Summary of three methods of Servlet implementing file upload
1. Get the uploaded file through getInputStream().
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/**
*
* @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 {
("text/html;charset=UTF-8");
//Read Request Body byte[] body = readBody(request);
//Get the string representation of all Body content String textBody = new String(body, "ISO-8859-1");
//Get the uploaded file name String fileName = getFileName(textBody);
//Get the file start and end positions Position p = getFilePosition(request, textBody);
//Output to file writeTo(fileName, body, p);
}
//Construction class class Position {
int begin;
int end;
public Position(int begin, int end) {
= begin;
= end;
}
}
private byte[] readBody(HttpServletRequest request) throws IOException {
//Get request text byte length int formDataLength = ();
//Get ServletInputStream input stream object DataInputStream dataStream = new DataInputStream(());
byte body[] = new byte[formDataLength];
int totalBytes = 0;
while (totalBytes < formDataLength) {
int bytes = (body, totalBytes, formDataLength);
totalBytes += bytes;
}
return body;
}
private Position getFilePosition(HttpServletRequest request, String textBody) throws IOException {
// Obtain file section boundary information String contentType = ();
String boundaryText = (("=") + 1, ());
//Get the actual momentum and end position of the file transmission int pos = ("filename=\"");
pos = ("\n", pos) + 1;
pos = ("\n", pos) + 1;
pos = ("\n", pos) + 1;
int boundaryLoc = (boundaryText, pos) - 4;
int begin = (((0, pos)).getBytes("ISO-8859-1")).length;
int end = (((0, boundaryLoc)).getBytes("ISO-8859-1")).length;
return new Position(begin, end);
}
private String getFileName(String requestBody) {
String fileName = (("filename=\"") + 10);
fileName = (0, ("\n"));
fileName = (("\n") + 1, ("\""));
return fileName;
}
private void writeTo(String fileName, byte[] body, Position p) throws IOException {
FileOutputStream fileOutputStream = new FileOutputStream("e:/workspace/" + fileName);
(body, , ( - ));
();
();
}
// <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 uploaded files through getPart() and getParts().
Body format:
POST HTTP/1.1
Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryrGKCBY7qhFd3TrwA
------WebKitFormBoundaryrGKCBY7qhFd3TrwA
Content-Disposition: form-data; name="text"
title
------WebKitFormBoundaryrGKCBY7qhFd3TrwA
Content-Disposition: form-data; name="file"; filename=""
Content-Type: image/png
PNG ... content of ...
------WebKitFormBoundaryrGKCBY7qhFd3TrwA--
[html] view plain copy
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package ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
/**
*
* @author Barudisshu
*/
@MultipartConfig
@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 {
Part part = ("photo");
String fileName = getFileName(part);
writeTo(fileName, part);
}
//Get uploaded file name private String getFileName(Part part) {
String header = ("Content-Disposition");
String fileName = (("filename=\"") + 10, ("\""));
return fileName;
}
//Storage files private void writeTo(String fileName, Part part) throws IOException, FileNotFoundException {
InputStream in = ();
OutputStream out = new FileOutputStream("e:/workspace/" + fileName);
byte[] buffer = new byte[1024];
int length = -1;
while ((length = (buffer)) != -1) {
(buffer, 0, length);
}
();
();
}
// <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 simpler method: use part wire (String fileName) to upload, and the browser will generate a temporary TMP file.
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* and open the template in the editor.
*/
package ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
/**
*Upload with part of the wire (String fileName), 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 Chinese file names ("UTF-8");
Part part = ("photo");
String fileName = getFileName(part);
//Write the file to the directory specified by location (fileName);
}
private String getFileName(Part part) {
String header = ("Content-Disposition");
String fileName = (("filename=\"") + 10, ("\""));
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 of this website to communicate and discuss. Thank you for reading. I hope it can help you. Thank you for your support for this website!