary = ---- reply ------ response Content-Disposition: form-data; name = "text" title ------ WebKitFormBoundaryrGKCBY7qhFd3TrwA Content-Disposition: form-data; name = "file"; filename = "chrome.png" Content-Type: image/png PNG... content of chrome.png... ------ WebKitFormBoundaryrGKCBY7qhFd3TrwA -- [html] vie W plain copy/*** To change this template, choose Tools | Templates * and open the template in the editor. */package net. individuals. web. servlet; import java. io. fileNotFoundException; import java. io. fileOutputStream; import java. io. IOException; import java. io. inputStream; import java. io. outputStream; import javax. servlet. servletException; import javax. servlet. annotation. multipartConfig; import ja Vax. servlet. annotation. webServlet; import javax. servlet. http. httpServlet; import javax. servlet. http. httpServletRequest; import javax. servlet. http. httpServletResponse; import javax. servlet. http. part;/***** @ author Barudisshu */@ MultipartConfig @ WebServlet (name = "UploadServlet", urlPatterns = {"/UploadServlet "}) public class UploadServlet extends HttpServlet {/*** Processes requests for both H TTP * <code> GET </code> and * <code> POST </code> methods. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */protected void processRequest (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {Part part = request. getPart ("photo "); String fileName = getFileName (part); writeTo (fileName, part);} // get the Upload File Name private String getFileName (Part part) {String header = part. getHeader ("Content-Disposition"); String fileName = header. substring (header. indexOf ("filename = \" ") + 10, header. lastIndexOf ("\" "); return fileName;} // storage file private void writeTo (String fileName, Part part) throws IOException, FileNotFoundException {InputStream I N = part. getInputStream (); OutputStream out = new FileOutputStream ("e:/workspace/" + fileName); byte [] buffer = new byte [1024]; int length =-1; while (length = in. read (buffer ))! =-1) {out. write (buffer, 0, length);} in. close (); out. close ();} // <editor-fold defaultstate = "collapsed" desc = "HttpServlet methods. click on the + sign on the left to edit the code. ">/*** Handles the HTTP * <code> GET </code> method. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */@ Override protected void doGet (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {processRequest (request, response);}/*** Handles the HTTP * <code> POST </code> method. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */@ Override protected void doPost (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {processRequest (request, response);}/*** Returns a short description of the servlet. ** @ return a String containing servlet description */@ Override public String getServletInfo () {return "Short description ";}}

3. Another simple method: Use the wirte (String fileName) of the part to upload, And the browser will generate a temporary TMP File

/*** To change this template, choose Tools | Templates * and open the template in the editor. */package net. individuals. web. servlet; import java. io. IOException; import java. io. printWriter; import javax. servlet. servletException; import javax. servlet. annotation. multipartConfig; import javax. servlet. annotation. webServlet; import javax. servlet. http. httpServlet; import javax. servlet. http. httpServletRe Quest; import javax. servlet. http. httpServletResponse; import javax. servlet. http. part;/*** upload using the wirte (String fileName) of the part. The browser will generate a temporary TMP file. * @ Author Barudisshu */@ MultipartConfig (location = "e:/workspace") @ WebServlet (name = "UploadServlet", urlPatterns = {"/UploadServlet "}) public class UploadServlet extends HttpServlet {/*** Processes requests for both HTTP * <code> GET </code> and * <code> POST </code> methods. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */protected void processRequest (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {// process the request for a Chinese file name. setCharacterEncoding ("UTF-8"); Part part = request. getPart ("photo"); String fileName = getFileName (part); // write the file to the part in the directory specified by location. write (fileName);} private String getFileName (Part part) {String header = part. getHeader ("Content-Disposition"); String fileName = header. substring (header. indexOf ("filename = \" ") + 10, header. lastIndexOf ("\" "); return fileName;} // <editor-fold defaultstate =" collapsed "desc =" HttpServlet methods. click on the + sign on the left to edit the code. ">/*** Handles the HTTP * <code> GET </code> method. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */@ Override protected void doGet (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {processRequest (request, response);}/*** Handles the HTTP * <code> POST </code> method. ** @ param request servlet request * @ param response servlet response * @ throws ServletException if a servlet-specific error occurs * @ throws IOException if an I/O error occurs */@ Override protected void doPost (HttpServletRequest request, httpServletResponse response) throws ServletException, IOException {processRequest (request, response);}/*** Returns a short description of the servlet. ** @ return a String containing servlet description */@ Override public String getServletInfo () {return "Short description";} // </editor-fold>}

The above is an example of Servlet File Upload. If you have any questions, please leave a message or go to the community on this site for discussion. Thank you for reading this article and hope to help you. Thank you for your support for this site!